# Solid-State Postwar Whistle Relay Replacement



## gunrunnerjohn

I was over on the ERR site looking for something else, and I found this, could be interesting to folks struggling with the mechanical whistle relays.


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## T-Man

I have seen it. A back burner project. 


The parts don't match up with the diagram. What is the word Horn doing there? Isn't that connected to jp1?
I am not sure of the relay spsw 5 volt? What size are the diodes? the same as D1.

I do like the idea, but is it for coventional use or Legacy.


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## gunrunnerjohn

Well, you're right! The resistors and caps are all wrong!  I'm assuming "Horn" is telling you that's the generated horn signal that is going to switch that optical triac on and honk the horn. Seems like they're just detecting a difference in the DC offset to honk the horn. Turn the diode around and it should be good for a bell.


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## T-Man

From looking at the other two, they are similiar so I gues the 10uf and 68uf are correct. I could not get the zip files to open. They unzip but could not be read.


Here is the page under hobby corner


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## phranzdan

Wow !! I don't get it. If pin 1 of JP2 is connected to the 3d rail then during the positive alternation D1 is forward biased which will conduct through the Ired (pins 3 and 4 of the opto coupler), through the CE junction of T1 which is biased on through R1 and R3 turning the triac on (pins 1 and 2 of the opto coupler). This would make pin 2 of JP2 hot. during the negative alternation D1 is cut off as is T1. Also, C1 will be reverse biased which we all know is not a good thing for an electrolytic cap. What is connected to JP1 hot and common ? Makes no sense to me exactly how this works. Is there any more info on this? I am really curious.

Phranzdan


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## gunrunnerjohn

Did you not pick up the fact that C1 is labeled BP? That's bi-polar, aka works both ways. 

How it works?

There is a constant voltage applied to the anode of the opto from the simple DC supply comprised of D1 and C2.

As long as there is pure AC on the track, C1 does not charge sufficiently to allow the transistor to conduct, it needs about .7 volts on the base.

When positive DC is applied to the track, that capacitor then charges up and the base of T1 goes positive and turns on the transistor, thereby firing the triac. The horn is driven directly from the output of the triac and you get action.


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## phranzdan

Gunrunnerjohn: I was thinking mostly of the reverse polarity on the capacitor. I saw the + symbol on the upper plate and assumed it was an electrolytic. In 40 odd years of working in electronics, I never heard of a capacitor referred to as "bipolar". A capacitor can be polarized e.g. an electrolytic in which case polarity must be observed or non-polarized in which case the capacitor doesn't care about polarity. Consequently, the letters 'bp" meant nothing to me. Given that the capacitor is non-polarized, then it will look like a resistor to ac with a value of 10ee6/2piFC where the capacitance is in microfarads. This will support an ac voltage hopefully small enough to prevent T1 from turning on during the positive half cycle. When I get a chance, I will cobble this together and give it a try. This could probably be used to remotely turn on other things as well. 

Best regards

phrazdan


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## gunrunnerjohn

Yep, if you reverse the polarity, it would respond to the bell button on a more modern transformer. 

The term bipolar came into use recently, they used to be called nonpolarized in the old motor control days.  Remember the start capacitors on electric motors?


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## plandis

gunrunnerjohn said:


> Yep, if you reverse the polarity, it would respond to the bell button on a more modern transformer.
> 
> The term bipolar came into use recently, they used to be called nonpolarized in the old motor control days.  Remember the start capacitors on electric motors?


oh ya- I have heard that "bi" term out here in cali. LOL!

Start caps not so old-run caps for that mater...- they are still widely used in hi torque single phase motors. -boy do those stink when they go bad!


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## plandis

gunrunnerjohn said:


> I was over on the ERR site looking for something else, and I found this, could be interesting to folks struggling with the mechanical whistle relays.


John- did you happen to see what they get for this horn relay circuit?


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## gunrunnerjohn

This is from their "tech" section, they don't sell it, you have to build it. 

The only part that is a bit hard to find is the triac, this one from Digikey: http://search.digikey.com/us/en/products/S101S05F/425-2386-5-ND/720472


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## lowtechtrain

My main problem with this circuit is that it will only work if a particular rail is made positive. Please educate me if I am wrong.


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## gunrunnerjohn

I'm not sure why that's a problem, it's designed for O-gauge whistle control, and that's how it's supposed to work. You could do a little changing and have one that responds to the bell button on a modern transformer as well.


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## lowtechtrain

*Whistle unit*

I get it. It's intended for 3-rail operation. Got a circuit to roll-your own seq reverse?(besides the one at squidoo or whatever it is)


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## gunrunnerjohn

I'm not entirely sure exactly what you're asking for...


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## T-Man

Low tech, I know of both projects you are referring. I have a folder on each one and so far they are not complete. I haven't figured them out but you are welcome to try. I go with more reliable sources who are willing to discuss their projects. AT least the triac is in stock, it wasn't last time I looked.


