Tagged With "diode"

Topic

diodes to slow down hill speed

gptom ·
which diodes should I use to slow my train? do you have a part number or specs? Thanks Tom
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Re: Diode Question

Texas Pete ·
Originally Posted by gunrunnerjohn: A little spendy at $4/ea. No kiddin'! 10 O22/513*, 3 bulbs each, that's $120 led bill. I'll pass. Got the 100 diodes John recommended coming, lost in Michigan right now courtesy of USPS. I have a question as to where to install them when they arrive. Looks like the one for the switch lantern will have to go inside the switch motor, but the schematic suggests that the controller diodes can go between the two outer posts and the center post on the switch...
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Re: Diode Question

ADCX Rob ·
How about 100 for $3?
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Re: Diode Question

Texas Pete ·
Those would be great if they're small enough. Thanks, Rob. Pete
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Re: Diode Question

gunrunnerjohn ·
I'm a fan of higher voltage ratings on the diodes to protect from spikes killing them. 100 x 1N4003 1A 200V Rectifier Diode - 4 Days Delivery $4.39 with free shipping from a US supplier.
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Re: Diode Question

Texas Pete ·
Thanks, John. Pete
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Re: Diode Question

Dale Manquen ·
When you install the diodes, hook up half of them in one direction, and the other half in the opposite direction. This will keep the current in the source transformer from having a big DC component (which increases transformer heat and can reduce the maximum power that the transformer can supply.)
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Re: Diode Question

gunrunnerjohn ·
Dale, long time, no see. Glad to see you back.
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Re: Diode Question

TrainLarry ·
Drop-in LED replacements are another option. Long life and less heat, the perfect combination. Larry
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Re: Diode Question

gunrunnerjohn ·
A little spendy at $4/ea.
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Re: diodes to slow down hill speed

Consolidated Leo ·
Carl: Not a problem. I appreciate that there are many ways to approach a situation like this. I prefer to operate trains with the controls in front of me. I'm not sure that I want to get into remote controllers or tethers or wifi on a smart phone. That just doesn't appeal to me. I've seen that you contribute a great deal to the forums and that's excellent. I think ideas from experienced individuals is what makes all this reading and typing worthwhile. We have to let what advice we give speak...
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Re: diodes to slow down hill speed

bdobson ·
I use bridge rectifiers on a dial that I can add a rectifier at increments based on the size/speed of the train. The switch is connected to 2 sections of track. Guy by the name of Dearborn Dave explained it well on another forum. Being able to adjust the values is great so you can set it and forget it and train requires full power on an up hill and power reduction on a downhill Using handles of a zw is a bad idea and many have spoken of it numerous times on what types of bad things happen...
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Re: diodes to slow down hill speed

bmoran4 ·
Not necessarily a bad idea, nor particular to the ZW - one just needs to account for the crossing of power districts. In fact, many of Lionel's own layout designs used multiple power districts. This one also uses a resistor on the downgrade.
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Re: diodes to slow down hill speed

stan2004 ·
Not sure we're talking apples-apples. If the train is backing up the hill, say the caboose trips the top-of-hill sensor. The way your relays are configured, the top-of-hill sensor always takes precedence (if both sensors are tripped simultaneously). So the voltage would drop on the grade and the engine might get starved of voltage and perhaps even stall! Likewise, you might have a MU consist or even a pusher engine configuration. In such cases, as soon as the lead engine reaches the...
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Re: diodes to slow down hill speed

Dennis LaGrua ·
Many schemes to slow engines on the down slope are presented here but I'll still stay with my 1 ohm 5 w resistor to the center rail on the insulated 48" section of the down slope. This basic technique only works on the down direction but that's the way I keep that loop running. If I want to reverse direction I can also make the up side an insulated block and interchange the series resistance and track voltages to each block with a DPDT switch. Simple and cheap.
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Re: diodes to slow down hill speed

Consolidated Leo ·
Guilty as charged. It's not a perfect solution for all possible scenarios. I was just thinking of running in conventional mode with a lead engine up front and moving forward. Even then, any lighted caboose or passenger cars could suffer from changing voltages as they move on the grade. But that might be okay. It just seemed to me rather awkward not to be able to adjust for uphill / downhill movements. I can't think of how you would cover any other situations and still keep it simple and cheap.
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Re: diodes to slow down hill speed

stan2004 ·
No charges were filed. But you did ask for feedback on your idea. I think the take-away is that diodes and/or bridge-rectifiers suitable for train usage have become remarkably inexpensive and readily available. Likewise, relays have become remarkably inexpensive hence practical to incorporate into layouts for whatever reasons. When I saw your 3-relay diagram I immediately thought of the 4-channel relay modules that end up less than a buck per relay (free shipping from Asia), and even has...
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Re: diodes to slow down hill speed

Consolidated Leo ·
Wow! $2.89 !!! That's a great price! But my preference is for the 5v versions. Those I have run directly off the I/O pins of the Arduino. I've also noticed a newer design floating around on eBay. I can't be sure but just from the pictures and the look of the silkscreen I think they're different. Just the idea of being able to carry 10 amps at 30 volts makes these a great choice for the trains.
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Re: diodes to slow down hill speed

stan2004 ·
Did I hear you say 5V?
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Re: diodes to slow down hill speed

