I've burned out a few Atlas switch motors by having trains stop on the non-derailing switches I've built (with the aid of Dave Hikle - every time I plug him he becomes harder to get a hold of). Actually, the wiring which works as a non-derailing feature was installed so that trains wouldn't stall on 054/072 and No. 5 switches. They, if you don't know, have long dead sections of track. The feature works as it should, but if an axle stops on the activation section it can burn out the switch motor. To reduce the risk of motor burn out I only power the switches when needed. But it would be nice to have the switches on all the time. I do have red LED's that light up to warn me, but I have 5 to watch, and it doesn't take much of a delay to wreck the motor. I know Atlas has a non-derailing circuit, but it gets pricy to start doing a bunch of switches.

I understand that one can wire some capacitor(s) on the activation wire to help avoid this. Does anyone have a schematic that they can post?

Please don't bother telling me of other brands I should have used. I'm otherwisw happy with the switches.

Thanks,
Alan

http://ogaugerr.infopop.cc/eve...=799102091#799102091

See this post. Relays can be used instead of toggles for automated switching.

Dale H

This message has been edited. Last edited by: Dale H,

Dale H,
Thanks for the link. Couldn't you just do this with a slide momentary switch as well?
Alan

No, you need a toggle not a pushbutton momentary unless you used mechanical latching dual coiled relays which are expensive.

Dale H

Dale,
I sure appreciate your help on this topic. Your description of the schematic seems to be geared for multiple throws - if I'm correct. If I want to throw just one switch at a time what would be the specs of the capacitors to use?
Thanks,
Alan

quote:

Originally posted by Dale H:
No, you need a toggle not a pushbutton momentary unless you used mechanical latching dual coiled relays which are expensive.

Dale H

quote:

Originally posted by ajzend:
Dale,
I sure appreciate your help on this topic. Your description of the schematic seems to be geared for multiple throws - if I'm correct. If I want to throw just one switch at a time what would be the specs of the capacitors to use?
Thanks,
Alan

quote:

Originally posted by Dale H:
No, you need a toggle not a pushbutton momentary unless you used mechanical latching dual coiled relays which are expensive.

Dale H

2 capacitors are needed to throw one switch or pairs of switches wired in parallel.. One discharges into the machine(s) while the other one charges. 2200uf 35 volt normally will throw one machine with a 12 to 16 volt input. The capacitor charges the pulsed DC to peak voltage so 12 volts would charge to around 17 volts. On a variable volt transformer you can adjust the input so the machine works at optimal voltage. This assumes the switch machine works freely and is not binding. Atlas switches can bind if they are mounted on an uneven setting. To throw machine in pairs wired in parallel a 4700 uf capacitor usually will work.

Only the energy stored in the capacitor throws the solenoid in the switch machine and is discharged in milliseconds so there is little chance of burnout unless you really over do the capacitor or input voltage. So in practice apply enough voltage so it just works then add a couple volts. This is also good advice when hooking up most accessories. Adding a resistor in the charging circuit may reduce arcing if that is a problem but I do not use one.

The original Atlas push button can not be used since it is only single pull. As I mentioned you could use it if you had latching relays but that gets expensive.

Dale H

quote:

Originally posted by ajzend:
I've burned out a few Atlas switch motors by having trains stop on the non-derailing switches I've built (with the aid of Dave Hikle - every time I plug him he becomes harder to get a hold of). Actually, the wiring which works as a non-derailing feature was installed so that trains wouldn't stall on 054/072 and No. 5 switches. They, if you don't know, have long dead sections of track. The feature works as it should, but if an axle stops on the activation section it can burn out the switch motor. To reduce the risk of motor burn out I only power the switches when needed. But it would be nice to have the switches on all the time. I do have red LED's that light up to warn me, but I have 5 to watch, and it doesn't take much of a delay to wreck the motor. I know Atlas has a non-derailing circuit, but it gets pricy to start doing a bunch of switches.

I understand that one can wire some capacitor(s) on the activation wire to help avoid this. Does anyone have a schematic that they can post?

Please don't bother telling me of other brands I should have used. I'm otherwisw happy with the switches.

Thanks,
Alan

Circuitron makes a capacitive discharge power supply for twin coil switch machines.
It can be ordered from Walthers catalog No. 800-5303 for about $30.00. It works not unlike a toilet. Initially a large current flow to throw the switch, then a trickle current which is not enough to harm the switch motor coil. Recycling is fast, the only problem is it will not recharge while the circuit is closed.
The good news is you only need one for the whole layout.

Dale,

The circuit you supplied works but it does not lend itself to non-derailing operation. Might I suggest the following. Sorry but I don't as yet have the skill to post a schematic. From the Positive of your DC switching supply connect a small light bulb to the positive end of your capacitor. Connect the positive of the capacitor to the common terminal of the switch machine coils. The other side of the coils connect to your push button switches or the non-derailing rails as per normal. The negative of the DC switching power supply is connected to the common of the push buttons and the common rail. The DC supply voltage is'n too critical and can be obtained from an old transformer with a bridge rectifier just so long as the transformer is not used for anything else. Current needed is not too high as all it is doing is charging the capacitor through the light bulb. The only requirement for the light bulb is that the voltage be high enough so that it dosen't burn out at the voltage used, most train lamps will work.

When the switch is tripped the capacitor discharges through the switch coil throwing the switch. The light limits the current so the coil will not overheat if the coil continues to be energised, the light mearly lights up. Once the coil is released the capacitor recharges through the light and is ready for the next use. The whole thing can be ready for the next cycle in about a second or less. Only one powersupply is necessary but you should use one capacitor and light circuit per switch. There is no indication remotely of the switch position but there wasn't with the original atlas switch machine either.

Thank you for the information. I have seen it done that way and it works. The only reservation I have is that Atlas coils are a bit fragile so the trickle current needs to be limited. With the method I described switches could be thrown with a relay activated by the insulated rail method. This method no voltage goes to the switch machine.

Dale H