7356Re: NSLU2 using 7805s and a 12V battery
- May 6 9:58 PMI just remembered a design trick for boosting a regulator: one
circuit I've seen used a PNP power transistor with the base
connected to the INPUT of the regulator (with a bypass resistor,
probably 22ohms). By putting the junction on the input side the
output regulation isn't compromised by Vbe drop.
--- In email@example.com, "efilvasers" <efilvasers@...>
> First off, I'd like to thank you all again for your help.
> I should have done a bit more research before jumping head first
> this project.thermal
> Next time around, I'm definitely going with a switching regulator.
> My quick solution is this:
> A 2N3055, bolted to an old CPU heatsink (which still had some
> compound on it), with the base connected to a 7805 (with a smallheat
> sink), collector to the battery, and emitter to the NSLU2 (andother
> Also, the ground pin of the 7805 is connected to the real ground
> through a 1A diode; when I measured the emitter voltage without
> it read about 4.4 volts, went up to about 5.2 after adding it (runsthe
> about 4.9 with the NSLU2 on).
> The 7805 heatsink doesn't even warm up, while the 2N3055 heatsink
> warms up after a couple of minutes, but went back down to near room
> temperature when I placed an extra 80mm fan next to it.
> I'm using the same solution for the 9 volt regulator (both sharing
> same fan).
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