On 1/5/2017 1:04 PM, Jeff Liebermann wrote:
....
DLG600 is rated at 90V/25A, while the TIP32C at 100V/3A. That would
seem to be a rather poor choice for a substitute.

What you don't know, cause I didn't say, is that the supply is 50v, 1.5A.


If you substitute silicon, you'll need to change some component values
to deal with the Vbe change from 0.3v to 0.6v. Probably doubling the
resistance of the 8.2 ohm sense resistor, and changing D7 from
germanium to silicon. Hopefully, the current ranges will remain the
same. The silicon device will have a better gain-bandwidth product,
so a few ferrite beads to keep the power xsistor from oscillating. If
you choose to use a different package, you'll need to do some creative
mounting and heat sinking. The analog series current limiting
transistor will dissipate considerable heat at high loads.

There is no calibration in the circuit - the current limit is picked by
rotating a pot until the current is limited where you want it.
Hopefully this will be able to account for the different device. There
was a poster who did this, so I'm probably OK.

I will mount it, isolated, to the steel frame. And at 1.5A that
"should" be enough sinking.

Sounds like too much work. I'll see if can find one in my junk pile.
I've been hoarding germanium devices for years for use in repairs.


My order is in, but thanks anyhow.

Bob