Here’s one flaw with using caps on DC locomotives that I haven’t seen mentioned: The amount of power a cap can store is a function of what voltage to which you charge the cap. The cap will only charge to the track voltage. The purpose of the cap is to prevent stalls, but when do you typically have stalls? When running at low speeds, of course, which means low track voltage. Low track voltage means very little power stored in the cap, so when you need the cap the most is when it would be the least effective.
Very old question for those who missed it.
This question pops up every so often. It will not work. Reverse the power pack p[molarity and the caps blows or at least lets out a puff of steam if the power pack can provide enough current. Try it if you do not believe it.
Electrolytic caps do not like reverse polarity and again, bipolar caps are NOT storage capacitors. Electrolytic caps are.
All people have to do is Google the two different type caps for details of characteristics. Put opinions aside.
Rich
Hi Folks,
I have used this bi-polar cap
with this motor
http://www.mabuchi-motor.co.jp/cgi-bin/catalog/e_catalog.cgi?CAT_ID=fk_130rhsh
for several years now, with a couple Lionel Handcars. It is a Panasonic 3300 mfd, 16 volt bi-polar and it delivers a nice flywheel effect of about 1.5 seconds of coasting at about 9 volts.
Here it is in a trailing ore car in parallel with the motor:
and here mounted on the outside (no room inside) of a handcar painted as keg of TNT (but it hasn’t exploded).
The handcar with the side-mounted bi-polar capacitor runs on DC only (removed the bridge rectifer for forward and reverse travel), about 7-9 volts DC. The one with the trailing ore car has a Lionel reversing board that works with AC or DC.
Here is a video of the handcar with the side-mounted bi-polar cap in action:
The capacitor keeps the handcar moving over switches, crossovers, badly worn tinplate, even a dirty film. It does work!
Take care, Joe.
James: If diodes ar added to that DC capacitor circutry, the capy would only discharge to the motor, perhaps a circuit with 2 capacitors in reverse with the diodes might offer a better solution for the discharge. Once the track power is lost, the diode prevents the cap’s discharge from going backwards? If another diode then went to the motor lead, the cap discharge would go to the motor, with the diode preventing the reverse current goiing backwards. The track power flows through both of the diodes to the motor while also charging the capacitor.
I have installed a simple keep alive" electronic circuit in many of my DC powered diesels. I use a capacitor bank totally 2000 uF and a few diodes. The package fits inside an F-7 shell easily but requires some thought to fit inside GP & SD units. The 2000uF capacitor offers a 3 second keep alive when going over dirty trackage, crossing and insulated switch frogs. A 2000 uF capacitor at 25 working volts is the smallest I found. I also use a pair of 1000uF capacitors in parallel in the GP units. The Miniatronics small LED headlight requires a 470 ohm resistor. It is not hard to install.