chips occasionally blowing?


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  1. #8
    Join Date
    Feb 2005
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    Toronto, Canada
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    here's the thing, the circuit has alot of ports, like for the tip122s, but they're not being used as of yet, only ONE of the 19 boards I used a tip122, and that one hasn't blown, it's perfectly fine... which is odd,( I'll obvisoly add the resister as you suggested though for the next revision, I have no qulams about redesigning and reprinting the board. I need to make more anyways).

    what's being driven from the pic is the mac floppy motor, and the counter chip.
    so the circuit isn't really as complicated as it has space for, there's really only like 4 things on it usually.

    I'm wondering if I need to some how buffer the incoming voltage??? is the 5v clean enough? should there be a resitor somewhere for the pic voltage incoming or outgoing... I mean, really, all I cna think of (other than the tip problem, which hasn't been the source yet) is that the mac floppy needs a diode on the signal pin, perhaps theres feedback being thrown back to the pic? I send a HIGH pulse for 800 (pause) then the motoer does a rotation once around.

    and running the 16f628a on internal clock, is this bad? I'm wondering if I've hooked in one of the traces to the pic wrong or something....

    also, a few osc crystals blew, but I've heard that can happen alot...? so i started using the 628 to avoid external clocks
    Last edited by kenpo; - 21st May 2006 at 21:18.

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