LionChief Curcuit Board with 4 Ohm load?

You don't want to go lower than the stock 8 ohm impedance.  It may work for a spell, but you're overloading the audio amp.  Use two 16 ohm speakers in parallel if you want to add a speaker.

Thanks John

John

I do wonder how much louder, replacing the original 8 Ohm speaker with 2x 16 Ohm speakers would be...  My guess is little difference.

More gain could be achieved by connecting a small, maybe 5 Watt Amp to the stock amp's output.  If doing this, a speaker with more power handling capability and impedance matched to the second amp's output may also be necessary.  The other consideration is that a T-pad or similar resistor configuration may need to be added in between the two amps for sufficient output loading and/or input level matching.

@SteveH posted:

I do wonder how much louder, replacing the original 8 Ohm speaker with 2x 16 Ohm speakers would be...  My guess is little difference.

With the second speaker emitting sound out the top of the coal load it would be quite significant

More gain could be achieved by connecting a small, maybe 5 Watt Amp to the stock amp's output.  If doing this, a speaker with more power handling capability and impedance matched to the second amp's output may also be necessary.  The other consideration is that a T-pad or similar resistor configuration may need to be added in between the two amps for sufficient output loading and/or input level matching.

That sounds really interesting Steve

John

Whether the sound would be louder with 2 speakers depends on a few of things.

With 2x 16 Ohm speakers connected to an amplifier wanting to see an 8 Ohm load, the power consumed by each speaker will be about half as much as a single 8 Ohm speaker, thus each speaker will be putting out about half as much sound volume.

However, generally speaking, 16 Ohm speakers are typically slightly more efficient than 8 Ohm speakers, but usually only by a few percent.

With FasTrack and other rigid/highly acoustically reflective track systems and roadbeds, most of the sound coming out of the bottom of a tender is reflected back outwards towards the listener, though slightly out of phase, depending upon the frequency.  Having two speakers will increase the acoustic phase distortions.   Meaning, some audio frequencies will seem louder and others quieter.

So that's why I think two 16 Ohm speakers may not be much louder than one, if at all.  The only way to know for sure if two speakers will be loud enough is to try it.

Adding more amplification and a more powerful speaker, IMO is more likely to produce the desired result, but would be more work.

How about two four ohm speakers in series?

John

Same phase distortion issues.  Also 4 Ohm speakers are usually less efficient than 8 Ohm speakers.

@SteveH posted:

Also 4 Ohm speakers are usually less efficient than 8 Ohm speakers.

I have no idea how efficient the stock 8 ohm speaker even is.  Maybe that's the problem.  The Santa Fe Super Chief RTR set is much louder all the way around for example.

John

Replacing the stock speaker with one that's more efficient would make the sound from the tender somewhat louder.  However, finding out the efficiency of the stock speaker for comparison may prove difficult, unless you have the required measurement equipment.  Efficiency or Sensitivity ratings are given in decibels.  Here's a link to a basic description of Speaker Efficiency and Sensitivity and how to measure it.

Some people swear by Fat Boy speakers...  I haven't personally tried one as a direct replacement for a stock speaker and am unsure how efficient they may be.  Also I'm unsure if the magnet would fit in the space available inside that tender.  If interested, perhaps you can find the efficiency rating and dimensions of one in the correct driver size in some online documentation.

Someone on another forum who was trying to reverse engineer the circuit said that both Lionchief and LC+ use the same 1W cheap amp CE0030B. Here is the data sheet.

On his own LC engines he uses these 4 Ohm speakers to increase volume, but he said that you have to be careful about the sound files pared with it because a loud chuff (for example) could wreck the amp.

John

John, if there is room in the tender for it, I would still advise adding a resistor pad (between the amps), secondary 5Watt booster amp, and speaker that will handle the additional wattage.  I estimate the total parts cost would be about $30 - $40.

If you swap in a 4 Ohm speaker and blow the IC chip amp on the LC board, replacing the entire board would run you about $75 plus shipping.  If you have the skills to replace just the chip, and you can find an exact replacement, then just swapping to a 4 Ohm speaker may be an acceptable risk.

@Craftech posted:

On his own LC engines he uses these 4 Ohm speakers to increase volume, but he said that you have to be careful about the sound files pared with it because a loud chuff (for example) could wreck the amp.

Like I said, limit the impedance to 8 ohms or more.

@SteveH posted:

John, if there is room in the tender for it, I would still advise adding a resistor pad (between the amps), secondary 5Watt booster amp, and speaker that will handle the additional wattage.  I estimate the total parts cost would be about $30 - $40.

Steve, doing two speakers, even impedance matching, can significantly increase the volume.  One only has to look at some of the higher end Lionel steamers with two 16 ohm speakers instead of one 8 ohm speaker and hear the difference to realize this is quite possibly a major improvement in sound.

While I'm sure adding the amp will increase the volume, it's also a bit of a PITA, adding the speaker is much easier.

Another very effective method is to add a proper baffle to the speaker, that can greatly increase the volume, and also increase the bass in the sounds.

John, I have no doubt that the higher end stock steamers with two matched speakers have better sound.  These two speakers are in a purpose designed enclosure, mounted close to each other on the same physical plane and are both firing in the same direction.  This reduces the acoustic phase distortion and the two drivers effectively couple with each other to improve the overall bass response.  They also likely have a more powerful amp driving them than the CE0030B.  So yes, I agree that will sound louder and better.