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## rrswede

I recognize this thread is dated but would appreciate an update. 

I have two 6026 whistle chassis minus relays. The typical cost on Ebay for a replacement, including shipping, doesn't appeal to me so I am looking for a suitable solid state replacement that a tinkerer could assemble, 

Has anyone built this unit and what advice can you offer?

Thank you, swede


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## gunrunnerjohn

I've never built it, but there's no reason it shouldn't work. The issue is the solid-state relay is unobtainum. I've toyed with the idea of using a simple relay circuit with a miniature relay in a similar circuit to do the job.


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## rrswede

Thank you very much for the response, gunrunner. 

I am not certain how to interpret your term, unobtainum (a highly desirable material that is hypothetical, scientifically impossible, extremely rare, costly, or fictional, or has some of these properties in combination). If you believe there is a more direct or less costly alternative to buying a whistle relay on Ebay or building this one, please let me know. I am not versed in electronics but certainly can follow instructions from someone who is.

Thanks again, swede


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## gunrunnerjohn

I was merely point out that the solid-state relay in that design apparently is no longer available. Doubtless, it would be done with a different pick.


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## rrswede

Thanks for the clarification, Gunrunner. Now I understand.

swede


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## Mneafus

*Relay connections*

I know this thread is a little old but gunrunner would you clarify connections JP2 and jp1. Jp2 pin1 is track voltage and pin2 is voltage out of relay after it conducts I think but jp1 has me a little confused as to it function if JP2 is powering the whistle motor. Also would it be possible for you to describe just how the circuit works. I would just like to know how the circuit is rejecting the ac component and is being made to conduct on a D.C. Signal. I will be building this circuit later on, digikey has a suitable replacement solid state relay that will work. But I always like to understand circuits I build instead of just soldering parts together not understanding what makes it tick.
Thanks


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## gunrunnerjohn

Looking at the circuit, JP1 is connected to the actual track voltage, and JP2 goes to the whistle as the "output" of the whistle relay.

D1, C2, and R2 provide a source of DC for the solid state relay.

The RC network R1 and C1 detects the DC bias on the track provides the voltage to turn on T1 and energize the solid state relay.


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## Mneafus

*Whistle relay*

Thanks for the overview of the circuit, I think I'll get all the components and breadboard it and then take measurements while it's running to understand it's operation better. I have forgotten a lot of my electronic training so this will be enlightening. I am at a loss for why r1c1 detects and allows the 5 volt D.C. To bias t1, or more specifically c1s part in the biasing t1.


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## gunrunnerjohn

If there is a DC bias on the track, the bi-polar capacitor C1 will charge in a positive direction. When it gets past around .7 volts, it'll turn on the transistor at T1 and complete the circuit for the opto coupled relay.


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## Mneafus

*Whistle relay*

Ok, I had calculated voltage drops of r1 and r3 and Rt equaled DC volts applied I had not been able to account for at least .7 volts to bias the base, that explains the missing bias voltage but why doesn't c1 charge enough on the positive half wave to push the base into conduction?


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## gunrunnerjohn

Because it discharges an equal amount on the negative half-wave. The time constant of the RC network is .22 seconds, considerably longer than the 60hz waveform. With AC on the input to the RC network, the ripple is less than .5 volts, not enough to turn the transistor on. When the DC offset is sensed, the baseline voltage across the capacitor rises from zero and the transistor conducts.


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## Mneafus

*Whistle relay*

Thanks gunrunner, I have enjoyed the analysis of the relay circuit. I'll have a lot better understanding of its operation when I build it. Thanks again for the electronics review.


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## highvoltage

gunrunnerjohn said:


> I was merely point out that the solid-state relay in that design apparently is no longer available. Doubtless, it would be done with a different pick.


For those still interested in this, here is the relay from Digikey:

http://www.digikey.com/product-detail/en/sharp-microelectronics/S101S05V/425-1210-5-ND/458231


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## Mneafus

*Replacement relay*

There probably are a number of relays that electrically will work and are close in size of the package. Last week they gave me part # cla411-nd with a 4-sip package. Wonder what the difference is? Gunrunner that do you think about is?


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## gunrunnerjohn

highvoltage said:


> For those still interested in this, here is the relay from Digikey:
> 
> http://www.digikey.com/product-detail/en/sharp-microelectronics/S101S05V/425-1210-5-ND/458231


Did you note this: *Quantity Available 0*



Mneafus said:


> There probably are a number of relays that electrically will work and are close in size of the package. Last week they gave me part # cla411-nd with a 4-sip package. Wonder what the difference is? Gunrunner that do you think about is?


Probably not a good choice, note this parameter.

_AC Operating Voltage *20*-280 VAC (Vrms)_

They're also pretty expensive.

