555 timer circuit to control 12v solenoid air valve (for intermittent bursts of air).

[Wal]

Hello all,

I've been meaning to make this for a while - it's a laughably simple project (for all but the electronics simpletons like myself).

So, I'm going to base my circuit on this one:

http://www.555-timer-circuits.com/flashing-led.html



...except I'll be using a 12v PS and one of these instead of an LED:



R1 and R2 control the speed at which the LED flashes - or rather (I'm hoping) the solenoid will open and close - as it is, the led flashes rather quickly - I'm planning to replace these two resistors with a couple of linear pots so that I can adjust open/close times - any recommendations for pot values I should be looking at..?

Also, the cap value? As I'm using a 12v supply will I need to change the cap - what difference would a different value make to this circuit?

Finally, will this work..?! Have I correctly assumed that R1 and R2 are independently controlling open/close times?

Any advice appreciated..!

Wal.