General Stuff(tm)

[stephen_usher]

Well, I drilled out the pop rivets and...

IMG_2823.jpg

Very definitely 19050s/60s technology. The large wound device behind the controllers is a resistor and it looks like it's insulated using ASBESTOS! (This was bought in the early/mid 1980s, so long after asbestos was known to be a problem.)

IMG_2825.jpg

Still, it looks like it should be a simple task of soldering a large capacitor on the bridge rectifier board, if tricky to get the soldering iron in there.

[exxos]

Nice bit of vintage p0rn :thumbup:

[rubber_jonnie]

Wow, very nice :)

[stephen_usher]

Tried a 470uF cap (the largest I have) across the rectifier. Definitely smoothed the output but it was up to 23V. Methinks a very large cap is needed so that the peak can't fill the capacitor.

[stephen_usher]

Thinking through this in the middle of the night, I think the best way forward for this would be:

• Put a 100 ohm resistor between the output terminals to drain the capacitor even if there's no load on the track. At 12V that should be a maximum current of 0.12A.
• Install two 15V/5W Zener diodes "face-to-face" on the outputs to clamp any output to a safe voltage for DCC chips. (The voltage shouldn't really be going above 12V anyway.)

I'd have to do this on both sides of the controller.

[exxos]

Half wave rectifier ?

[stephen_usher]

Half wave rectifier ?

Full-wave but not smoothed. It's 24V A/C full-wave rectified, so the average voltage over the whole cycle is 12V but with a peak voltage of 24V. I need to bring the voltage down to a constant 12V. (There is a half-wave rectifier mode but I'm not worried about that.)

I could either bod this on the rectifier board or on the output, but because the output can switch polarity I would need to put any electrolytic capacitors on the rectifier board.

[stephen_usher]

The 6 pin DCC adapter boards have arrived. I'm still waiting for the wires with the strange no-quite-spade-connectors on the end so as to connect the power pickup cables.

These are the connectors. I wish I knew what they were called so I could get my own.

s-l500.jpg

[exxos]

Full-wave but not smoothed. It's 24V A/C full-wave rectified, so the average voltage over the whole cycle is 12V but with a peak voltage of 24V. I need to bring the voltage down to a constant 12V. (There is a half-wave rectifier mode but I'm not worried about that.)

I mean could you use half-wave instead ? It would reduce the peak voltages, but under load the voltage may drop a bit.

[stephen_usher]

Half wave rectification is not good for motors, it causes them to overheat.