do floppy drives need a switching p/s?

Bryan K. Blackburn oldcomp at cox.net
Fri Feb 17 15:25:11 CST 2006


Basically:

1.67 Amps X 24 Volts = 40 Watts. (I*E=P)
40 Watts - 18 Watts = 22 Watts of remaining capacity.

You need 5 Volts at 5 Watts, which is the same as 5 Volts at 1 Amp. A 
series pass regulator delivering 5 Volts at 1 Amp from a 24 volt source 
will waste 19 Watts of heat. (24V - 5V = 19V; 19V X 1 Amp = 19 Watts)

19 Watts + 5 Watts = 24 Watts required. Not Quite enough!

Your rated power requirements may be absolute maximums. Your drive may 
actually use less than rated, so it *could* work, but a separate supply 
would be best.

-Bryan


Chris M wrote:
> I'm guessing so. Am wondering if the 1.67 amp 24 vdc
> regulated wall warts from BGMicro are sufficient to
> power an 8" floppy drive (NEC FD1165-A). Needs 24 vdc
> @ 18 watts. Would love to devise a circuit to get the
> 5 vdc (@ 5 watts) off the same brick, but that may be
> asking too much ;).



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