Turnout toggle/capacitor control circuit from the old Atlas forum?

[mmagliaro]

Many moons ago, somebody used to post (on the old Atlas forum) a clever trick for controlling
turnouts that involved putting a capacitor and LED in series with the turnout motor (I think these were for
a Tortoise, but I am not sure about that).  As I recall, it relied on the fact that
when you flipped the toggle, initially, the capacitor was a dead short so current flowed and the switch machine
moved, but then the capacitor charged up, shutting OFF the switch machine and somehow lighting an LED
to indicate the direction.
And I think the guy who used to post it named the idea according to his 3 initials, the first of which was a "G".
Okay, that's a rambling mess, but that's all I can remember about it.  Does anybody remember this circuit?

[peteski]

Many moons ago, somebody used to post (on the old Atlas forum) a clever trick for controlling
turnouts that involved putting a capacitor and LED in series with the turnout motor (I think these were for
a Tortoise, but I am not sure about that).  As I recall, it relied on the fact that
when you flipped the toggle, initially, the capacitor was a dead short so current flowed and the switch machine
moved, but then the capacitor charged up, shutting OFF the switch machine and somehow lighting an LED
to indicate the direction.
And I think the guy who used to post it named the idea according to his 3 initials, the first of which was a "G".
Okay, that's a rambling mess, but that's all I can remember about it.  Does anybody remember this circuit?

The only similar circuit I know of for a stall motor (Tortoise) switch machine doesn't use capacitors.  It is a circuit we use on friend's layout.



The motor windings have fairly high resistance, so even when stalled, it only consumes several mA. Perfect as current limiting resistor for the series-connected LED indicators.  The way this works is when stalled, the indicator LED is brightly lit. When the machine is in motion the spinning motor (due to BEMF) uses only fraction of the stall current, so the LED indicator flickers dimly. Then when it stalls at the end of the throw, the LED again shines brightly.  That is a nice feature as it shows whether the machine is still in the process of throwing the points, or finished. Also more LED pairs can be wired in series, so you can have local and remote indicators (assuming that the supply voltage is ample enough to handle the extra 2V per pair drop across the LEDs.
 
Like I mentioned, we have more than a dozen of these on friend's layout, and they have now worked flawlessly for close to 2 decades.  I recall Rasputen some time ago mentioned that the motor can produce voltage spike of over 200V but in our experience we have not had any buredn out LEDs.

[reinhardtjh]

The other one that was discuss often was the super secret BCD setup for Kato Unitrack switched.  It was G. R. Stilwell that had it and you had to message him to get a PDF with the details.  He passed a number of years ago and the method became more public.

It's nothing spectacular, pretty much anyone that understands RC circuits would have figured it out.  I never understood why all the secrecy.

I have the PDF, I think I got it from TrainBoard but it's no longer available there.

[Sokramiketes]

Reinhardt has what I remember, for Kato Unitrack turnouts.  It had to do with the permanent magnet set up they use. 

I don't see it working the same with the Tortoise motor, as it takes too long to move. 

Another option is feeding power to both outside pins (1 and on the Tortoise through 2.2k resistors.  Then just ground pin 1 or 8 to move it the direction you want it to go.  We use this with a "switch key" on Modutrak so that we don't have live buttons.  The key is just a shorted out RCA plug. 

[reinhardtjh]

I don't see it working the same with the Tortoise motor, as it takes too long to move. 

Correct. The BCD circuit won't work on a Tortoise.  It's based on charging a capacitor and discharging through the turnout coil in a pulse that dissipates making a momentary contact.  It won't work long enough for a Tortoise.

[peteski]

Correct. The BCD circuit won't work on a Tortoise.  It's based on charging a capacitor and discharging through the turnout coil in a pulse that dissipates making a momentary contact.  It won't work long enough for a Tortoise.

That sounds like a typical capacities discharge circuit  used for many decades with twin-coil machines.  The reason for using a slowly charging capacitor which would provide instant burst of energy was to prevent coil burnout is  someone as to hold a route selecting push-button down too long.

But Kato machines, while being coil-type machines, need  polarity change to throw the points, that circuit must have been capable of flipping the polarity.

