11 Apr
2012
11 Apr
'12
4:31 a.m.
On Apr 11, 2012, at 6:15 AM, Rob Jarratt wrote:
It's not universally true, but in *most* transistor circuits a higher
gain shouldn't hurt. Just looking at those specs, the PNP equivalent
to a 2N2222A should do the trick (I think it's a 2N2907A). Make sure
it's the A variant, though, because the regular one only has a 40v
Vce max.
...and, looking at what you've linked, that's exactly the part you
picked. It's probably fine.
- Dave
On 2012 Apr
11, at 1:23 AM, Rob Jarratt wrote:
Thanks for helping me decipher the spec.
I have identified some transistors with similar specs (e.g.
http://uk.rs-online.com/web/p/general-purpose-transistor/7390492/), but the
current gain hFE is higher at 100. Not sure if it is better for the hFE to
be higher or lower than the required spec. I need to replace a transistor in my H7140 PSU
for my PDP11/24. The
transistor is marked GPSA55J3 and the printset identifies it as "XA 55
PNP 500MW SI 60 50 P", it is in a TO-92 package.
The basic specs for the common Motorola MPS-A55 are, in summary:
Polarity: PNP
Power Dissipation Pd: 500 mW
Material: Si (Silicon)
C-E voltage Vceo: 60 V
Current Gain hFE: 50
Package: TO-92