Craftech John has already installed a baffle with little improvement.

@Craftech posted:

LionChief 0-8-0 too quiet, barely audible especially with 2nd loco especially on FasTrack.

Tender barely has enough headroom for a baffle.  I made one anyway and drilled a few extra speaker holes in the bottom because Lionel mounted the speaker off center from the grill holes.

Barely a difference in volume.

I still remain very skeptical that adding a second speaker to this tender (keeping the same total load impedance on the amp) will make a significant improvement, unless the two replacement 16 Ohm speakers are markedly more efficient than the stock 8 Ohm speaker.

When 2 speakers reproducing an identical sound source are not physically aligned with each other and at an optimal distance apart, the combined sound from them results in a type of acoustic phase distortion referred to as Comb Filtering.  The net result is that some frequencies are perceived to be louder and others quieter.  The overall perceived difference can be very subjective, depending on the person and their location relative to the sound source.

I guess I could open up the LionChief Santa Fe to see what's different about it when I get a chance.  That sounds great with a single speaker.

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Also, I looked awhile ago for any posts that explained how to disassemble a Lion Chief 0-8-0 and couldn't find one.  Have any of you seen that?

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Steve,

How are you suggesting the add-on amp be powered?

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When I did the Bachmann HO K4 with a TCS WOW sound decoder it was an older model which was not sound ready (barely decoder ready) so no downward firing speaker section molded onto the bottom of the tender.  So what I did was to drill a lot of tiny holes in the top of the coal load of the tender and seal the edges of the entire tender.  I mounted the speaker at the opposite end (It came with a tight fitting baffle) turning the entire tender chamber into a resonator that let the sound out the top.  The sound is dramatic for a small tender.

In terms of O Gauge and Fastrack I would think the speaker emitting sound a half inch from noisy Fastrack would cancel a lot of the volume.

John

@Craftech posted:

Steve, How are you suggesting the add-on amp be powered?

John

If there's a suitable DC power source on the LC board, a modified tether between the Locomotive would be required to run power back to the tender.  I don't know if a suitable DC source is there already.

Depending upon the available space for everything inside the tender, an appropriate AC to DC buck converter getting it's input power from Track power may be a better alternative.  This may require adding a pick-up roller and axle wiper if the tender doesn't already have them.  Exactly which buck converter would depend on the selected Amplifier's voltage and power requirements and space constraints.

What's the model number of your 0-8-0?

@SteveH posted:

If there's a suitable DC power source on the LC board, a modified tether between the Locomotive would be required to run power back to the tender.  I don't know if a suitable DC source is there already.

Depending upon the available space for everything inside the tender, an appropriate AC to DC buck converter getting it's input power from Track power may be a better alternative.  This may require adding a pick-up roller and axle wiper if the tender doesn't already have them.  Exactly which buck converter would depend on the selected Amplifier's voltage and power requirements and space constraints.

What's the model number of your 0-8-0?

http://www.lionel.com/products...w-bluetooth-1923040/

https://www.lionelsupport.com/...LOCO-ONLY-1923041001

The tender has both an axle wiper and a pickup roller.

Thanks Steve,

John

@gunrunnerjohn posted:

Like I said, limit the impedance to 8 ohms or more.

Steve, doing two speakers, even impedance matching, can significantly increase the volume.  One only has to look at some of the higher end Lionel steamers with two 16 ohm speakers instead of one 8 ohm speaker and hear the difference to realize this is quite possibly a major improvement in sound.

A major mismatch in the power handling capability could impact the performance.

@gunrunnerjohn posted:

A major mismatch in the power handling capability could impact the performance.

I haven't really searched so maybe assuming low power handling for 28mm speakers is getting ahead of myself.

Thanks John,

John

I don't have any LionChief locos but I have not heard anyone complaining about lack of volume.  Have you tried to diagnose the problem with your stock sound system ?  Has the volume been too quiet since new ? I am assuming it has a pot under the tender are all three wires connected ? If it has been this way since new perhaps the problem is on the board.  On occasion I have fixed problem by reflowing soldering joints. I think some of the LionChief boards can be controlled with TMCC you might try accessing the sound with a TMCC controller. If the amp on the board is not putting out the designed wattage/volume adding speakers is not going to fix the problem.          j

Only Lionchief Plus 2.0 can be controlled using TMCC.

@JohnActon posted:

I don't have any LionChief locos but I have not heard anyone complaining about lack of volume.  Have you tried to diagnose the problem with your stock sound system ?  Has the volume been too quiet since new ? I am assuming it has a pot under the tender are all three wires connected ? If it has been this way since new perhaps the problem is on the board.  On occasion I have fixed problem by reflowing soldering joints. I think some of the LionChief boards can be controlled with TMCC you might try accessing the sound with a TMCC controller. If the amp on the board is not putting out the designed wattage/volume adding speakers is not going to fix the problem.          j

There is no pot under the tender.

Problem has been there since new and coincides with other comments on some forums. 

Not sure how to disassemble the engine.  Started to, but some parts were not obvious.  Never could find a post somewhere on the net on how to.  Oddly, I can disassemble a Bachmann and a Kato  N Gauge steamer which I think is probably more difficult.  Spookshow is a good source for that.

