PWM circuit - calculating capacity and resistance

[Drake122]

Hey guys!

I was trying to make a PWM circuit, but don't really know how to calcaulate the discharge cap and the pot to use to be able to maximize its "bandwith". This test circuit I made in EveryCircuit only regulates the amps between 27.9 and 30. How can I make as close to 0 and 30 as it can get?

[danadak]

Some questions -

1) What is the bandwidth of the oscilloscope you are using ?

2) You mention amps, what does total circuit schematic look like ?

3) You referred to BW, normally a PWM is low pass filtered into DC. If you need
it I have an ap note on calculating filter values which control ripple and settling
time in the DC output.

Another approach -

http://www.instructables.com/id/Yet-Another-Simple-Pot-controlled-555-PWM-generato/



Regards, Dana.

[Drake122]

Thanks, but its just a test I'm trying to learn electronics, so for now, I just want to make that circuit, which I made in EveryCircuit work. Posted a screenshot. I'm not able to lower the amps on that lamp.