Instead of using a SS switch, why not a plain relay? Here's a 5V coil relay with 5A contacts that you can drop right into the design.

PB1172CT-ND Telecom Relay DPDT (2 Form C) 5VDC Coil

The only adjustment that might have to be made is to change the value of the 820 ohm resistor, probably drop that to around 330 ohms.


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## Mneafus

*Whistle relay*

I did recheck the digikey site and you are correct it does have a Vout operating range of 20-280rms. But I also went back and checked the original 425-1210-5-nd and it had a ac rms range of 80-120. My question is this shouldn't the cla numbered relay work sufficiently if it's operating range is a lot lower than what's called for in the bill of materials? And these are also available although not cheap by my standards. I talked again to digikey and this person said the 255-1569-nd would be a better match for the ac range of our whistles but how could the original design be so far off the operating range unless it was never researched properly.

Confused in okie land


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## highvoltage

gunrunnerjohn said:


> Did you note this: *Quantity Available 0*...


Oops, missed that.


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## gunrunnerjohn

Since I haven't tried any of these, I can't comment on their suitability, though I suspect they will probably work. I have some large 25A rated solid-state switches intended for 120 VAC, they drop about 2 volts when used with 18 VAC from a train transformer.

I like the relay as it drops zero volts and is cheaper to boot.


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## Dmm

so verry sorry to bump a very old post, i have made 3 of these
none works thus far.

only thing i can think is i am using 47uf 50v and not 35v for C2, and also 10uf 50v B.P. for C1 and not 35v. 
would this make it not work?

im gonna try and make it how the pcb looks next i guess, ill keep yah posted.

any info would be helpful.


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## gunrunnerjohn

I can't imagine that the voltage rating is the issue, that shouldn't make any difference.


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## T-Man

Are you trying to run a whistle or a horn?


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## Mneafus

gunrunnerjohn said:


> I can't imagine that the voltage rating is the issue, that shouldn't make any difference.


Gunrunner, I had discussed this very issue with you some years ago and my attempt at the time failed. But I’m sure it was assemblers error, mine. I do have a question about this circuit mod you had touched on then. You said probably a mechanical relay could sub for the solid state relay but a change of the resistor would be necessary. What would the resistor value need to be in this circuit mod in your opinion and would the rest of the circuit stay the same?


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## Dmm

whistle


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## Dmm

good god what a pain, I found out what's goin down with it. resistors should be 10k. no resistor on the relay.

ill post some picts and a draw up of it later.

thus far i have made two, so ill post what works the best and is the cheapest.

btw i have them all on relays 3v-5v-12v work fine so far. 
it can also run dc can motors for the whistle(if you replace the ac motor for some reason)


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## Dmm




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## Dmm

Dmm said:


> View attachment 573972


so in total 7 parts.

2x 10k resistors
10uf 50v
47uf 50v
2n3904
1n400* resistor
3v-5v-12v relay

please post results.


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## Mneafus

Dmm said:


> View attachment 573972


This was my final take on this circuit after talking with gunrunner a few years ago but didn’t try it after my first failure. Can you share the part number for the relay and source and do you plan on making a PCB for this.


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## gunrunnerjohn

Without the resistor that you eliminated, you will fairly quickly cook the diode in the S101V05V. One issue with a replacement relay is what coil voltage to use. Conventional stuff runs at fairly widely varying voltages, depending on the exact locomotive.


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## Mneafus

gunrunnerjohn said:


> Without the resistor that you eliminated, you will fairly quickly cook the diode in the S101V05V. One issue with a replacement relay is what coil voltage to use. Conventional stuff runs at fairly widely varying voltages, depending on the exact locomotive.


I took a second look at the schematic and his post and realized he eliminated the diode resistor just after my post. Gunrunner, I guess I’ll reference my last question I posted to you. What resistor would you use for the diode protection if you replaced the obsolete relay. I’ve burned up a handful of pencils trying to calculate that circuit.


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## Mneafus

gunrunnerjohn said:


> Without the resistor that you eliminated, you will fairly quickly cook the diode in the S101V05V. One issue with a replacement relay is what coil voltage to use. Conventional stuff runs at fairly widely varying voltages, depending on the exact locomotive.


The varying voltage was the part that has caused me a problem but would a voltage regulator inserted in the circuit after the diode and resistor matched to the relay coil work? And I would greatly appreciate it if you could give me some insight on how to calculate for that resistor if you would.


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## gunrunnerjohn

Truthfully, I'd probably use a 5V regulator so that I could use a 5V relay and be assured that it worked every time. I'd also probably replace the 2N3904 with a FET for a lower drop across the part. Don't know that I have the time to totally design a new circuit, not to mention that I'd want to test it before I actually presented it as a solution.