John

Maybe lower wattage speakers would be more efficient.  According to the data sheet for the CE0030B the amp puts out less than 1W.  28mm speakers appear to only be available around 0.25W anyway.

John

Here is a comparison between the LC 0-8-0 speaker and the LC Super Chief speaker (both from RTR sets).

Santa Fe LC speaker enclosed in a baffle under the chassis.  8 ohms 0.5W but smaller magnet.  Adequate clear volume.

0-8-0 LC speaker located above the chassis.  8 ohms 3W with much larger magnet inside my homemade baffle made from a pill bottle.  Muted volume even with addition of a baffle.

John

Right now I have an AC to DC buck converter that seems pretty good.  DC output is adjustable.

The problem are the two DC amp modules I bought.  One is mono and one is stereo.

The mono board (ASAIK) only puts out 1W.  It has a purported gain of 200X.   The stereo board puts out 3W + 3W.  I don't think the stereo board is bridgeable (not sure) so I would have to use only one side of it.

Is it even safe to use the speaker output in the LC tender as an amp module input?  Aren't those little amps looking for line level outputs at their inputs and won't a whole lot of distortion occur if I do that?

And what (if any) damage to the Lionel audio board might occur?

Thanks,

John

@Craftech posted:

Is it even safe to use the speaker output in the LC tender as an amp module input?  Aren't those little amps looking for line level outputs at their inputs and won't a whole lot of distortion occur if I do that?

@SteveH posted:

...

More gain could be achieved by connecting a small, maybe 5 Watt Amp to the stock amp's output.  If doing this, a speaker with more power handling capability and impedance matched to the second amp's output may also be necessary.  The other consideration is that a T-pad or similar resistor configuration may need to be added in between the two amps for sufficient output loading and/or input level matching.

@Craftech posted:

And what (if any) damage to the Lionel audio board might occur?

If the T-pad is designed correctly, the output level of the Lionel amp would be attenuated sufficiently (to feed a line level into the secondary amp) while simultaneously loading the first amp to around 8 Ohms.  Here's a link to further reading about T-pads

So if the individual resistor values in the T-Pad are chosen appropriately, then there shouldn't be any damage to any of the components.  Distortion can also be minimized to be in line with the amps' nominal specifications with appropriate T-pad design.

@SteveH posted:

If the T-pad is designed correctly, the output level of the Lionel amp would be attenuated sufficiently (to feed a line level into the secondary amp) while simultaneously loading the first amp to around 8 Ohms.  Here's a link to further reading about T-pads

So if the individual resistor values in the T-Pad are chosen appropriately, then there shouldn't be any damage to any of the components.  Distortion can also be minimized to be in line with the amp's nominal values with appropriate T-pad design.

I remember you mentioning the T-Pad earlier Steve.  I just wonder if the 1W mono amp would even work.  Don't I need more wattage?

John

It’s difficult to say whether the 1 Watt amp would be as loud as you want.  If you were to use the 3 Watt stereo amp, one of its channels could be used with a single 3W or higher rated speaker.  The other channel would be idle.  Unless the stereo amp is designed for its outputs to be bridged, I suggest not trying that lest the magic smoke may appear.

@SteveH posted:

It’s difficult to say whether the 1 Watt amp would be as loud as you want.  If you were to use the 3 Watt stereo amp, one of its channels could be used with a single 3W or higher rated speaker.  The other channel would be idle.  Unless the stereo amp is designed for its outputs to be bridged, I suggest not trying that lest the magic smoke may appear.

I may try it anyway as long as the magic smoke only occurs in the cheap 3W amp and not the Lionel amp board.

Also, there are T-Pad calculators which first ask how many dB reduction are being sought.   That'll be guesswork at best.

https://www.allaboutcircuits.c...tenuator-calculator/

John

Without access to detailed specifications on the amps, using essentially a trial and error approach, I’d suggest starting with about 50dB of gain reduction.  It’ll probably end up much less maybe in the 20 to 30 range.

Looking at the example schematic in the wiki link referenced above, I’d start with a Logarithmic taper variable resistor in the R3 position that would yield around 50dB max attenuation and then dial in the desired volume.

@Craftech posted:

LionChief 0-8-0 too quiet, barely audible especially with 2nd loco especially on FasTrack.

Tender barely has enough headroom for a baffle.  I made one anyway and drilled a few extra speaker holes in the bottom because Lionel mounted the speaker off center from the grill holes.

Barely a difference in volume.

I have a 30mm 8 ohm speaker which I could mount up inside of the coal load facing upward.  Small holes drilled in the black coal load are not noticeable.  I have confirmed this with an HO installation I did a few months ago.   I want to hook this up in parallel to the existing 8 ohm speaker.

What I don't know is if the resulting 4 ohm load will damage the LionChief circuit board.

Anyone know?

Thanks,

John

I don't know if this would work in your case but in the American Flyer Flyerchief engines I have I pulled the stock speaker and replaced it with the Fatboy speaker included with the sound boards that ERR sold, that made a vast improvement.

Ray

Dumb question, but have you tried the volume control? With the engine stopped, blow the whistle and at the same time turn the throttle up.

@Rayin"S" posted:

I don't know if this would work in your case but in the American Flyer Flyerchief engines I have I pulled the stock speaker and replaced it with the Fatboy speaker included with the sound boards that ERR sold, that made a vast improvement.

