Voltage dropping Resistor?

[dmgdesigns]

I need a little resistor help please. I have a 60V power supply and need to choose voltage dropping resistors for the fans in the controller box. I have searched the net for examples and this seems to be common. Would someone check these values and let me know if I am on the right path? It just does not seem right to me.

See the picture below.

F2 and F3 are 24V .09A fans.
F1 is a 12V .6A fan.

F1 = V 24, I .09
F2 = V 24, I .09
F1 = V 12, I .6

R1 = V 12, I.078, R 154 Watts 1
R2 = V 12, I .678, R 18 Watts 8
R3 = V 36, I .858, R 42 Watts 30

Thanks for your help.

[Al_The_Man]

Are you sure you do not have 12v & 24v anywhere else (PC etc) that can feed these fans from?
If not what you could do is eliminate R3 & R1, connect all fans in series with the two 24v fans in series across R2, make R2 a 95 ohm 50watt and also for safety connect a 48 or 50v zener across R2. Unfortunately it is a wastfull circuit as the fans are attempting to cool and you are producing wasted heat with the resistors.
Al

[sendkeys]

can't he just run all 3 in series. and dont use any resistors looks like you might have lucked out.

24v+24v+12v=60v?

[Al_The_Man]

No, because of the inequality of the resistance between the 24 & 12 volt fans, this would result in almost 60 v (59.6) across the two 24v fans and the remainder across the 12v.
Al

[sendkeys]

check out http://ourworld.compuserve.com/homep..._Bowden/r2.htm
might help

hay if you want to use ac adapters i can sell you two that will work for 10 bucks. 1.5 amps each 12 and 24 volt. 1.50 shipping