Check the regulators in the automotive section of the National
Semiconductor web site http://www.national.com. They have regulators that
are designed with the automotive environment in mind. They also have some
appnotes that talk about the hazards of this environment.

Larry


At 07:31 PM 3/29/2002 -0800, you wrote:
>   Steve, in addition to comments from Bob and Rick, check the voltage
>ratings on your capacitors. Especially if you are using tantalums. If
>you get some large spikes, you could easily destroy the cap if it's not
>rated to handle the output. Other than that, I would first pull the PIC
>and see exactly what voltages you have on those pins...
>
>   - Tom
>
>>Stephen Webb wrote:
>>
>>> I'm having trouble with a circuit.  5V regulator, PIC, and a reed relay.
>>>
>>> When I run it from a 9v source, it draws ~20 mA-40mA.  It can run
>>> "forever" without problems.
>>>
>>> When I run it from my car electric system (12v battery, alternator ~
>>> 14v) it gets very hot.  The regulator gets hot, but nothing terrible.  The
>>> PIC gets noticably warm.  Pressing your finger on it for > 5 seconds
>>> causes you to feel pain.
>>>
>>> I'm just shooting in the dark, here, but is it possible that the regulator
>>> can't deal with the "noisy" input, and the resulting output is causing the
>>> pic problems?
>>>
>>> -Steve
>
>
>------------------------------------------------------------------------
>Tom Handley
>New Age Communications
>Since '75 before "New Age" and no one around here is waiting for UFOs ;-)
>
>--
>http://www.piclist.com hint: The PICList is archived three different
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>
>

Larry Bradley
Orleans (Ottawa), Ontario, CANADA

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