OpAmp question 1

[djackman]

I am working on a circuit to emulate the output of a speed/position sensor on a machine. The sensor is a magnetic pickup that reads a wheel that has 8 evenly spaced teeth with a 9th tooth for position indication.

The output of the sensor swings from +15 to -15 volts for each tooth. I have coded a microcontroller to generate the proper timing for this pulse train, but am having trouble with the output circuit.

I can easily make two outputs from the uc, one for the positive half of the wave and and one for the negative half. Is it possible to drive a single opamp (say a TL082) as inverting and non-inverting?

My background is programming not EE, getting hung up on the hardware side of things.

 

[MacGyverS2000]

It's possible, but you'd have to add in some selectable logic, and by that point you might as well add in a second op-amp, one for inverting and one for non-inverting.

What is this for? Describe the project in more detail so we can give better answers...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[IRstuff]

Don't you just want a diff amp with -15V to +15V swing?

TTFN

FAQ731-376

 

[djackman]

A diff amp or comparator looks like the way to go.

Thank you for your comments!

 

[itsmoked]

All you need is one edge per tooth. Perhaps you can rectify the output signal. Throw away the negative component.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[IRstuff]

OP wants -15 to +15 swing from uC

TTFN

FAQ731-376

 

[Noway2]

You might also want to consider a detector and one-shot generator, like the LM1815. The one shot detector will pick up the transition and generate a clean pulse while ignoring the oscillations that will occur at the front and back of the magnetic pickup pulse. The LM1815 can easily handle +/- 15V and has a form of collector output that you can use to translate the pulses into the range desired by your controller.

 

[logbook]

djackman,
Your post is quite incomplete.

You want an emulator for a magnetic pickup. Ok.

A typical simple magnetic sensor does not generate a rectangular waveform. If you have one that gives -15V for no tooth and +15V for a tooth, for example, that is a digital magnetic sensor. It requires one output from the microcontroller, this output needing amplification and level shifting. (One opamp or a few transistors and resistors). If you have an analogue sensor giving interesting shaped pulses you will need some resistors and capacitors to shape the pulse and an EE to do the work.

Post a data sheet for the sensor (or just the part number) for more appropriate help.