Consolidated Leo ·
Thanks! You've got the magic touch when it comes to eBay searches. I looked earlier and couldn't find the ones with the "hi-low" trigger option. I've just placed an order for 4. With a discount and free shipping it comes to $10.20 total. Wow!
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Re: diodes to slow down hill speed

Consolidated Leo ·
My order of relay boards from Asia arrived today (about 4 weeks). I hooked one up to my latest Arduino signaling experiment on a breadboard. I added some code to make them turn on and off with various changes in signal aspect. They worked perfectly. Next step is to get some RS485 chips included in the circuit (SN75176BP) so that I can send serial messages between multiple processors.
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Re: diodes to slow down hill speed

gptom ·
I assembled a bunch of diodes and a heat sink. Then I took off for York and found a bunch of prewar 95 speed controllers. I went old school. I originally had 2 blocks but added a 3rd for the roll out. works beautifully!
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Re: diodes to slow down hill speed

gunrunnerjohn ·
Command operation with cruise control solves all these issues with no diodes or resistors.
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Re: diodes to slow down hill speed

Train Nut ·
So does a sledgehammer.... ????
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Re: diodes to slow down hill speed

BOB WALKER ·
A sensor at the start of the hill which switches to lower track voltage on the slope would seem to be an easy fix. The assumption is that conventional control is being used.
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Re: diodes to slow down hill speed

stan2004 ·
If command-control is not an option, you could install engine electronics that has built-in speed control. Not plug-and-play and not low-cost but a MTH PS2/PS3 upgrade kit could be installed. I'd expect the conventional speed control in PS2/PS3 going downhill (and/or uphill) would be as good as the 95 rheostat or the diode method. I can't imagine anyone doing this since the rheostat or diode methods are just a few bucks. There was a short window of time when command control was just taking...
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Re: diodes to slow down hill speed

Ted S ·
The diode / rheostat method is the only one that works with traditional AC motors. When they make LionChief Plus versions of the 2037 and 2034, then I'll surrender ;-)
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Re: diodes to slow down hill speed

stan2004 ·
Wherever you read about how/why of the paired-diode drop method presumably also explained you can use a bridge-rectifier which has 4 diodes. A bridge can simplify inter-connections and can make for neater assembly/mounting as some packages have mounting holes vs. loose individual diodes. This photo recycled from another thread about diode dropping. 10 Amp bridge rectifiers are about 30 cents on eBay free-shipping from Asia. For example, KBU1010 is a widely available part number that you can...
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Re: diodes to slow down hill speed

gptom ·
Stan2004, thanks for the great info Is a heatsink necessary? or just hanging loose in the air
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Re: diodes to slow down hill speed

RoyBoy ·
Depends on how much current you draw through them. The 10 amp maximum spec is generally for diodes that have heat sinks mounted.
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Re: diodes to slow down hill speed

Drummer3 ·
A forum member sent me this a while back. Hope it helps.
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Re: diodes to slow down hill speed

stan2004 ·
Unfortunately there is some tedious do-the-math on the need for heat-sinks, how big they need to be, etc.. I figure you'll probably need more than 1 bridge rectifier anyway, so why not use some scrap metal to double-duty as a mechanical mounting platform and a electrical heatsink. As shown in the photo, I use "scrap" 1/8" aluminum sheet and mount the bridge rectifiers with #4 machine-screws into threaded holes. But whatever you have lying around will work. The purists will say to use...
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Re: diodes to slow down hill speed

Ted S ·
My $.02 here... why wouldn't the original poster use something like a No. 95 rheostat, or other adjustable resistor, instead of rectifiers / diodes? This would allow him to adjust the resistance for varying train lengths and locomotive types. Note I haven't actually done this, but I'm pretty sure I read some old reference books that suggested this is how it was done "back in the day." What are the pros and cons? Are the rectifiers simply newer technology that wasn't available in the '50s? Is...
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Re: diodes to slow down hill speed

Moonman ·
Make use of the four channels on a ZW or Z4000 transformer. A for level or main(variable), B for UP and C for down, with B & C being fixed, which leaves the D handle free. A lot easier to tickle the UP & DOWN voltage for a different set of cars or engine change.
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Re: diodes to slow down hill speed

Dennis LaGrua ·
Here's my caveman conventional approach. Going up full 12V from the transformer. Going down a 48" insulated section supplied by track voltage with an inline 5W 1 ohm power resistor going to the center rail. Works fine.
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Re: diodes to slow down hill speed

Consolidated Leo ·
What happens if the train is going in the other direction? Then this uphill / downhill terminology is bogus with respect to the track. You need to be able to turn it around. Switches would work if you don't mind the responsibility of manual operation. But some track sensors and relays could change the orientation of the diodes based on the trains direction. I would think that a top-of-the-hill / bottom-of-the-hill sensor and a cheap asian relay board to steer the diodes would be all that is...
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Re: diodes to slow down hill speed

