I have found the old thread by John Banks and constructed, well nearly, an LED AFR gauge.

The question I have is this, can the IC used switch a realy or is it only suitable for LED's? I want to make a cut out switch to turn off NOS if the AFR's go too low, just as a safety measure.

The old 741 IC may be better?

Opinions/ideas welcolmed.

Wayne.

 

The lambda sensor voltage may drop when the sensor heats though even though it is not lean.

741 is split rail power supply, but you can get single rail op amps or comparators.

Alternatively if you get the LM3914N to feed a Darlington transistor that could control a relay - eg TIP122 or TIP127 depending on hwo you want to switch the relay. I think you would want it in bar mode so that when a particular LED level goes out you remove the power to the NOS?

 

John, thats right. The nos should have the power removed when the AFR goes low.

Thanks for the reply, off to build complicated circuits (for me anyway).

Cheers,

Wayne.