On 08/07/2013 10:07 AM, Cydrome Leader wrote:
Roger Blake wrote:
On 2013-08-07, Cydrome Leader wrote:
How large are the batteries you're charging?

12 volt lead-acid car batteries, I should have mentioned that if I didn't!

What parts are on that board you have now? Can you post a photo?

It does look like they cheaped out on a couple of rectifiers, hence
the 28V center-tapped transformer. (The transformer looks surprisingly
hefty, though.) But then again there are 2 SCRs on heatsinks and it's
surprising how many discreet transistors this thing has, enough to make
a decent transistor radio, but who knows how many are real. A bunch
of what are probably phony 1% resistors completes the components. No
ICs. No capacitors. The center tap of the transformer feeds into the
center section of the board through a circuit breaker. Each side of the
secondary then feeds into its own symmetrical section of the board.

I tried taking a picture but my camera does lousy closeups, will have
to borrow one...

Are these "SCRs" really SCRs or just large power transistors? Did the
thing sing or make horrible PWM sounds when it worked?

I have seen real SCRs in telecom rectifiers (giant battery chargers/power
supplies).


Physicists tell me that SCRs will work as transistors.