> Designing the protection circuits so the interface is not destroyed
> by spikes from the car electrical system or from the frame/ground/
> building will be harder than the amplifier proper imho

The tacho he's got connects to the ignition coil so must have protection
for that. The idea is to use the tacho as a readout and take a tap off
some point in circuit (the meter movement ?) and amplify it to 8V /
1000rpm
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