Hey Guys, I just visited eBay and noticed they had a lot of old MRC DC power packs for sale. A lot of these older power packs had a switch for what was called "Pulse Power" which as I remember was a modified non-rectified DC current which was used to simulate slow starts and stops. The problem with these power packs are that in pulse mode the DC waveform is intermittent and the voltage peaks are chopped which causes the DC to act more like an AC current. This causes the commuters and brushes in the motor to overheat and burns up the motor. So, word of warning, DO NOT USE PULSE POWER! That probably accounts for all the listings on eBay of these older power packs. BEWARE! George
I've heard the same about the overheating motor issue however my old Troller Autopulse Momentum 2.5 gave me 20 years of good service without any troubles but that was with light use. The increase in DCC use could account for some of those DC units showing up.
In order to get DC from the old power packs it has to be rectified. Most MRC power supplies are not filtered at all giving you 120 HZ full wave pulsed DC. What they called pulsed DC was actually half wave rectified DC, in other words 60 HZ pulsed DC. In both cases, this was done (unfiltered DC) to run the older cheap motors, and yes it did heat them up as indicated above. Retired Electrical/Electronics Engineer.
Still running my MRC Tech-II 2400. Use the "pulse power" often, but just for starting up or slow speeds. Never had any problems, but most of my run times are relatively short vs you serious operators. Ken
Is there a difference between this pulse power and a momentum setting. Cause the club I'm in uses MRC packs that have a momentum on off switch. I can't remember what series they are. If its like this pulse power thing I'll have to bring up the subject to leave the momentum off. Ethan
Ethan - No, momentum and pulse power are two entirely different things. When momentum is on, and you decrease the throttle setting, the train continues to roll along like the prototype would and come to only a slow, gradual stop. There is also a brake to stop quicker. Pulse power is far more elementary, and only serves to make older design motors start turning easier and smoother, and to run smoother at slower speeds. I start up my older stuff on pulse, then once we get rolling smoothly, switch it off. Keith or Richard can explain it all in more detail if you have questions. Ken
Ok, I get the concept now. I just wanted to make sure that someone wasn't going to ruin an engine using it. I take my DCC system and hook it up to run my trains so I don't have to worry. Thanks Ken Ethan
