Recommendation Wanted for DC step-up transformer

Do you know how much current the smoke unit uses?

A transformer only works on AC, so you can't use a transformer. Depending on your current requirements, you might be able to use a step-up DC-DC converter.

You can find plenty of cheap ones on eBay, but I have always had good experiences with Pololu products. Here is a 15V output converter that is rated for 6A continuous input current.

Something is wrong here. 12.5 amps will run about 6 trains with smoke units. A typical fan motor is rated for between 3 and 5 volts.

Pete

@Professor Chaos posted:

Do you know how much current the smoke unit uses?

A transformer only works on AC, so you can't use a transformer. Depending on your current requirements, you might be able to use a step-up DC-DC converter.

You can find plenty of cheap ones on eBay, but I have always had good experiences with Pololu products. Here is a 15V output converter that is rated for 6A continuous input current.

You are correct, the term "transformer" is technically incorrect.

Thank you for the link.  The device looks promising.

George

@Norton posted:

Something is wrong here. 12.5 amps will run about 6 trains with smoke units. A typical fan motor is rated for between 3 and 5 volts.

Pete

Yes, but I have info from the MTH Parts dept. that suggests 12V is the minimum for this PS1 item.  And 15V is better.  Plus, it's not the fan that fails to perform - it's the smoke unit (heater) itself that isn't generating smoke at 12VDC.  It does work at 15VAC.

George

@G3750 posted:

...

1. Can anyone recommend a DC step-up transformer to get 12VDC to 15VDC (or an adjustable value)?

Taking your question at face-value, you can get remarkably inexpensive DC-to-DC step-up "transformers" (oh, all right, converters) with adjustable output:

So these are less than $3 each and include screw-terminals so soldering may not be required.  The previously linked example is indeed more compact and potentially puts out more power (I'd have to study the specs more) but at $25 each and apparently requiring soldering...yikes!

That Pololu board is hopelessly overpriced!  For the slight difference in it's specifications, it makes no sense to spend that kind of money.

@G3750 posted:

I have acquired a brand new MTH PS1 fan-driven smoke unit (part # AA0000011).  The original thought was to drive it with my Mean Well LRS-150-12 (Input: 120 VAC  Output: 12 VDC, 12.5 A) power supply.  I have determined that 12VDC isn't quite enough power to make it smoke (fan does run).  I was able to get to function correctly at 15 VAC (it will run on A/C or D/C).

I'm curious how you determined the MTH PS/1 smoke unit doesn't work on 12VDC.  That flies in the face of my quick test here.  I tried a second one with the same results.  AAMOF, I've previously run these on 12VDC and had no issues.

@stan2004 posted:

Taking your question at face-value, you can get remarkably inexpensive DC-to-DC step-up "transformers" (oh, all right, converters) with adjustable output:

So these are less than $3 each and include screw-terminals so soldering may not be required.  The previously linked example is indeed more compact and potentially puts out more power (I'd have to study the specs more) but at $25 each and apparently requiring soldering...yikes!

Yikes!  I didn't realize it was that expensive.  

By the way, I have been informed that the PS1 smoke unit draws 0.75-1.0 amps for those of you keeping score at home.

Thanks to everyone that chimed in!  Stan2004, that suggestion looks like a winner!

George

@gunrunnerjohn posted:

I'm curious how you determined the MTH PS/1 smoke unit doesn't work on 12VDC.  That flies in the face of my quick test here.  I tried a second one with the same results.  AAMOF, I've previously run these on 12VDC and had no issues.

I think the only reason it's emitting smoke is that you're squeezing it in that vise.  That's cruel! 

Mine simply wasn't producing smoke at that voltage until I partially blocked the stack with a rag.  Why?  I don't know, but that's what was happening.

George

I am curious about your choice of the MTH PS1 AA-0000011 smoke unit.  Apparently these are $50+ each...and you're planning on 4 units?  Can you share the application - presumably this is NOT for installation in an engine or rolling stock?

So here's the thing.  While you can indeed hook it to a DC power supply, the PS1 smoke unit has a clever voltage regulator circuit - considering it was designed in the last century.

There are 2 smoke heater resistors.  The on-board circuit uses the track voltage to "decide" whether to use one or both resistors.  The circuit has been posted and discussed many times in previous OGR threads and I suppose we can re-visit the component-level nitty-gritty if need be.

The upshot is you may find that when operating with DC voltage, there is a range of voltage where you get LESS smoke as you increase voltage!  And the behavior will be different between AC and DC.  So, for example, it could be that going from 12 to 15V AC increases smoke to your requirements, but that same increase from 12V to 15V DC produces less smoke! 

So back to my original question about how committed you are to using the AA-0000011.

There are other fan-driven MTH (and others) smoke units that don't have the PS1 regulator circuit and instead give you direct connection to the smoke heater resistors.  In which case more voltage will guarantee more smoke - and 15V AC will produce the same amount of smoke as 15V DC.

Apparently you got/bought a new PS1 smoke unit...but if you already had the 4 units I'd consider modifying this voltage regulator part of the circuit to give direct access to the heater resistors.  It can be a messy affair, cutting wires or circuit board traces, soldering, etc..

