Electronic low Pressure regulator

[Steve V]

Hi:
I am modifying my Garage Low Pressure Spray Painter. I want to build
an electronic pressure regulator . It seams no one sells these.

So I built a triac circuit to control the motor current from 30-90 %
Then I built a 1-10psi pressure sensor to convert PSI from PSI to
volts.
Now I just need to control the Triac so that it outputs 95% at low
pressure and 30 % at high pressure. And porportional in between. Then
I should be able to set a comparator to adjust everything in between.

I build a zero crossing detector but the pulse width is too long and it
seems to wander around the exact zero crossing point.

Can any one suggest an appropriate proportianal circuit to use ? also I
guess I need a better zero crossing detector.

I'm using an LM324 for the op amp and comparator

thanks in advance for any suggestions or shematic locations

 

[Ian Stirling]

Hi:
I am modifying my Garage Low Pressure Spray Painter. I want to build
an electronic pressure regulator . It seams no one sells these.

So I built a triac circuit to control the motor current from 30-90 %
Then I built a 1-10psi pressure sensor to convert PSI from PSI to
volts.
Now I just need to control the Triac so that it outputs 95% at low
pressure and 30 % at high pressure. And porportional in between. Then
I should be able to set a comparator to adjust everything in between.

Neglecting everything else.
You do know that many sorts of motors will not respond to this sort of
'dimming' ?

Also, unfortunately, the better way to do this is to regulate the gas
pressure.
Say a large tank, and a regulator.