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A question about the input section of the V3 main board

Posted: Tue Sep 22, 2009 11:48 am
by rusty105
A question about the input section of the V3 main board

On the V2.2 board you have D1, 2, 3, 4, 11 as protection diodes, but not on V3.0, at least not on the schematics. It looks like they were there but removed and they don't show up. Any reason why these were omitted? I know the sensors pose little chance of more then 5V, BUT as explained in this thread viewtopic.php?f=38&t=3160 the HEGO could accidently feed battery voltage (12V+) to the circuit if not hooked up correctly. Is it a misprint on the schematic, or is it not needed on a V3 main board?

Rusty

Re: A question about the input section of the V3 main board

Posted: Wed Sep 23, 2009 5:08 am
by Matt Cramer
The diodes tend to create more problems than they solve as they distort the signal at the far ends of its range. The chip has some measure of built in overvoltage protection.