Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Increasing sensor voltage

Status
Not open for further replies.

EmeraldW

New Member
I have a sensor that puts out a voltage of .1 to 1.1 volts. I want to be able to take the output voltage and increase it by 5-10% before it goes into the input of the controller. Whatever method I end up using needs to be able to vary it's voltage with the sensor's output.

I thought about using a small transformer but I figured I would ask first. I found some 3.3v primary / 5v secondary transformers but that is a bit too much of a jump. Thoughts?
 
Is the sensor voltage AC or DC? If AC, what frequency? DC wouldn't work with a transformer, of course. An op-amp solution is probably what you need.
 
You also need to know if the 0.1 to 1.1V is into an open-circuit, or if not, then what is the input impedance of the exisiting downstream controller....
 
I can't find any datasheets on the controller but it is an automotive PCM. Mainly the O2 sensor input.

I was also thinking it might be better if it had more control over the voltage then just being increased X amount over the original. How about using a PIC to read the original voltage and controlling a digital pot to send the desired voltage back out?
 
How about using a PIC to read the original voltage and controlling a digital pot to send the desired voltage back out?
That is probably the answer if you want to do non-linear mapping of the signal; otherwise for linear scaling and off-setting an op-amp would be much simpler.
 
Since the PCM supplies both the ground and the signal to the sensor and I need to send a signal from a separate power source, do I just have to connect the two signal sources grounds?
 
It is common practice to avoid grounding a sensor to the frame (car body) locally to prevent currents that flow along the frame from coupling into the sensor signal (gound loop). Instead, even if one end of the sensor signal is referenced to 0V, a separate wire runs between the sensor and controller. If you adding a powered sensor with its own opamp, I would isolate the ground from the frame, and carry it back to where the ECM is grounded..
 
The sensor casing appears to be grounded to the body but it uses four wires. Two are the power and ground for the internal heater at 12v and the other two are a ground from the PCM and the return signal which runs in the .1-1.1v range. The 12 power and ground come from a power distribution box but the signal line and ground come from the PCM. I am going to run two new lines from the sensor direct to a new box with this project board and then output the new signal lines back to the PCM.
 
Last edited:
Hego sensors come with various o/p wires from 1 to 4.
Yours being a 4 sounds like the heater are 2 seperate wires and the sensor head are a further 2, none may be connected to the chassis, check it with a meter.
You can just ground one of the sensor o/p wires to produce a single voltage o/p, if you do that take the ground wire to the op amp circuit and then ground it.
A better way to amplify the output is probably to use an op amp configured as a differential amp, or a instrumentation amp, you'll also need some compensation to prevent noise from getting to the controller.
 
Last edited:
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top