Reducing speed of AC axial cooling fan

One resistor is 1K, two in series = 2K, 2 in parallel = 500 ohms. One of those ought to work. So buy a few 1K, 10 watt resistors. If they get hot, you can always fan cool them.

John

Agent won't wrap an outgoing line that begins with a space, like this one, although the receiving newsreader may not respect that.

John

hi guys, i think ac motors, are controled using inverters and may be cycloconverters, some thing the change the 60 HZ of the supply to 40 or

30 HZ, will control the fan speed inverters are the right solution for speed control Sherif

Hi John, hi Phil,

Final outcome, about 1470ohms for a fast and relatively queit throughput. Picked up some cheapies from Maplin yesterday, some 3W resistors to get the values right. They do get VERY hot, as to be expected but was never intending to use them, just getting the values roughly right. Space is at a minimum so on Tuesday I'll pickup a 1K and 470 in 50W from Rapid then wire both fans in parallel through the single pair of resistors. Really just going to go overkill so that I don't have to worry about what they're doing.