cmos pwm ?

[synthesist]

hey !

To change the pulsewidth on a 40106 oscillator you only need to place a diode on the input of the inverter, the other end goes to a variable resistor with its wiper placed to the inverter output.

but how can one modulate the PW? Did anyone try it with a resistor yet?
or is there any other way?

[RingMad]

Using the following schematic, one can control both the mark & space / duty cycle parts of the square wave. LEDs or diodes like 1N4148 work. You can also use a 4093 NAND gate instead of the 40106 (shorting the 2 inputs together).

To modulate, I guess you could replace the pots with opto-isolators ("Vactrols") LDR/LED combination.

James.

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[PHOBoS]

hmm, using a shiftregister or divider comes to mind,. but not sure how yet.

[elmegil]

A & B could be a single dual pot with the two sides wired opposite each other as well. That would give a pretty smoothly changing transition of pulse width.

[PHOBoS]