On semi part CQ873

[(*steve*)]

Proving hard to find. This is a plastic TO-220 labelled

2047
(ON) CQ843

Under that is a very small circle with the letters PHIL in the top half (radially from the centre) and J1 below them (horizontal)

The device appears to behave like an NPN transistor with a gain of over 1000, with the pins EBC as viewed from the front.

Oddly there appears to be another diode junction (but with 1V drop) from emitter to collector (anode at emitter)

The BE voltage drop reads as 0.65V (which possibly rules out a darlington) and BC is about 0.4V -- maybe I should repeat those at a higher current...

edit: You know, it could be something like this, as the zener and resistor could appear like a forward biased diode with a high forward voltage, but the BE voltage would be higher... (0.667V at about 2mA)

 

[coiley]

Could you attach a picture?

 

[(*steve*)]

Sure!

These aren't the best, but hopefully you can see what I'm talking about.

Here is the device (take my word for it, it's a plastic TO-220):

And here is the part number (it's 843 like I say in the text, not 873 as I say in the title):

Finally, here are the moulded in letters (not as clear as they could be, I make it PHIL J1):

Any help to you?