O Gauge Toby Help!

     I think Lionel round base accessories have a voltage limiter that keeps the power to the motor from exceeding 6 volts DC no matter what the input voltage is. I not sure what would be involved in adapting one of these (at the least, you would need diodes to drop the voltage by 1.5 volts) or building something like it. gunrunnerjohn or another will probably know.

     You could use a whistle relay for Toby-talk, then, using a layout-side button hooked to a rectifier, visitors could trigger the talk.

     For chuff, regularly spaced magnets is the easiest solution I can think of. Anything else would be unduly complicated for an engine that will only operate on one layout.

Hope this helps,

I'd probably use a small magnet on a driving wheel and a reed switch to simulate the microswitch you used to have.  Having multiple chuffs/rev is a non issue with a novelty engine like this one, you just want it to chuff.

For the power, you can do it with a few components.  A couple of 1N4003 diodes, 330uf 35V capacitor, and an LM7805 regulator.  You can power it directly from track power with these components.

The second diode is to put on the output of the regulator to drop it from 5V to around 4.5V.

If you don't want a push button for the talk, your idea of another reed switch and randomly placed magnets sounds good.

You will want to slow him down a bunch, or the talk will get lost.  I'm sure with three coin batteries, the volume isn't all that great, so track noise will drown out what he's saying.

Rich, I was thinking more along these lines.  You don't need a bridge for the low power you're considering, and you missed the extra diode to drop the 5V to 4.5V.  You could also use an LM317 to generate the 4.5V, but that requires two resistors, so I figured we might as well save a component.  The .1uf cap is optional, it's typically used to prevent any oscillation of the regulator with certain load circuit configurations.

GRJ,

    What is the purpose of the inductor in the upper left?

EDIT: I just realized that it is probably for suppressing noise, right?

Thanks,

Unless you can get parts locally I would use Digi-Key for small orders (and large too). Their pricing is good and shipping is very reasonable. I started using them on a recommendation from GRJ and have been very happy with them. About the only place I get things now.

The choke is for DCS compatibility.  If you have a supply that uses a filter cap, it can frequently affect the DCS 3.27mhz signal, so I include a choke in any design I do now.

Rich, Digikey or Mouser are my top places to buy parts.  If you're only building one, I could put a "kit" together for you and make it a bit easier for you.

John, That woud be fabulous!  Thank you.

Please me know how you want payment.

Rich

Drop me an email Rich.