fascinating - is there anything in particular I should look for in a power transistor, do you have one in mind that you would rec, aiming for 40 watts preferrably? (well maybe that is a bit more than i need
Is there anything else I need to add to the circuit or that I'm likely to overlook? or perhaps a site with advice on learning to use discretes? NpN vs PNP vs Darlington array?
Is it as simple a circuit as controller voltage to Base, +12V to Emitter and Collector to fan V+?
Above, when you mentioned that the base voltage must be about 0.8 V higher than the output to the fans voltage, what spec is that (so I can compare power transistors)? Is this Base-emitter saturation or On voltage? What dose the collector - emitter saturation voltage mean? So bottom line, looking for example at the 2n4921 with a Vc-e sat = 0.6V and a Vb-e on and saturation voltage of 1.3V and +12VDC at base and emitter, what voltage can I expect to see at the collector?
Sigh, one more idea - what about the low dropout voltage regulators, expensive but specs look interesting - any experience with them?
(I'm sorry for all the noob questions but looking at the array of stuff on the net and these pratical points seem to be left out or burried in mud)