PWM with 555 help

shortbus= · Oct 7, 2011

audioguru said:
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 · Oct 7, 2011

shortbus= said:
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 · Oct 7, 2011

The schematic about the potentiometer is correct?

ericgibbs · Oct 8, 2011

J_Nichols said:
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.

PWM with 555 help

shortbus=

Well-Known Member

audioguru

Well-Known Member

J_Nichols

Member

Attachments

ericgibbs

Well-Known Member

Similar threads

PWM with 555 help

shortbus=

Well-Known Member

audioguru

Well-Known Member

J_Nichols

Member

Attachments

ericgibbs

Well-Known Member

Similar threads

Privacy & Transparency

Privacy & Transparency