PWM with 555 help

[shortbus=]

But an LM393 dual comparator has a minimum output current of only 6mA

A 393 or 339 comparator only sinks current. It doesn't source current, it needs a pull-up resistor for that.

 

[audioguru]

A 393 or 339 comparator only sinks current. It doesn't source current, it needs a pull-up resistor for that.

R3 is the pullup resistor for the output of the comparator. R3 also supplies base current for the output transistor.

 

[J_Nichols]

The schematic about the potentiometer is correct?

 

[ericgibbs]

The schematic about the potentiometer is correct?

hi,
When you turn the pot clockwise, the voltage on wiper 'B' will increase.

If you want the voltage to decrease on wiper 'B', as you turn the pot clockwise, swap 'A and C' over.. OK.