I need a circuit built

Thread Starter

dto

Joined Apr 25, 2011
6
I'm an automotive service tech. I need this component built to boost a signal of a sensor. Now why do I not replace the sensor? Because, doing so would require 15 hours of labor. The signal from the sensor is 'weak'.
 

Jaguarjoe

Joined Apr 7, 2010
767
The inputs to the op-amp are backwards. Your gain setting resistors should go to pin 2 and your input from the VSS should go to 3.
One of the power supplies is backwards. Pin 4 should get a negative supply and pin 7 should be positive.
There are more modern op-amps to use than the 43 yo 741.
Most likely the VSS signal starts at 0 volts and goes positive. There are no negative excursions. You can find a single supply rail to rail op-amp and eliminate one of your 6v batteries. Change the other battery to 9v and you can use a common PP3 battery to power it if the PCM can take the higher voltage.
 

Thread Starter

dto

Joined Apr 25, 2011
6
I don't know much about electronics. I got the schematic from a different fellow who made that same device his vehicle. If there is a better method, or technique it'd be appreciated.
 

Jaguarjoe

Joined Apr 7, 2010
767
Ok, if you want the negative output you will need to stick with dual batteries.

As I said before the pins are not correctly shown in the drawing.
Pin 2 is the (-) input, it gets the junction of R1 and R2.
Pin 3 is the (+) input, it gets the VSS signal.
Pin 4 is the (-) power connection. It gets (-) 6 volts, referenced to gnd.
Pin 6 is the output, it is ok.
Pin 7 is the (+) power connection. It is ok.

This explains how it works:

http://www.allaboutcircuits.com/vol_3/chpt_8/5.html
 

Thread Starter

dto

Joined Apr 25, 2011
6
I decided to build the circuit myself. But, i am a little bit confused. I've 2 sensor wires. It appears, one sensor wire is cut and fed in to the amp. But the other wire looks like its spliced in to the other wires?
 
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