relay Do I need a protection diode here

Posted on Feb 5, 2014

I have an automotive relay (from a scan of a workshop manual I`m afraid) which is rather more complexly wired up than the relays I`m familiar with. In this diagram: B/G - holds high if another condition is met (engine temp too high), to prevent the relay energising. (As far as I can tell. this is the correct logic for sure, not sure if it tech

relay Do I need a protection diode here
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nically works that way!) I understand how the relay works at the moment. However, what I plan is to cut (L) and insert a device which will prevent the relay energising unless some further conditions are met. This is achieved with some logic gates and an output transistor, which will `join` L when my device allows it. What I can`t tell is if I need a protection diode across the relay to protect my transistor And if I do, would this interfere with the logic provided by the combination of L, L/B and B/G

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