> to offer any help.  I have a circuit where I am feeding -24V
> into a 7905 linear regulator.  It gets very hot, can't keep
> your finger on it.  It is on a pretty hefty heatsink.  I took the
> output leg loose and measured the current draw its supplying
> and it shows to be 280ma

i/p limit for a 7905 is -35V, so you're OK there, but the power
dissipation in that 7905 is over 5W. You'd be better to drop a
lot of the voltage (16V) through a resistor. Off the top of my head
it looks like 56R 10W to give you 8V at the 7905

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