Ray

I have several speakers both square and round, but the height is a limitation as anything more than 25mm will hit the coal load area or at least one of it's retaining screws.  So I am experimenting.

Thanks,

John

@Chuck Sartor posted:

Dumb question, but have you tried the volume control? With the engine stopped, blow the whistle and at the same time turn the throttle up.

Yes.  Thanks Chuck.  On mine, it is actually Hold down announcement button and turn throttle up.  Varies.

John

Chuck that’s a great question.  I had assumed (yes I know) that John was aware of this feature based on previous conversations.  

The manual for this locomotive says this:

“Adjusting the locomotive volume with the Universal Remote

To adjust the overall volume of the locomotive's sound system begin by placing the throttle 1 in the top dead center position (so the red LED is solidly illuminated and the locomotive is stopped). Press and hold the Announcement button then turn the throttle to the left and / or right, this will increase and decrease the overall locomotive volume. Continue holding the Announcement button when turning the throttle, you can stay in this mode until the volume is at the level you desire. Once the volume level is set to the level you want release the Announcement button and return the locomotive throttle to the top dead center position again. (The new volume level will remain until you change it in the future, even after power has been cycled.) If, after running the locomotive, you decide to change the volume, simply follow the steps above to do so.

Note!

If the throttle is not in the top dead center position before or after the volume adjustment process undesired operation will occur. Always start and finish the volume adjustment process with the throttle in the top dead center position!”

@SteveH posted:

Without access to detailed specifications on the amps, using essentially a trial and error approach, I’d suggest starting with about 50dB of gain reduction.  It’ll probably end up much less maybe in the 20 to 30 range.

Looking at the example schematic in the wiki link referenced above, I’d start with a Logarithmic taper variable resistor in the R3 position that would yield around 50dB max attenuation and then dial in the desired volume.

Also, some of those amp boards claim those max wattage ratings with a 2 ohm load !!. The "stereo" ones are often NOT two channel.  Both left and right are identical and are probably a split.  There is a 5W / 5W board that puts out 3W at 4 ohms and a 3W / 3W that puts out 3W at 4 ohms.

You said it Steve.  Trial and error.

Thanks,

John

John send me a link to the 3 + 3 Watt amp and I’ll look at it’s specs.  May have some useful info for choosing resistor values.

@SteveH posted:

John send me a link to the 3 + 3 Watt amp and I’ll look at it’s specs.  May have some useful info for choosing resistor values.

Thanks Steve.  Much appreciated:

https://www.amazon.com/dp/B01D...dt_b_product_details

John

Here's a link to the datasheet for the amplifier chip that this module uses: PAM8403

Not much info on the board mfg.'s site HiLetGo PAM8403 Super Mini 5V 3W*2 Digital Amplifier Board USB Powered Volume Control

Maybe I missed it, but I'm not seeing it's input impedance.

1. To get a better idea of what we're dealing with, could you measure the resistance across it's input connections with the volume control potentiometer fully clockwise and again with the pot fully CCW?
2. Do you have an assortment of 1/2 or 1 Watt resistors in the 1 to10 Ohm range?
3. How about an assortment of 1/4 Watt resistors in between 100 and 1kOhms?
4. What values of potentiometers would you have on hand?

Feel free to PM me with answers to 2, 3, and 4.

@SteveH posted:

Here's a link to the datasheet for the amplifier chip that this module uses: PAM8403

Not much info on the board mfg.'s site HiLetGo PAM8403 Super Mini 5V 3W*2 Digital Amplifier Board USB Powered Volume Control

Maybe I missed it, but I'm not seeing it's input impedance.  

---------------------------------------------------------------

THEY DON'T STATE IT

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1. To get a better idea of what we're dealing with, could you measure the resistance across it's input connections with the volume control potentiometer fully clockwise and again with the pot fully CCW?      THE POT VARIES THE OUTPUT NOT THE INPUT
2. Do you have an assortment of 1/2 or 1 Watt resistors in the 1 to10 Ohm range?  YES
3. How about an assortment of 1/4 Watt resistors in between 100 and 1kOhms?  YES
4. What values of potentiometers would you have on hand?  I HAVE A LOT OF DUAL TAPER 10K AUDIO POTS FROM ALTOID TIN HEADPHONE AMP PROJECTS I USED TO DO.  ALSO SOME 10K TRIM POTS

Feel free to PM me with answers to 2, 3, and 4.

John

Good to know.  So what's the measured input resistance?  I'm guessing around 10kΩ, but it would be good to measure it and also make sure that the pot doesn't affect this reading.

@SteveH posted:

Good to know.  So what's the measured input resistance?  I'm guessing around 10kΩ, but it would be good to measure it and also make sure that the pot doesn't affect this reading.

No reading even at the R x 1 scale regardless of pot position.

John

It makes sense you wouldn't see a reading at the lowest scale.  What the highest resistance scale you tried?

For the heck of it I put a 4 ohm wirewound resistor in series with a 4 ohm speaker.   As I suspected the volume was even lower.

John

@SteveH posted:

It makes sense you wouldn't see a reading at the lowest scale.  What the highest resistance scale you tried?

Yes, of course.  Around 40kΩ Steve.  Regardless of pot position

You have an Ohms symbol on your keyboard?

