Electrical – Simple voltage follower

bufferoperational-amplifier

I'm nowhere near savvy in the electronic engineering department, so despite having read up on op amps/buffers/voltage followers, I'm still just as confused.

I need a pure DC circuit with 2 inputs and 1 output. A 5V input, a variable .2 to 4.2 volt input signal, and the same .2 to 4.2 volt as an output (Having them match up identically is not required, just need to be somewhat close).

Current draw is very small; in the order of .5 mA. This is for a car that has a seperate computer for the 4WD function. Normally the car recieves a voltage signal (throttle position sensor) from a follower inside the main engine computer, but I installed a new computer that no longer has a built in follower. For now, I simply spliced into the TPS voltage signal, which works fine, however the extra current draw for the 4WD computer throws off the 0-100% scale.

Can anyone point me in the right direction as to what I would need to make this circuit? I'm presuming it can be done with a basic BJT or similar?

Thanks for help in advance!

Best Answer

The question you are asking is very easy to answer. In order to make a voltage follower, you need a single opamp connected in "voltage follower" configuration.

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Yous hould have a 5V line available for your TPS, you can use it to power the opamp. Make sure you use a rail-to-rail opamp so that you can go as low as 0.2V.

You will most likely need 2 opamp as most throttle pedal have 2 output for redundancy.

Last thing, what is the resistance of your pedal ? And what is the input impedance of your computer analog input ? Maybe there's another solution than buffering the signal.

Good luck