DB>  seems like I could use a 20 amp relay powered by a paralel tap
DB> on the panel that would only draw (thru a 200 ohm coil) 60ma
DB> or less than one watt, and diddly for heat.
DB>  Or maybe one of these new IGBT gizmos, that says it has .05
DB> volt across it, and diddly for the drive on the gate.
RS>  Why not use a MOSFET ?
DB>  I thought the IGBT had less power loss.  The gate drive is so
DB> low that a separate Si solar chip could power it?
 I'm not positive; but, I think that the FET will have
a lower on resistance than the Bi-Polar.
RS>  How are you going to determine the time to switch ON or OFF?
RS> Normally, that would be done by sensing a voltage drop.
DB> no light on the Si detector.
 Good idea. I hadn't thought of a second cell.
RS>  This is why I suggested a Schottky diode. IR has one that's
RS> rated at 9 Amps and .25 VF. They also have one that's
RS> rated at 19 Amps and .32 VF.
DB>  .25 do look pretty good. how much do they cost?
 $3.81 if bought one at a time from Digi-Key. The 19 Amp
ones are $3.29 (.32 VF). (First quantity break is at 10.)
 TTYL.
 Robert
 * SLMR 2.1a * Gun control is not about guns. It's about control.
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