Wiring capacitors to power turnouts

[wacowally]

In the early 80's I used capacitors to power my switches when controlling multiple switches with one button. (MATRIX) I have recently finished wiring a new layout and can't remember how to wire the circuit. I used directions from PRACTICAL ELECTRONIC PROJECTS FOR MODEL RAILROADERS, Switch Machine Contols, but I find that the capacitor is not discharging when I push button. If I disconnect all wires from the capacitor and short both leads it does discharge. This system worked for me 20 years ago but can not make it work today. Any help out there?

[Anonymous]

When we used snappers or solenoid operated switches, the capacitor dumped a sharp current spike and the swiches could move together. I suspect that you are now using motor drives and the capacitor sees more reactance when you throw trhe switch. As the motors move, the capacitor recharges and you do not see it "shorted."

[BR60103]

I don't think capacitor units can be used with motor drives.
Have you checked polarity? Capacitor discharges are directional and the diode matrix is also directional; if you wire one backwards, nothing will happen.
Try wiring up a single switch machine and run the two control wires out. Hook the common to the common from the CD unit. Take the other wire from the CD unit and wrap it around one end of a diode. Touch the other end to the wires on the switch machine to see if it flips. If it doesn't, turn the diode around. This will tell you which way to hook up the diode matrix. Oh, test it without the diode first!
--David

[wacowally]

No. When I restarted I had boxes of equipment, so I am still using snap switches. Thanks, Wally

[wacowally]

I'll give it a try. I had about 40 snap switches when I unpacked everything this year so that's what I am using. Thanks, Wally

[Sperandeo]

David Brampton is right, you don't want to use a capacitor-discharge power supply with motor-drive switch motors. If you're still using solenoid switch machine, though, the C-D supply remains a good method. Circuitron and Miniatronics both sell assembled C-D circuits at reasonable prices.

So long,

Andy

Andy Sperandeo
MODEL RAILROADER Magazine

[wacowally]

Thanks for the help. Removed some resistance from the circuit and it works fine now. Started new layout after 20 years and had 35 snap switches packed away in boxes, so will stay with them for a while. Wally