Need a circuit for a simple square wave generator with the least amount of onboard components, also need a current monitor..

Try an application based on the 555 timer for your square wave generator. Simple and minimal components.

Cheers, Alan

sorry I should've meant "duty cycle control" when I said "pulse width control"

the frequency I need to generate is from 10kHz to 20kHz so I hope it's a simple circuit, thanks again!

And the voltage output and current demand doesn't really matter as I can use transformers and transistors/MOSFETs to drive the output, so basically I just want the most simpliest generator, thank you!

"Bill T"

For operation at 10 kHz, change the pot ( VR1 ) to 10 kohms and C1 to 10 nF ( 0.01uF).

.......... Phil

will this be a square wave output or sine wave output?

"Bill T"

........... Phil

Hi I just went through that page, and the circuit is a pulse width control thingy, with only 1 control - pulse width, do I need a separate circuit to generate and control the waveform? ie. another 555 circuit and somehow connect them together?

when you say sharp rectangular wave do you mean square wave or sawtooth wave?

I think I sort of understand the circuit better now, and it seems the value of C1 will affect the frequency, whereas the VR1 will affect the pulse width, but it seems the value of VR1 will affect the frequency too, but how do you work out the values to affect the output frequency? Do you just use a variable capacitor to replace C1?

"Bill T"

Just one 555 - surprisingly simple, what ?

........ Phil

"Bill T"

It works like a charm.

............ Phil

ok, something clicked and I think I got it now, since you're using half of VR1 to charge and the other half of VR1 to discharge, the whole VR1 value determines the cycle. ie the waveform's frequency, so with a fixed value VR1 & C1 will yield a rough frequency value, but if I replace C1 with a variable capacitor I will be able to fine tune the frequency value! Am I right?

so now where can I find a circuit for some "current monitor"? for eg. to monitor the electric current passing through the motor M1? Would I use some kind of op-amp or something?

It sounds like you are building a motor controller. Why not just buy one? Or get plans for a "Motor controller", instead of getting plans for each individual component of one?

Cheers, Nicholas Sherlock

How much do they cost if I buy one? Where do I find them?

It is surprising, and seems enough for what I need! Thanks!

A single chip microcontroller is the smallest component count solution

- 1 chip, no external components required except for your required current sensor. The PIC10F206 is a 6 pin SOT-23 package with internal 4MHz oscillator. No PWM module, but you could probably do it in software. The PIC12F683 is an 8 pin DIP/SO with 8MHz internal oscillator, 4 channel 10bit ADC, and a PWM module. The ADC could be used to detect the current level.

Dave :)

For a wave generator Dick Smith had a kit imported (under one of these strange names) it was cheap and on a board about 40mm by 40mm based on