That site is very useful. The result with those numbers is not very good, so needing something more like
Fpwm=10Khz, Fc=100Hz, or 100:1 to get low ripple.
5K and 10uF -> F3db = 3.18 Hz, which is quite low, but probably ok if all you're doing is changing slowly.
oric_dan(333):
That site is very useful. The result with those numbers is not very good, so needing something more like
Fpwm=10Khz, Fc=100Hz, or 100:1 to get low ripple.
5K and 10uF -> F3db = 3.18 Hz, which is quite low, but probably ok if all you're doing is changing slowly.
My suggestion was 100K and 1uF, giving F3db = 1.59Hz and time constant = 100ms. I guess we need to know how fast the OP needs to move the valve.
I'm confused at where the RC filter would be connected in the circuit. If I was switching a transistor with one of the pwm pins, the transistor is allowing the path to ground. Is the RC filter on the collector side or the emitter side? (thinking this is an NPN)
There is a path to ground via the capacitor, is the high freq. stuff is going this route? and that's the whole point...
No that is totally wrong.
Collector to pull up resistor to +12V.
Collector to filter resistor. Other end of resistor to capacitor to ground and also to one of the inputs of your controller.
You need two of these circuits one for each input. You also need a common ground.
I am using a 2N3904 transistor, which may not bethe correct thing to use, but maybe it is. i don't know for sure...
the way i understand this, R1 would be the current limiting resistor for Arduino. but i can seem to find what the current needs to be to operate the get the transistor to 'turn on' (yes, i sure there is a very technical term for this )
i bet i would plug the need current and something like 5v's into Ohm's law and i would get something helpful???
working through the numbers, i am going to assume a 200ma collector current, which would give me something different than an HFE of 30. but i'll use 30, since this looks to be rough numbers anyways.
200/30 = 6.67ma
so there's a bit of "double it for safety margin" to make sure the base is saturated.