[peteski]

Another option is feeding power to both outside pins (1 and on the Tortoise through 555k resistors.  Then just ground pin 1 or 8 to move it the direction you want it to go.  We use this with a "switch key" on Modutrak so that we don't have live buttons.  The key is just a shorted out RCA plug.

555,000 ohms?!  That would not supply even fraction of current needed to run the Tortoise motor.  5.5k (5,500 ohm) might be low enough for that.

Regardless, Max seems to be interested in connecting indicator LEDs into the motor circuit.

[PennsyPride]

https://trains4africa.co.za/?p=1659
Link to several circuits for LED indicators for twin coil, Kato and stall motors

[Rivet Miscounter]

The other one that was discuss often was the super secret BCD setup for Kato Unitrack switched.  It was G. R. Stilwell that had it and you had to message him to get a PDF with the details.  He passed a number of years ago and the method became more public.

It's nothing spectacular, pretty much anyone that understands RC circuits would have figured it out.  I never understood why all the secrecy.

I think this is the same guy we're talking about here, but I think he was convinced that Kato was going to pay him big dollars for his circuit to add LED's to their turnouts.

I'll admit I'm fairly surprised that Kato hasn't put decoders into their Unitrack turnouts by now.   That was my argument to him back then (15 years ago probably?) is that Kato would probably skip right to decoders that may or may not have features like LED's, Local pushbutton controls, etc.

[peteski]

I think this is the same guy we're talking about here, but I think he was convinced that Kato was going to pay him big dollars for his circuit to add LED's to their turnouts.

I'll admit I'm fairly surprised that Kato hasn't put decoders into their Unitrack turnouts by now.   That was my argument to him back then (15 years ago probably?) is that Kato would probably skip right to decoders that may or may not have features like LED's, Local pushbutton controls, etc.

Well, Kato in general does not seem to be really a front-runner when it comes to factory-installed decoders in their locos.  The made some models decoder-friendly, but the locally installed (by Kato USA) decoders in some of their offerings to me do not count as true factory equipped models).  I don't think they do that for any of their Japanese prototype models (which after all are their bread and butter).

I am also now recalling that Atlas forum member with the super-secret LED indicator circuit For Kato turnouts. I remember I engaged in a bit of a guessing game with him. But I also seem to recall that the circuit was only for indicating the route of the turnout, not actually throwing the switch.

[Sokramiketes]

555,000 ohms?!  That would not supply even fraction of current needed to run the Tortoise motor.  5.5k (5,500 ohm) might be low enough for that.

Regardless, Max seems to be interested in connecting indicator LEDs into the motor circuit.

Sorry, I fixed it.  I remembered red/red/red on the color bands but not the right value calculation!  2.2K is more better. 

[peteski]

Sorry, I fixed it.  I remembered red/red/red on the color bands but not the right value calculation!  2.2K is more better.

Yes, that makes sense!
Your example does not use he Tortoise as stall switch machine, since the power is removed from the motor at the end of the throw, but the chances of the gear train moving out of the end position are very very low.

[mmagliaro]

Stillwell!  BCD!  THAT'S IT!
No, I am not especially interested in the LED indication.  What I remembered was that it could be a way to kick a
LATCHING relay one way or the other with a toggle switch, but not have to keep the latching coil energized permanently
after flipping it.  i.e. You flip it, the current pulse fires the latching relay, the capacitor charges up, the current shuts off,
and you are done.  Flip the toggle the other way, the same thing happens.

Okay.. who has the Stillwell circuit info??? That's what I'm looking for.

[peteski]

Stillwell!  BCD!  THAT'S IT!
No, I am not especially interested in the LED indication.

Oh, ok.  Glad you found it.  The subject line of this thread seemed to imply that you were interested in LEDs as inidicators.

[Sokramiketes]

Stillwell!  BCD!  THAT'S IT!
No, I am not especially interested in the LED indication.  What I remembered was that it could be a way to kick a
LATCHING relay one way or the other with a toggle switch, but not have to keep the latching coil energized permanently
after flipping it.  i.e. You flip it, the current pulse fires the latching relay, the capacitor charges up, the current shuts off,
and you are done.  Flip the toggle the other way, the same thing happens.

Okay.. who has the Stillwell circuit info??? That's what I'm looking for.

But in this case it latches because of the permanent magnets in the Kato turnouts, right?  It's not related to energizing a coil per se.