Of course, there's always the circuit that Lionel uses in the more modern conventional set locomotives, just drop a relay there in place of the motor. A little experimenting should yield a working whistle relay circuit.


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## Mneafus

gunrunnerjohn said:


> Truthfully, I'd probably use a 5V regulator so that I could use a 5V relay and be assured that it worked every time. I'd also probably replace the 2N3904 with a FET for a lower drop across the part. Don't know that I have the time to totally design a new circuit, not to mention that I'd want to test it before I actually presented it as a solution.
> 
> Of course, there's always the circuit that Lionel uses in the more modern conventional set locomotives, just drop a relay there in place of the motor. A little experimenting should yield a working whistle relay circuit.
> View attachment 573992


Can you tell me what the unlabeled component would be I don’t recognize that.


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## Mneafus

Mneafus said:


> Can you tell me what the unlabeled component would be I don’t recognize that.


Darlington correct?


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## gunrunnerjohn

That would be a Darlington transistor, a TIP127 would probably be a good choice with sufficient power handling.


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## Dmm

gunrunnerjohn said:


> Without the resistor that you eliminated, you will fairly quickly cook the diode in the S101V05V. One issue with a replacement relay is what coil voltage to use. Conventional stuff runs at fairly widely varying voltages, depending on the exact locomotive.


i can find the S101V05V, at over 5 bucks a pop. its a no go. so far i have used just relays, 3v-5v-12v all work fine(why i have no idea) I might put a diode to stop any flyback from the coil. perhaps a snubber circuit? Im gonna hold down the button for 30 mins and see if i can't (let the smoke out).


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## T-Man

A picture would be nice.


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## Dmm

T-Man said:


> A picture would be nice.


ok, but don't rip my head off cause its gonna be ugly. standby.


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## Dmm

this is with a npn-d, has two tone control and can also do dc can motors.

so far from about 9-25 volts and no problems, im gonna try it with every post war loco i have.

once i figure out how to make it into a schematic ill post that.

the part list so far

ac/dc horn relay for post war tender
470uf 50v
100uf 50v
10uf 50v
1n4004 diode
bc517 or MPSA14 npn Darlington Transistor
2x 10k resistor
12v coil 220vac 3a relay

It seems to work way better than the 3904 transistor version.

i have a few tip120's laying around(50+) so i am gonna give them a go too.


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## T-Man

Looks good! What are you using to activate the whistle if the coil is 12V DC?


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## Dmm

T-Man said:


> Looks good! What are you using to activate the whistle if the coil is 12V DC?


that's the thing, just a normal type-kw transformer. I don't get why it will turn on a 12v coil at 5-6 volts ac from the transformer..abit cranky it wont two tone at that power. but at around 9-10 volts no issues, that even with a 681 pulling it at a crawl. 

more testing must be done! Im gonna toss everything i can at it. i have almost every Lionel transformer made. so if anyone has any suggestions let me know, ill also give it a go on some no #67-166-167 whistle controllers.


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## T-Man

This is the 
90's version that John supplied the circuit for. This is a DC motor so the connection is direct, WIth a relay you can run the AC whistle. The darlington is a KSP13.


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## gunrunnerjohn

Dmm said:


> i can find the S101V05V, at over 5 bucks a pop. its a no go. so far i have used just relays, 3v-5v-12v all work fine(why i have no idea) I might put a diode to stop any flyback from the coil. perhaps a snubber circuit? Im gonna hold down the button for 30 mins and see if i can't (let the smoke out).


The lower voltage relays are getting run way over their coil current dissipation ratings, I suspect they will fail far sooner than the 12V relay. If the relay coil is seeing roughly 10-12 volts DC, it's dissipating A diode to prevent the transistor from being zapped by a coil spike is a good idea. The reason the 12V relay operates at 6-7 volts AC is the cap charges to 1.4 times the AC RMS value, so there's enough voltage to pick a 12V relay.

Let's say the 3V relay has a coil resistance of 100 ohms and draws roughly 30ma at 3VDC, that's about .1 watts of dissipation. However, if that coil sees 10 volts across the 100 ohms, now the power dissipation is 1.0 watts, ten times the normal power dissipation! All that extra power is released as heat in the relay coil.


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## Dmm

T-Man said:


> This is the
> 90's version that John supplied the circuit for. This is a DC motor so the connection is direct, WIth a relay you can run the AC whistle. The darlington is a KSP13.
> 
> 
> View attachment 574047
> 
> 
> View attachment 574049
> 
> 
> 
> 
> 
> 
> 
> 
> View attachment 574050



is the small cap a 1uf 50v cap?


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## gunrunnerjohn

If you're talking about this circuit, yep it's a 1uf 50V.


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## Lemonhawk

John, does that 1 uf cap need to be non polarized? Looks like the power can be either A/C or DC.


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## gunrunnerjohn

Looks like it should be a non-polarized cap from the usage.


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