Moonman ·
Reverse voltage for B & C handles. A is still variable and level. Hills are not a problem with command controlled engines with cruise control. But, many insist on playing these games and running conventional engines in ways they weren't designed to be operated. So be it, become a good engineer and work the throttle(s).
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Re: diodes to slow down hill speed

ADCX Rob ·
Rheostats are the way to go. Quickly adjustable on the fly and when changing out your consist/motive power, and avoids the issue of fault currents across the secondary windings.
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Re: diodes to slow down hill speed

Consolidated Leo ·
That's an unusual way to look at it. And just how are conventional engines designed to be operated? The last time I checked, they use a variation in voltage to run at different levels of power and speed. I believe the OP asked about using diodes to vary the track voltage on a downhill grade. I would guess that he wants to avoid having to work three different throttles at the same time. Automation on the layout is not breaking any rules that I'm aware of. C'mon man!
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Re: diodes to slow down hill speed

ADCX Rob ·
Next thing you know the rebels will be controlling blocks & signals with insulated sections & relays.
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Re: diodes to slow down hill speed

Consolidated Leo ·
Since going uphill will use full power, downhill is the only direction that would require the voltage reduction diodes. But you still need 2 sensors. One at the top of the hill and one at the bottom. These could be anything that delivers a positive DC voltage to a 5 or 12 volt relay module. Noise should not make any difference because the relays are setup to hold their position from one sensor to the other. When the train reaches the top of hill sensor, the first relay kicks in. That sends...
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Re: diodes to slow down hill speed

Moonman ·
Re: diodes to slow down hill speed
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Re: diodes to slow down hill speed

Bob Delbridge ·
Unless I missed it the OP didn't say anything about multiple engines. But when I first read his post my initial response was "Just back off the throttle when going downhill". The problem with installing diodes is they also affect the speed going uphill or on a flat track.
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Re: diodes to slow down hill speed

stan2004 ·
In all likelihood, the OP could use some kind of resistor or variable-resistor/rheostat. But that was not Tom's question. To answer your question, the diode method provides more stable voltage drops under varying loads. By loads, I mean current required by the engine to pull itself and whatever loads. So here's where the eyes glaze over. Let's say a train requires between 1-3 Amps of current. A diode will drop 0.8-0.9V as shown in the datasheet. A resistor that drops 0.8V at 1 Amp (i.e., a...
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Re: diodes to slow down hill speed

stan2004 ·
Agreed going the other direction up hill would apply full track power, but wouldn't the train eventually trip the top-of-hill sensor and lock in the track lower voltage until the train makes a complete loop and trips the bottom-of-hill sensor?
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Re: diodes to slow down hill speed

Consolidated Leo ·
You are correct. This condition, although unplanned and annoying, does not matter. Since there will be no train on the grade when this occurs. When the same train or even another train trips the bottom-of-hill sensor, full power would be restored. And if a train should be going in the other direction (downhill), tripping the top-of-hill sensor again will still apply the reduced voltage. Since the diode/rectifier circuit would be activated by that annoying condition, I thought that maybe...
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Possible use of TVS diodes recommended for model railroads that have engines with sensitive control electronics.

pro hobby ·
Possible use of TVS diodes recommended for model railroads that have engines with sensitive control electronics. On my MTH DCS control system I have installed TVS diodes at every individual track feed to my track. In addition I install a TVS diode at every output terminal of all my MTH DCS TIUs. Since I use Passive control it is not necessary to protect the TIU input terminals. Also possible is the addition of TVS diodes on the track pickups of every scale engine. In addition I have also...
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Best place to locate TVS Diode in regard to MTH TIUs.....

Junior ·
Hello Everyone... I need your help. My control panel is built (Yaaaa!) and I'm at the point of wiring it all together. I am going to include TVS diodes in my wiring scheme; but there appears to be 2 camps on where best to locate them. I am using PW Lionel ZWs that feed MTH TIUs (I'm already planning on having circuit breakers between the ZWs and the TIUs). Many model railroaders place the TVS diodes across the terminals on the transformers themselves; which in my case would between the ZWs...
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Diode in Series with E-Unit

GeoPeg ·
I am rebuilding a 602 Seaboard, owned since day 1. There is a diode in series with the non-grounded end of the coil on my E-Unit, p/n stamped on the diode is 86-51-3, equivalent appears to be 1N4004, a 600v 1amp diode. With the diode in the circuit, the e-unit buzzes at an annoying 30hz rate - by jumpering the diode, the e-unit solenoid smooths out nicely at 60hz. Has anyone ever seen this before? Any ideas on why it might be there? It's certainly not in any of the wiring diagrams I have seen.
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TW Transformer diode replacement

ajc ·
I just joined ,---- searching for info on replacing original copper oxide diode with silicon diode in a TW transformer. Plenty of info on other transformers but very little on TW. I saw a few threads and a picture from TMACK back in January 2012. After reading many conflicting articles about how to measure the original copper oxide diode and the diode direction installation for silicon, can any one tell me where to find detailed info on how to install it. Is the picture from Tmack see...
 
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