Lionel O27 switch modification

The DZ1000 uses a small microswitch to cut off motor current at end of travel, full point closure.  Thus this circuit would not be of value here, other than might give more zip to motor throw power insuring end to end lock (speculation).

I believe (use this info at your risk, maybe try on salvaged motor) that you could use this capacitor discharge circuit for Atlas motors,  The two outside motor screws would connect to the control rails, assuming that rails are actually insulated from outside rail ground (might need to ohm-meter out those rails and cut jumper as needed to maintain all outside rail continuities.  The  wire you show as "jumper wire" would go to the switch motor center screw (which should be the common connection between both coils.)  You may have to adjust the resistor for how fast the capacitor recharges after each use.  The capacitor supplies the high current to get motor to move but then dies away so coils aren't being operated at full voltage and over heat.  Suggest start with high value resistor then decrease until you get motor to just snap reliably but not overheat (measure coil voltage after operating, ie a car sitting on control rail or holding down the remote control switch).  Higher the value the longer it takes capacitor to fully recharge but lower voltage across coil. 

Of course you can still connect your remote control box wires to the two outside motor screws and its common third wire to outside rail ground.

Hope this helps. 

Thank you I wasn't sure if the DZ-1000's were protected when parking on the switch. As far as the atlas switch machines go I have about a dozen but I wasn't sure if I wanted to use them. I will probably stick with my lionel,  gargraves and ross switches with the dz-1000's and just modify the lionel switches and offer up the atlas switches for sale.

Thanks again for the info 

Gary

A capacitor discharge circuit is the only safe way I know to power Atlas switches. Without a stuck switch controller will fry the Atlas Switch Machine.

Correct me if needed.  Atlas does make a special board that I believe achieves this. I think this is it. non-derail-circuit-board.aspx

Forest

I have seen some discussion on the atlas circuit board but they are very hard to find. I don't have any atlas switches but I do have at least a dozen atlas switch machines I may just put them up for sale and stick with the DZ-1000's and my lionel switches.

Gary

If the purpose of the Capacitor Discharge method is to deal with the "stuck switch" burn-out scenario, how about 25-cent PTC resettable thermal fuse?

I am not sure of the reset time of the fuse. I am looking for someway to keep from burning out my lionel switches when a train is parked on the switch for awhile yet still operate in a non derail shortly after the parked train is moved if that is possible. I have read about the capacitor discharge circuits being a more common method. it also looks fairly simple

I am thinking of using 2-100 ohm resistors in series with a 4700mfd  50v capacitor but I am not sure what diode to use. Any suggestions greatly appreciated.

Gary

A good diode and dirt cheap is any in the  1N4001 to 1N4008 series.  Only difference is voltage rating so 4001 is a 50V type which is more than adequate.

stan2004 posted:

If the purpose of the Capacitor Discharge method is to deal with the "stuck switch" burn-out scenario, how about 25-cent PTC resettable thermal fuse?

The fuse will keep trying to reset and firing the switch. It may not even trip until the switch machine is toast.  The capacitor discharge system will not allow the capacitor to recharge as long as the button is stuck. Until recharged no power goes out to the switch.

Forest posted:

stan2004 posted:

If the purpose of the Capacitor Discharge method is to deal with the "stuck switch" burn-out scenario, how about 25-cent PTC resettable thermal fuse?

The fuse will keep trying to reset and firing the switch. It may not even trip until the switch machine is toast...

Once the PTC trips, it still passes a small "trickle" current which keeps it warm so to speak and hence remains in the tripped condition.  You must remove the short/fault which then allows the fuse to cool down and reset.  So it should not "keep trying to reset" as long as the short/fault persists.   It is true that you must choose a suitable PTC value - which allows you to select a nominal trip time of, say, 5 seconds in response to a short/fault.

Forest posted:

...

The capacitor discharge system will not allow the capacitor to recharge as long as the button is stuck. Until recharged no power goes out to the switch.

If the short/fault persists, a small current (probably on par with the post-trip warming current in the PTC method) still flows thru the diode and 47-100 Ohm resistor.  The capacitor will charge to less 1V or so and some negligible power will still flow into the switch.   Perhaps all explained in the capacitor discharge documentation, but if you go for a fast recharge time (lower resistor value), you need to mind the power rating of the resistor when in the short/fault condition.  I don't think, say, a 1/4 Watt resistor will be suitable.

My plan is to make the discharge circuit with 2 100ohm 10w resistors, a  4700mfd 50v capacitor but I'm still not sure of the diode. The 1N4001-1N4008  series only comes in 1 amp rating will that be enough. I was looking at 1N5403 because it comes with 50v, 3amp rating. 

 As far as electronics goes I can soldier and connect wires but circuit design is way above me.

I also would like to thank you all for the information this forum is a wealth of information  again thank you

Gary

1 Amp is enough. A simple calculation using "Ohm's Law" or Voltage = Current x Resistance.  So if you have 16V Accessory voltage, and 100 Ohm resistor, your worst-case sustained current = 16V / 100 Ohms = 0.16 Amps which is well less than 1 Amp.  It's actually less than that since you are only use "half" of the AC voltage - you're good to go.

If you have a choice, I suggest the 1N4003.  They will be the same price (a couple pennies each on eBay).  The 1N4001 is fine for this application but the OGR gang routinely suggests the 1N4003 which has been good for every OGR discussion I've seen to date.  So if you're only going to "stock" one diode, get the 1N4003.  Just a suggestion...