Protection for driver boards

I was talking about a PTC, PolySwitch Resettable Device.  They come in all different ratings, so you can tailor the device to the job at hand.

I don't think any circuit protection can totally protect you from shorting stuff on the board, many times there are low level signals that wouldn't affect a fuse.  A PTC is also not nearly as fast as a fast blowing glass fuse, it's a thermal device.

I use them in stuff like motor leads for the ERR Cruise Commander Lite to protect against motor stalls.  I learned that with my first install of a beta CC-Lite installation.  The locomotive hung up on a switch and took out the drivers before I realized what happened.  I also use them in passenger cars between the rollers, in a derailment if the roller is on the outside track, the PTC opens before the wiring melts.  Same reason I use them when I share power between a steam locomotive and the tender, a PTC protects the tether wiring.

hi john can you list the devices you are talking about by part number and where to purchase? for instance mouser electronics , Digi key electronics etc etc.? and TVS diodes for engine protection and module protection and possible fuse that are a one time blowing, solder in circuit!

thanks john

Alan

Here's a bunch...

http://www.bourns.com/docs/Product-Datasheets/mfr.pdf

I was wondering what current values were used for single motors, two motors, tether, etc.

I use a .9A hold one for many motors.  It doesn't trip until around 1.5A, and it's very rare that you'll draw that kind of power with a small locomotive or powered unit.  For the tethers, I use a 1.1A or 1.6A hold one, dependent on the size.  Since the tether one is only called on to deliver current occasionally, it's doubtful it'll trip, even if it's overloaded briefly.  For passenger cars, since I'm almost always in there putting in LED lighting, I use a .21A hold one, they'll never see that much current anyway.  I bought an assortment of them from the .21A ones to some that are 6A trip for track power districts.

Here's a small list of PTC's & TVS with part numbers. Several were contributed by GRJ and all were from other forum members. If anyone has any more to add please let me know.