John

Catch 22- trying to measure an amplifier input impedance (AKA complex resistance) using a multimeter. Why? The meter supplies DC, and many amplifiers specifically use isolating capacitors that block DC. You need a frequency generator and sweep the input across an audible frequency range and THEN you might get a result.

The tip is the name impedance- not resistance. Impedance is used implying a complex state (range of frequencies) VS DC steady state- what most meters are only capable of.

@Vernon Barry posted:

Catch 22- trying to measure an amplifier input impedance (AKA complex resistance) using a multimeter. Why? The meter supplies DC, and many amplifiers specifically use isolating capacitors that block DC. You need a frequency generator and sweep the input across an audible frequency range and THEN you might get a result.

The tip is the name impedance- not resistance. Impedance is used implying a complex state (range of frequencies) VS DC steady state- what most meters are only capable of.

Vernon, of course you're right.  Impedance is a vector: either between resistance and capacitance or resistance and inductance.

However, in my experience, one can sometimes get an approximation (within 20-30%) of the impedance of an audio device's input by measuring resistance.  Usually they're in the vicinity of 150, 600, 1k, 2k, 10k and sometimes 40kΩ or higher.  John's measurement will give me a better idea where to start with experimental T-pad resistor value suggestions.

@Craftech posted:

Yes, of course.  Around 40K Steve.  Regardless of pot position

You have an Ohms symbol on your keyboard?

John

Omega and other special characters can be accessed on my computer, like so:

Not sure how to access these special characters on my phone though...

@SteveH posted:

Vernon, of course you're right.  Impedance is a vector: either between resistance and capacitance or resistance and inductance.

However, in my experience, one can sometimes get an approximation (within 20-30%) of the impedance of an audio device's input by measuring resistance.  Usually they're in the vicinity of 150, 600, 1k, 2k, 10k and sometimes 40kΩ or higher.  John's measurement will give me a better idea where to start with experimental T-pad resistor value suggestions.

Omega and other special characters can be accessed on my computer, like so:

Not sure how to access these special characters on my phone though...

Nice.  Thanks.  Never noticed it.

John

From a 1997 article by Tom Engdahl entitled Connecting speaker signals to line level imputs:

Suitable for 1W - 50W amps.  Signal attenuation 20dB

Adjustable output level

If you want to adjust the output level then replace R2 with 1 kohm trimmer. This makes it possible to make the output level to be adjustable from 0V to line level.

----------------------------------------------------------------------------------------------------------------------------------------

I may try it.

John

@Craftech posted:

From a 1997 article by Tom Engdahl entitled Connecting speaker signals to line level imputs:

Suitable for 1W - 50W amps.  Signal attenuation 20dB

Adjustable output level

If you want to adjust the output level then replace R2 with 1 kohm trimmer. This makes it possible to make the output level to be adjustable from 0V to line level.

----------------------------------------------------------------------------------------------------------------------------------------

I may try it.

John

John, I'd say go for it with the 1kOhm in the R2 position, starting at full attenuation and then slowly increase the voltage.  Maybe obvious, but just in case it's not, with the trimmer, the Line Out would be connected to the center tap on the potentiometer instead of between the resistors as shown in the original schematic.

@SteveH posted:

John, I'd say go for it with the 1kOhm in the R2 position, starting at full attenuation and then slowly increase the voltage.  Maybe obvious, but just in case it's not, with the trimmer, the Line Out would be connected to the center tap on the potentiometer instead of between the resistors as shown in the original schematic.

Thanks Steve,

I ordered a 1K trim pot (I only had a lot of 10K) so I used the fixed resistor.   The HiLetgo amp had the same volume output with two different 4Ω speakers as the original 8Ω stock setup.

Then I tried an LM386 board I had ordered and it fried.  Really low quality.  Those are going back.

Right now I am experimenting with a tiny Adafruit 2.5W Class D mini mono amp.   With the trimmer all the way up there was an increase in volume with one of the 4Ω speakers.  I haven't tried the other one yet.

I'll keep everyone posted.  The 1K trim pots will be here on Tuesday.

By the way, the AC - DC buck converter is fantastic.  You can dial in precise DC voltages from track power.

John

John,  Based on your experiments, it seems like the LC amp's output is already low enough that the R1{10kΩ} R2{1kΩ} L-pad is attenuating the signal too much.  If you still have the 3 + 3 W HiLetgo, you could easily devise a lesser L-pad attenuator with -3, -6, -12, and -18dB connection taps providing the output signal.

Since you already have a good resistor assortment and understanding of audio terminology, I'm going to recommend that you use something like the resistor ladder shown in Figure 2 within this Article Attenuators for Measurement by Jonathan Novic.  Note, that the 1Ohm resistor values shown in Figure 2 are representative and can be substituted (see Table 2) with other values such that each resistor in the ladder has the same value.

@SteveH posted:

John,  Based on your experiments, it seems like the LC amp's output is already low enough that the R1{10kΩ} R2{1kΩ} L-pad is attenuating the signal too much.  If you still have the 3 + 3 W HiLetgo, you could easily devise a lesser L-pad attenuator with -3, -6, -12, and -18dB connection taps providing the output signal.

Since you already have a good resistor assortment and understanding of audio terminology, I'm going to recommend that you use something like the resistor ladder shown in Figure 2 within this Article Attenuators for Measurement by Jonathan Novic.  Note, that the 1Ohm resistor values shown in Figure 2 are representative and can be substituted (see Table 2) with other values such that each resistor in the ladder has the same value.

