Does anybody out there that changed to DCC have any 3 section 25 ohm taper wound rheostats or know where I can get some. MRC used them in there older power packs
Is there an exact unit that needs this. I have bunches of old DC power packs but I don’t know if they have a 25 ohm without measuring them. Is there some requirement on the rotation - 330 degrees?
There are bunchs of electronics supply houses out there:
http://www.fistells.com
http://www.farnsworthelectronics.com/rheostats.htm
You sure you need taper-wound rheostats? Typically something with that description would be for audio purposes. Best place to start might be local electronics suppliers.
MRC power packs used taper-wound rheostats for better control range. The Marnold ones were too. As was what seems to have been the most popular one used back in the day, the Ohmite. Being taper-wound let yo get more voltage per degree of motion in the early steps to reduce the dead space in the throttle before the loco started moving, then at the upper end the control was much finer.
–Randy
Are you sure you want 25 ohm? If this is for locomotive control, 25 ohms is generally too small unless all your motors draw 0.4 amps or more running light. Typical MRC HO power packs used 40-50 ohm pots for reasonable slow speed control on light current draws. The Marnold lever rheostats could be had in 25 ohm, but again, that was intended for the O gauge guys.
Fred W