8 Apr
2012
8 Apr
'12
10:15 a.m.
On Apr 8, 2012, at 12:44, "Rob Jarratt" <robert.jarratt at ntlworld.com>
wrote:
I have breadboarded the circuit above and tested the 4 Darlington
Transistors. The one that was showing slightly different values to the rest
with my diode test turned out to switch on the bulb regardless of whether
the resistor was there or not. The others worked as they should. So I will
now look to source a replacement.
AFAIK, TIP125s are still pretty common (at least in America). I have a bunch in my
toolbox. Presumably there is a good European equivalent that is easily sourced in the UK
(much like there are easy European equivalents to 2N3904/3906, etc). Just look for pretty
generic power Darlingtons and narrow your search down from there with the Hfe and Ic
parameters (and perhaps cutoff frequency).
- Dave