[sdiy] Power supply ripple

[James Dunn]

Hi all,

I have a 555 timer which is driving a solenoid and running off a 9 volt 
battery, however the negative spikes show up on the 9v power supply rail 
and therefore I'm having trouble with other circuitry I want to add. Is 
there a way to remove this ripple? I've tried caps across the 555 and 
the battery, and I've tried a 5v regulator but the ripple is still 
there. The circuit is using about 18ma, so maybe I should use a separate 
battery for the other circuit?


thanks

James