Although the article was written to address the effects on high wattage amps the idea sounds good, but if I am attenuating the signal too much either a trimmer (which is arriving on Tuesday) or trial and error might be more practical than a ladder.

But see if this sounds right:

The Lionel amplifier circuit probably puts out 2W at 8Ω which is 4V.  That's around +14dBu which varies.  My guess is that the average level of announcements, chuff, horn, and bell is around +4dBu which is exactly LINE LEVEL.   So either no attenuation is necessary or very little to avoid possible distortion.

John

@Craftech posted:

Although the article was written to address the effects on high wattage amps...

Not just high watt amps, the L-Pad design principles discussed in the article apply to any amplifier circuit in the audible frequency range.

@Craftech posted:

...So either no attenuation is necessary or very little to avoid possible distortion.

John

I think this is likely, I'm now thinking somewhere between -3 and -9dB may be about right.

As far as testing with the ladder, I'd use one of these project breadboards or without that, a series of alligator clip leads.

Also note: the ladder doesn't have to necessarily have to be made with an individual resistor in each of the locations shown in the diagram.  For example, where two 1Ω are in series between taps, a 2Ω could be substituted.  There are several locations where substitutions could be made to yield essentially the same circuit for testing purposes.  When making substitutions, as long as the ratios between Rseries and Rshunt remain the same, the circuit attenuation is the same at each tap.

I have not seen suggested yet is Lionel's separate Amplifier board. PN# 8007-110 or 691-8018-T25. S&W Train parts lists the 8007-110 in stock.

@SteveH posted:

I think this is likely, I'm now thinking somewhere between -3 and -9dB may be about right.

Since the Lionel amplifier circuit's output is adjustable with the LC remote would that not act as a variable attenuator that can be left alone once the ideal output level is found?   Adjusting is cryptic enough that it is unlikely to be accidentally changed.

John

@Chuck Sartor posted:

I have not seen suggested yet is Lionel's separate Amplifier board. PN# 8007-110 or 691-8018-T25. S&W Train parts lists the 8007-110 in stock.

My concern with that is that the DC ground of the Lionchief amplifier is NOT the same as the separately powered and half wave rectified old school amp board. In fact, I'm thinking the problem exists even with these other amp boards and may have been why the LM386 popped.

The lionchief board rectifies ALL power coming in through a full wave bridge. Then in theory, the DC common (mistakenly called ground in some cases) would not be equal to frame ground. Older Lionel electronics often used half wave rectification, such that AC frame common was actually DC common too in those circuits.

This is a problem- that straight line assumes that the power source for the amplifier is at this same DC common potential.

@Chuck Sartor posted:

I have not seen suggested yet is Lionel's separate Amplifier board. PN# 8007-110 or 691-8018-T25. S&W Train parts lists the 8007-110 in stock.

Thanks Chuck.

The railsounds amp might be a good option as an auxiliary amp, but I think it is larger than the tiny ones I am working with.  I also have some stick on weights inside the tender and a DIY back-up light circuit.

John

@Vernon Barry posted:

My concern with that is that the DC ground of the Lionchief amplifier is NOT the same as the separately powered and half wave rectified old school amp board. In fact, I'm thinking the problem exists even with these other amp boards and may have been why the LM386 popped.

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There have been other complaints in the user reviews about quality issues with those particular boards.   So that can't be discounted.

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The lionchief board rectifies ALL power coming in through a full wave bridge. Then in theory, the DC common (mistakenly called ground in some cases) would not be equal to frame ground. Older Lionel electronics often used half wave rectification, such that AC frame common was actually DC common too in those circuits.

This is a problem- that straight line assumes that the power source for the amplifier is at this same DC common potential.

From Tom Engdahl's article from which the circuit diagram was taken:

Notes on using the circuit

Remember to check that the circuit is connected in the right way every time you use it. If you mix up speaker out and speaker ground connection, you can end up shorting speaker output to ground, which can damage your amplifier and/or other equipment connected to it. If you want to redice the risk of damaging anythign then put 10 ohm resistor between the circuit and speaker ground connector (this will make sure that short circuit impedance is always at least 10 ohms, though it can introduce sometime hummign problems because of increase grounding impendace).

John

@Craftech posted:

Since the Lionel amplifier circuit's output is adjustable with the LC remote would that not act as a variable attenuator that can be left alone once the ideal output level is found?   Adjusting is cryptic enough that it is unlikely to be accidentally changed.

John

That could work.  Although, I can see the possibility of an inadvertent press of the announcement button while simultaneously attempting to throttle up from stop.

Once you discover the right amount of attenuation, constructing a final design L-pad would only require two resistors.

@Chuck Sartor thanks for the tip about the Lionel's separate amp board [PN# 8007-110 or 691-8018-T25].  I did find it on the S&W Parts Site, but there's no detailed info about it there or on Lionel's parts site.  Do you happen to have any specs for it?

Sorry, no specs. Track power in, speaker input and then out to the speaker.

@SteveH posted:

That could work.  Although, I can see the possibility of an inadvertent press of the announcement button while simultaneously attempting to throttle up from stop.

Once you discover the right amount of attenuation, constructing a final design L-pad would only require two resistors.

