Re: Circuit for 12V lights to come on each evening.

 



FET!

get

Easy enough for the circuit to check the state first in any case.



You know of a mosfet with no losses at all, or you think the relay will
consume more in a few milliseconds than the mosfet will in a few hours?

MrT.

 


hmm it seems they cost about 100nA (ballpark) to run.
that adds up quickly.

 



Since when is "100nA" a "power" loss? Seems you still fail to consider the
FET's on resistance and actual load current.
If it works for you, then I sure don't care  But your claim that "a latching
relay would use less *power* than a mosfet driven by a nor-nor cmos
bistable." is still a little shaky IMO though.

MrT.

 


have a look at some figures:

OMRON - G6BK-1114P-1-US-DC12      : 30 milliohms

FAIRCHILD SEMICONDUCTOR - FDU8580 : 9 milliohms

also, the relay costs twenty times the price of the mosfet, and can
only handle half the current.


What lets the mosfet down is the gate leakage when on and the D-S leakage when
off.

I think there's more power to be lost in choosing an inefficient dark detector
and/or timer circuit.