>RE using a 7806 voltage regulator from Radio Shack
>You should add two .01mf capacitors; one from the input to
>ground and one from the output terminals to ground.
>These devices like to oscillate and will heat up
>possibly fail and cause RF noise to other devices like radios.
I agree, they are prone to oscillation - some manufacturers' regulators more
than others. (I had one 7815 that oscillated at an ultrasonic rate even with
10 uF on the in/out leads working into a purely resistive load! It's now in a
landfill somewhere!)
For this reason I nearly always shunt the input and output with around 1 uF
(tantalum or electrolytic) caps in printed-circuit or perfboard-mounted
regulator circuits. But on vehicle applications of the three-terminal
regulators I have not used the caps and have yet to see any oscillation
problems, so I did not complicate my suggestion by describing their use.
I suspect the typical automotive wiring path tends to keep the input and
output wires separate, and the large ground plane formed by the auto chassis
helps keep them under control, too. But to be absolutely safe, it is wise to
add bypass caps.
Steve Johnston
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