@Chuck Sartor thanks for the tip about the Lionel's separate amp board [PN# 8007-110 or 691-8018-T25].  I did find it on the S&W Parts Site, but there's no detailed info about it there or on Lionel's parts site.  Do you happen to have any specs for it?

I seem to recall somewhere that it's output is 5W, but I don't know if that is into a 4Ω load or an 8Ω load.  EDIT:  That can't be right, sorry.  Here is the board in an American Flyer PB-1 dummy.

https://www.lionelsupport.com/...26-48117Complete.pdf

It is connected to a 600-8152-536 speaker.  I looked up that speaker.  It is 16 Ohms and it is only rated at 0.2W.

John

@Craftech posted:

From Tom Engdahl's article from which the circuit diagram was taken:

Notes on using the circuit

Remember to check that the circuit is connected in the right way every time you use it. If you mix up speaker out and speaker ground connection, you can end up shorting speaker output to ground, which can damage your amplifier and/or other equipment connected to it. If you want to redice the risk of damaging anythign then put 10 ohm resistor between the circuit and speaker ground connector (this will make sure that short circuit impedance is always at least 10 ohms, though it can introduce sometime hummign problems because of increase grounding impendace).

John

Unless you are also powering this external amplifier from the very DC rectified sources on the Lionchief board- there is a chance of the audio ground or common being mismatched potentials creating a ground loop situation.

Yes, one could work around this with a speaker to line level converter that provided electrical isolation (often using a transformer- but there are other methods) to again prevent ground loop on a single ended signal like line level input.

Again it would be shear luck, that the amplifier you are using externally, in theory with a bridge rectifier and regulator, that the DC common would be noise free and at the same potential as the Lionchief amp speaker negative output.

Vernon, thank you for your insights on these ground issues. I believe John is using a buck converter to power the secondary amp.

Regardless, it seems that a check for DC potential between the onboard LC amp Out (-) and the secondary amp In(-) would be in order.

Isn't the speaker in the 0-8-0 rated at 3 watts? I think Lionel's separate amp board would provide plenty of sound. But I'm not an electronics engineer.

@Chuck Sartor posted:

Isn't the speaker in the 0-8-0 rated at 3 watts? I think Lionel's separate amp board would provide plenty of sound. But I'm not an electronics engineer.

You would think, but alas - No.  Completely drowned out by track noise even at low speeds unlike Santa Fe Super Chief starter set diesel loco.  Dramatic difference.

John

Update:

Here's where I am with this experiment.

1.  Definitely louder sounds with either the HiLetgo or Adafruit mini amps with a 4Ω speaker (tried two different ones) powered by an AC/DC Buck converter.   Seems to work the best without any attenuation on the Lionel amplifier speaker outputs.  Input level can be controlled with the Lionel remote.  Both mini amps also have trim pots.

The problem with it is that there is an interruption in the sound when it goes across the insulated sections of the FasTrack switches (see below)

Those are necessary to prevent shorts with certain wheels (Example:  Lionel Santa Fe Super Chief RTR set).

The only way to combat the interruptions would be for me to install a second pickup on the other truck which I really don't want to do.  Maybe someone else someday may want to try that.  Frankly I have had it with messing with mini amps inside this thing.

I removed all of it.

2.  So then, despite the warnings about overloading the Lionel amp I tried two different 4Ω 3W speakers in place of the stock 8Ω speaker and guess what?  It made no difference in the loudness at all.  Neither 4Ω speaker was any louder than the original 8Ω speaker.

So I back went the original setup with the pill bottle baffle for placebo effect.

I may try an 8Ω 0.5W speaker for the heck of it.  The aforementioned SF RTR set has one of those and sounds great.

Thank you everyone for all the help with this project. 

John

John, have you considered adding a bigger filter capacitor in parallel with the buck converter's output to prevent short power drops to the secondary amp?

Choosing capacitor sizes, isn't my forte, but I'm thinking maybe a 4000µF may do it, something like this.

https://www.mouser.com/Product...i7jDbygbqAvd2c3pw%3D

Maybe some else could suggest a better value than my rough guess...

@SteveH posted:

John, have you considered adding a bigger filter capacitor in parallel with the buck converter's output to prevent short power drops to the secondary amp?

Choosing capacitor sizes, isn't my forte, but I'm thinking maybe a 4000µF may do it, something like this.

https://www.mouser.com/Product...i7jDbygbqAvd2c3pw%3D

Maybe some else could suggest a better value than my rough guess...

I thought of adding a current keeper Steve.  I may try it after I try the lower wattage speaker, but the problem would probably be solved if I added a second pickup roller.  One would always be in contact with live current despite the taped over sections.   Still the cap would probably be easier.

John

John, out of curiosity, what are the microfarad and voltage values of the two bigger electrolytic caps on the buck converter?

I had the sound drop-out issue with all of the newest Legacy steam with the modified RS-Lite board.  I had to create a fix for it, and of course it involved large capacitors.

New Legacy RSL4 Sound Dropout Issue and Fix

@SteveH posted:

John, out of curiosity, what are the microfarad and voltage values of the two bigger electrolytic caps on the buck converter?

1000µF / 50v

470µF / 35v

John

@gunrunnerjohn What do you think about installing this 4000μF 35V Electrolytic in parallel with the Buck converter's output?

