I'm experimenting with the Kadee #708 electromagnetic uncoupler for my N-Trak yard modules. I want to have a timed delay switch that when activated provides power to the uncoupler for a specified length of time (so I don't burn out the electromagnet). I also wanted to adjust the timer to uncouple the cars and allow the couplers to stay open to back up the car to be spotted. I looked on line and found various 12volt timer relays and found an example (see attached photo). They list out anywhere from $5 to $15. Has anyone tried run an electromagnetic uncoupler this way? Any electronic "Gurus" care to offer advice? Thom
I wonder what the amp draw of the Kadee uncoupler is and if the solid state timer is up to the task? I'm not sure what the blue component is on the circuit board, but if its specifications indicate its ability to shoulder current (and not its input current), it's certainly up to the task. I'd imagine the uncoupler's draw would be puny, perhaps 1 Amp at most? I'm not a skilled electrical guy, but do enjoy tinkering around with circuits and this sort of thing.
Hardcoaler The specs for the Kadee #708 electromagnetic uncoupler are 8-12v DC and 3 amps. The specs for the Kadee #309 electromagnetic uncoupler are 16v DC and at least 3 amps. The sample relay switch and others on line are rated from 5 amps to 10 amps. DCSharkman I'm can use either the Kadee #708 or #309 electromagnetic uncoupler. See links: https://kadee.com/htmbord/page708.htm https://kadee.com/htmbord/page309.htm
Ooo -- I really underestimated the current draw. But, no sweat it seems -- those timers are beefy. I think you have a really cool idea here.
I have the Kadee electromagnetic uncouplers on my N scale layout. I used a timer similar that had a relay rated at 10 amps. A time of around 10 seconds worked well when I automated them with a digitrax DS-64 switch activator and controlled by a script in JMRI.
I used that timer board to control the #708's on my N scale layout. I have 8 of them operating with a 10 sec delay triggered by a momentary pushbutton. However, you need to add a diode to the wiring to avoid damage to the board relay. When the 10 sec is up, the power to the magnet is removed and that causes a power surge to bounce back toward the relay. Eventually, this will damage the switch in the relay. Probably a poor description but the net effect is to damage the switch. I don't have the details handy but I can dig them up and post them if desired. I also included a LED in mine so I can tell when the power is on at the magnet. As a side note, if I had to do it all over, I would probably not use the #708 in my layout. I seldom use them plus they are difficult to install without damage to the top piece between the tracks plus alignment is critical to avoid problem with the wheels when they roll over the magnet. I would recommend that you trim the edges of the arrow head shaped ends down to the same width as the rest of that top piece. Will not hurt anything and will avoid the alignment issues. Also, if you buy any more #708, be sure to get current production versions. The older units (brown center piece) break real easy. I had to buy extras just for parts.
Take a look at the railcrew uncoupler from rapido. https://www.rapidotrains.com/on-off-remote-coupler/ I have been playing with this unit for a little while and it works ok for n scale if you lower it about a 1/4 inch or so. It can be installed after the track is already down and it only draws current momentarily.
Michael, Does this unit have any part showing in or above the ties like the Kadee unit does. That is my gripe against the Kadee. The portion above the ties is difficult to get into a position that does not interfere with the car wheels. In my case, I have mine mounted in Kato N scale Unitrack. That requires me to cut a hefty slot in the ties/roadbed between the rails and then try to attach it so that it is properly centered and the height does not interfere with car wheels or the uncoupling pin. Can be done but it is a pain. Why do you recommend lowering it 1/4" for N scale? !/4" from where (bottom of tie?) If the Rapido unit is completely below the ties yet still uncouples reliably, I would be interested in trying one out. Paul D
Paul There is nothing above the track. There is only a small hole that a blue led shines through and reflects on the trip pins, so you can tell when the couplers are in the right position. My test track that I have been working with is mounted on foam with no roadbed yet . The magnets are so strong, that when the unit is flush against the bottom of the ties it holds my small switcher in place. I made some spacers out of card stock and started to lower the unit, until it worked properly. With the Unitrack you may not have to lower it at all. Give it a shot. Retail was less than $20 at my local hobby shop.
The rapido is very clever that it uses permanent magnets rotated up into position rather than an electromagnet.
