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The PS/2 coupler will certainly open on a PS/1 locomotive, they're designed to open on around 6 volts from the PS/2 board!   I suspect they've decided that the PS/1 board can support the extra current and dropped the higher resistance PS/1 coupler from the product line.  I have a bunch of them, they're handy because they still work for TMCC applications, the PS/2 couplers take out the R2LC triac if you use those.

 

gunrunnerjohn posted:
GGG posted:

The part numbers for original PS-1 are not the same as PS-2.

I was sure that had to be the case.  I didn't realize that now MTH just used the lower impedance ones.  I suppose that works, I don't know how robust the circuit that fires them on PS/1 is.

TIP31.  The same transistor that runs the Lionel Starter set DC motors on the old 103E unit.  Robust enough, especially with that huge 1000uF capacitor they use.  G

Bringing this one back from the way dead.

I'm installing a DCC system in what used to be a proto 2 engine. I would like to fire the coil coupler using the DCC board. The DCC board puts out 10.5 volts dc and the maximum amperage rating is 400 milliamps for that output. My understanding is the original proto 2 couplers were designed to operate at 6 volts.

Based on the resistance I measure across the coupler pins, at 6 volts the coupler will be pulling 2.5 amps. Obviously that seems like a lot. With my 10.5 volt output, if I tried to limit the current using a 22 ohm resistor, will the coupler not function at that point? Would the 10.5 volts alone create problems even if I'm only drawing 400 milliamps? Will it even be enough current to fire the coupler?

Won't work, you'll drop all the voltage across the 22 ohm resistor.  The PS/2 couplers get a very short pulse and they draw several amps in order to operate.

I don't think 400ma is enough to operate any coupler.  If you really want to use the coupler, you're going to have to add parts, specifically something like a high power FET to actually fire the coupler and use the DCC output to trigger it.

Won't work, you'll drop all the voltage across the 22 ohm resistor.  The PS/2 couplers get a very short pulse and they draw several amps in order to operate.

I don't think 400ma is enough to operate any coupler.  If you really want to use the coupler, you're going to have to add parts, specifically something like a high power FET to actually fire the coupler and use the DCC output to trigger it.

What he said.  The PS/2 coupler gets a fixed pulse of less than 0.1 seconds. The "physics" of an electro-coupler or solenoid mechanism is in the so-called AT-product.  AT= Amp-Turns.  Amps is Amps.  Turns is the number of windings in the coil.  The ounces/pounds of force is proportional to the AT-product.  Obviously you have no control over the number of turns in the coupler as it is was it is.  So you absolutely must generate enough Amps.  I think 400 mA might "nudge" the mechanism but not "operate" it.

I realize you're probably reading the 400 mA limitation from some product documentation.  But is this limit because the circuit itself (e.g., a specific component such as a transistor) can't deliver more current...or is there something else?  What I mean is you might be able to employ a tried-and-true inexpensive O-gauge Capacitive Discharge circuit used in solenoid-type turnout mechanisms.  In other words store up a bunch of energy in a capacitor (takes a second or so to charge up) and then rapidly discharge it to fire the solenoid.  This gets you a short burst of Amps of current which is what you need.

If you can't find specific information on why the DCC circuit has the limits you state, perhaps post a closeup photo showing the output circuit and maybe one of us can speculate as to a practical/economical solution.

Last edited by stan2004

I was afraid of that.

The 400ma limitation is in the Soundtraxx Tsunami documentation pictured here.

How about I hook up the 12V battery directly through a relay in the tender, and I use the DCC function to fire the relay. Does the 12V risk heating up the coils and damaging them? I have some CV boards I could put in there and dial it down to 6V if so. I bought them to run some lights off AC track power, would it hurt to feed them 12V DC and let them output 6V?

I'm thinking of doing a relay to turn on smoke anyway, maybe it's the solution and I can use the same type of relay for both.

16189719939443934584954820369541

CV boards (2 shown)

16189721237249130395713426748527

Attachments

Images (2)
  • 16189719939443934584954820369541
  • 16189721237249130395713426748527

Now that the identity of the protocouplers has been established, I suggest you start a new thread in either the DCC or Electrical sub-forum.  I looked at the Tsunami documentation and have questions but have little to do with MTH DCS and much to do with DCC and/or Electrical!  I think you'll find a better audience in one of those forums.

BTW, I'd elaborate up front your thoughts on the smoke unit (PS2 unit?) as they have similar hookup issues.

@stan2004 posted:

What he said.  The PS/2 coupler gets a fixed pulse of less than 0.1 seconds. The "physics" of an electro-coupler or solenoid mechanism is in the so-called AT-product.  AT= Amp-Turns.  Amps is Amps.  Turns is the number of windings in the coil.  The ounces/pounds of force is proportional to the AT-product.  Obviously you have no control over the number of turns in the coupler as it is was it is.  So you absolutely must generate enough Amps.  I think 400 mA might "nudge" the mechanism but not "operate" it.

I realize you're probably reading the 400 mA limitation from some product documentation.  But is this limit because the circuit itself (e.g., a specific component such as a transistor) can't deliver more current...or is there something else?  What I mean is you might be able to employ a tried-and-true inexpensive O-gauge Capacitive Discharge circuit used in solenoid-type turnout mechanisms.  In other words store up a bunch of energy in a capacitor (takes a second or so to charge up) and then rapidly discharge it to fire the solenoid.  This gets you a short burst of Amps of current which is what you need.

If you can't find specific information on why the DCC circuit has the limits you state, perhaps post a closeup photo showing the output circuit and maybe one of us can speculate as to a practical/economical solution.

STAN

I am looking for practical equations for design/optimization of a solenoid.  Unfortunately not train related, so I may not elaborate here.

Would you please point me in the direction of a resource?  Or email me and I would be more than happy to elaborate.



It is kind of funny how often subjects come up here that have an application to something I am working on "in real life".

V/R
BWRR

So a web search on "solenoid design" or the like and you will be overwhelmed with A-to-Z level of detail.  I was amused to find several "solenoid design calculators" which reminds me of those "LED calculators" that help you choose a resistor value to use with your LED(s) for a lighting project.

A solenoid is "just" an electro-magnet governed by fundamental physics/equations.  And, tongue-in-check, yes there actually was a dude named "Ampere" a few centuries ago.  So while everyone at some point in their life wound some wire around a nail to make an electro-magnet, the practical question is how to ballpark where to start given a specific application...such as the coil decoupling electro-magnet in a UCS activation track, or the snap-action throw of a turnout.

Without knowing your exact application, my question would be to ask if you're committed to a solenoid as the electro-mechanism.  In the context of O-gauge trains, notice how the traditional electro-magnet has been supplanted by DC gearmotors (such as the slow Tortoise switch machine  or the slightly faster FasTrack mechanism).  Not as fast as the snap solenoid action but achieves the functional objective.  I don't know if MTH did it in O-gauge but I think their HO couplers use so-called "muscle wire" where heating a wire causes it to expand/contract (rather quickly) to generate a linear force.  In many cases, inexpensive solid-state electronics and its ability to precisely meter (deliver) bursts of voltage and/or current can be used to great effect.

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