Should an inrush current limiting resistor be added in series with the DC+ out and the Cap's positive lead, maybe something like a 1/4 watt 100Ω?

But then connect the 2nd audio amp's input directly to the Cap positive lead?

A 100 ohm resistor would defeat the purpose of the large capacitor!  Also, the capacitor would be far more effective if it were on the input side of the buck converter after the rectification.

For the board pictured below, I'd install any bulk capacitance across the large filter cap prior to the switching section, that's the best place for the extra filtering.

Ok thanks!  That does make sense.  So then the extra cap should also be rated for 50V, like the existing 1000µF / 50V, right?

Well, it could probably be a 35V one since the most voltage you're going to apply is track power.  22V * 1.4 = 30.8 peak volts out of the bridge rectifier.

You're probably right.  I was thinking of matching the Voltage to the other 50V Cap as well as those pesky Transient Voltage Spikes I keep hearing so much about

The rating on the module is AC 5-30V DC, and DC 5V-48V, so they needed the 50V input cap rating for full range input voltage.  We're not using it that way, so no need to add the size or expense of a higher voltage rating.  Transient spikes will have no effect on the bulk capacitance.

Perfectly logical reasoning for this application.

I was joking about the Spikes.  I don't believe they are of a long enough duration to cause excessive heating in the cap, ie failure.

The bottom of my AC/DC Buck Converter board is different than the one represented on the order page.  On the one I received, the DC Input appears to be incorrectly labeled AC Input and the large capacitor is connected differently (unless I am looking at it wrong?).  Take a look:

Depicted

What I received:

John

I would put AC or DC in on the AC terminals.  Since it's a full-wave bridge, it'll handle DC just fine on the AC terminals.

@gunrunnerjohn posted:

I would put AC or DC in on the AC terminals.  Since it's a full-wave bridge, it'll handle DC just fine on the AC terminals.

Thanks John.

Good to know.

And in terms of a current keeper capacitor to be clear I could solder that to the bottom right where I labeled Lg Capacitor on the photo above.  Is that correct?

John

Yep, right across that large input cap, make sure you get the polarity correct.

@gunrunnerjohn posted:

Yep, right across that large input cap, make sure you get the polarity correct.

Of course.

Thanks again John

John

@Craftech posted:

Update:

Here's where I am with this experiment.

1.  Definitely louder sounds with either the HiLetgo or Adafruit mini amps with a 4Ω speaker (tried two different ones) powered by an AC/DC Buck converter.   Seems to work the best without any attenuation on the Lionel amplifier speaker outputs.  Input level can be controlled with the Lionel remote.  Both mini amps also have trim pots.

The problem with it is that there is an interruption in the sound when it goes across the insulated sections of the FasTrack switches (see below)

Those are necessary to prevent shorts with certain wheels (Example:  Lionel Santa Fe Super Chief RTR set).

The only way to combat the interruptions would be for me to install a second pickup on the other truck which I really don't want to do.  Maybe someone else someday may want to try that.  Frankly I have had it with messing with mini amps inside this thing.

I removed all of it.

2.  So then, despite the warnings about overloading the Lionel amp I tried two different 4Ω 3W speakers in place of the stock 8Ω speaker and guess what?  It made no difference in the loudness at all.  Neither 4Ω speaker was any louder than the original 8Ω speaker.

So I back went the original setup with the pill bottle baffle for placebo effect.

I may try an 8Ω 0.5W speaker for the heck of it.  The aforementioned SF RTR set has one of those and sounds great.

Thank you everyone for all the help with this project. 

John

UPDATE:  Tried an 8Ω 0.5W speaker (with the baffle).  Again, no difference in loudness, just a slight reduction in base response.

Will try the amp with the current keeper capacitor next.

John

Sad follow-up.

Grandson's original amp board fried.

Was able to use the HiLetgo amp fed by the AC/DC buck converter with a current keeper cap as mentioned above.  Using an 8Ω speaker (original) it sounded great and no interruptions going over switches.  Adjusted the pot on the amp to reduce the level feeding the speaker (no pad on the input from the LC engine amp) and it was plenty loud.  Better than ever.  So I ran it for awhile.

Then it derailed at a switch and shorted out popping the Sensata breaker connected to the Z1000 (usually not a problem).  Just reset it.  There are also a TVS diode attached to each end of the two loops.

Except now there is no sound at all even when put back at the stock configuration.  No Bluetooth chirp - nothing except a hum.  When Bluetooth remote is turned on the engine moves forward and backward, but the sounds are gone.  Tried the Bluetooth app on a tablet - no sounds with that either.  So engine controls work, Bluetooth works, sound does not.

Unless there is some miracle anyone knows about I am assuming I have to open up the Lion Chief engine and replace the entire amplifier board.

I knew the risks when I started this project.  My grandson is coming tomorrow so I'll let him know what happened. 

Thanks,

John

I doubt there's a miracle in the offing.

@gunrunnerjohn posted:

I doubt there's a miracle in the offing.

I think the board is $75.  I just have to find disassembly instructions.

Thanks,

John

John sorry to hear about the accident.  Good luck replacing the LC board.  Who knows, maybe the new one will be louder...

@SteveH posted:

John sorry to hear about the accident.  Good luck replacing the LC board.  Who knows, maybe the new one will be louder...

I thought of that.  At least others who find this thread will have an idea of what one faces ahead of time.

Thanks,

John