Circuit for a low voltage dc motor PWM?

[Orph]

Hi,

I'm pretty new to electronics, and I need some help with a small project. Hopefully someone here can help?

I need to control the speed of 5 small, 5 volt dc motors wired in parallel. I've been told that a PWM circuit is the best and most effective way to do this. Reading up on 555 IC based circuits, I believe that they are only recommended for 5 - 12v applications(?)
Can someone confirm or deny this? Or perhaps provide a simple, inexpensive alternative circuit that will suit using a variable resistor to control speed?

 

[MikeMl]

Do you need to control the speed of each motor relative to another? It is unlikely that five motors wired in parallel will all run at the same speed.

Is you speed control open-loop, like pushing on the accelerator of a car? Or does it need to be closed-loop (with feedback) like a car's cruise control?

 

[Orph]

Thanks for replying Mike.
It's not critical for each individual motor to run at the same speed as the others, and speed control should be open-loop.
I forgot to mention that they will be fed by 3 X AA batteries in series, which is why I'm unsure about using the NE555 IC.
Something like this would be perfect I guess, if it'll work with the intended motors and power supply: **broken link removed**

 

[MikeMl]

Your link didn't work, but I have built that 555 circuit before (the one with the steering diodes in the timing network). You could use the CMOS version of the 555 to make the circuit work down to 3V, or build this one.