That's odd, are you sure you gave it enough fluid?  I put about 3/4 of a dropper into this one for the test.  I've never seen one of these that wouldn't produce prodigious smoke with 12VDC.

@G3750 posted:

By the way, I have been informed that the PS1 smoke unit draws 0.75-1.0 amps for those of you keeping score at home.

.60 amps at 12 volts, see previous post.   It draws .5 amps at 18VDC, and even better smoke.  There is an on-board regulator that switches gears around 13 volts AC and 16 volts DC, then the current drops.

I'd use the PS/2 smoke unit and a lower voltage DC power supply.  For the fan, you can simply use a couple dropping diodes from the heater voltage.  The heater at 8 ohms will require from 7 to 9 VDC to product a lot of smoke, the fan will run on anything from around 3V to 5V and produce a nice air stream.

FWIW, the actual behavior of the one I have in my vise in the shot above didn't regulate down until 16 volts DC, then the current dropped a bunch but still plenty of smoke.  On AC (pure sine wave), at around 12.5V the switch occurs with the regulator circuit.

What he said.

And with similar pricing (less than $5), you can get a DC-to-DC step-down converter module.  To keep things simple, no soldering, etc., you could use 2 step-down converter modules both powered by your 12V DC supply.  One would be set to 7-9 VDC as GRJ suggests to power the heater resistors.  The other would be set to 3-5V DC to power the fan motors.

One DC-to-DC step-down module could certainly power all 4 fan motors.  From power limitations driving 4 heaters with 1 DC-to-DC step-down module may be pushing it (depending on which converter you have) so maybe you use 2 converters and each powers 2 heaters.

Plus, I'd think the PS2 smoke units would be more readily available (and less expensive) than PS1 smoke units?

Addendum:

For about $3, you can get a DC-to-DC step-down converter with a built-in digital voltmeter!

@stan2004 posted:

I am curious about your choice of the MTH PS1 AA-0000011 smoke unit.  Apparently these are $50+ each...and you're planning on 4 units?  Can you share the application - presumably this is NOT for installation in an engine or rolling stock?

So here's the thing.  While you can indeed hook it to a DC power supply, the PS1 smoke unit has a clever voltage regulator circuit - considering it was designed in the last century.

There are 2 smoke heater resistors.  The on-board circuit uses the track voltage to "decide" whether to use one or both resistors.  The circuit has been posted and discussed many times in previous OGR threads and I suppose we can re-visit the component-level nitty-gritty if need be.

The upshot is you may find that when operating with DC voltage, there is a range of voltage where you get LESS smoke as you increase voltage!  And the behavior will be different between AC and DC.  So, for example, it could be that going from 12 to 15V AC increases smoke to your requirements, but that same increase from 12V to 15V DC produces less smoke!

So back to my original question about how committed you are to using the AA-0000011.

There are other fan-driven MTH (and others) smoke units that don't have the PS1 regulator circuit and instead give you direct connection to the smoke heater resistors.  In which case more voltage will guarantee more smoke - and 15V AC will produce the same amount of smoke as 15V DC.

Apparently you got/bought a new PS1 smoke unit...but if you already had the 4 units I'd consider modifying this voltage regulator part of the circuit to give direct access to the heater resistors.  It can be a messy affair, cutting wires or circuit board traces, soldering, etc..

Stan,

Great questions and I will address your points individually.

First, the application:  I am building a steel mill, specifically an Open Hearth (OH).  Such a mill has a number of ovens;  Weirton Steel's had 14.  I am building 4 ovens.  The effect I am trying to replicate with LEDs and a smoke unit is shown below.

My first experiment was with a Seuthe No. 7 smoke unit.  It was anemic, at best.  Recalling MTH's reputation for high output smoke units, I went onto their parts website and asked for a recommendation.  That's how I got the AA0000011.  I have bought 1 just to try it out.  And yes, they are expensive.  I am unaware of any previous discussions of this smoke unit or how it actually operates.

I am very interested in learning more about your statement:

"There are other fan-driven MTH (and others) smoke units that don't have the PS1 regulator circuit and instead give you direct connection to the smoke heater resistors.  In which case more voltage will guarantee more smoke - and 15V AC will produce the same amount of smoke as 15V DC."

Please tell me more.  I'd love an easier / simpler / better / less expensive alternative.

Thank you!

George

This is what I use in all my upgrades if it fits.  I buy the separate threaded brass cup and solder my custom stack extension to it, then mount it on the smoke unit.

@gunrunnerjohn posted:

That Pololu board is hopelessly overpriced!  For the slight difference in it's specifications, it makes no sense to spend that kind of money.

Usually the difference is buying from a US importer, instead of waiting for a package from China.

Well, that's a little more than the usual price margin.  FWIW, I've always found that Pololu is overpriced, but sometimes they have stuff you can't get elsewhere.

@cjack posted:

Usually the difference is buying from a US importer, instead of waiting for a package from China.

In this case, it's from a US manufacturer instead of a Chinese import.

The board I linked (which is $19.95 for the fixed-voltage version, not $24.95) may well be overkill for 12 to 15 V step-up for this application, and have safety features you don't need. But consider that you're getting a fully-specified product with complete documentation and support.

It does appear that Pololu's prices have gone up recently;  they have a blog post discussing their issues.