T
tekniq
- Jan 1, 1970
- 0
Hi,
I'm working on a circuit to condition the AC signal from a variable
reluctance crank angle sensor.
The signal waveform amplitude varies from +- 100 mV to +- 50V depending on
RPM.
The output must be a 0V-5V square wave and switch on the negative going zero
crossing.
I'm using a standard TL082 opamp as a comparator with positive feedback
resistors R10 R11 to provide say 100mV hysterisis, I can set the trip-point
on the - input of the comp. with a trimpot.
This is the part i'm not too sure about.
As the opamp rail-rail voltage is 0-5V the imput signal must stay in
between.
I eliminate the negative half of the wave with a standard 1N4004 rectfier
diode and clamp it to max 5V with a zener diode and resistor.
I added another resistor R8 and capacitor C6 to filter the noise on the
input? but i doesn't look right to me. maybe i should put in an AC coupling
cap instead.
Also i don't know if the input resistor R8 conficts with the hysterisis
feedback.
Please examine the circuit on http://home.orange.nl/~tekniq/vr_input.jpg and
give suggestions to improve this cicruit and to determine component values.
Regards,
Martin
I'm working on a circuit to condition the AC signal from a variable
reluctance crank angle sensor.
The signal waveform amplitude varies from +- 100 mV to +- 50V depending on
RPM.
The output must be a 0V-5V square wave and switch on the negative going zero
crossing.
I'm using a standard TL082 opamp as a comparator with positive feedback
resistors R10 R11 to provide say 100mV hysterisis, I can set the trip-point
on the - input of the comp. with a trimpot.
This is the part i'm not too sure about.
As the opamp rail-rail voltage is 0-5V the imput signal must stay in
between.
I eliminate the negative half of the wave with a standard 1N4004 rectfier
diode and clamp it to max 5V with a zener diode and resistor.
I added another resistor R8 and capacitor C6 to filter the noise on the
input? but i doesn't look right to me. maybe i should put in an AC coupling
cap instead.
Also i don't know if the input resistor R8 conficts with the hysterisis
feedback.
Please examine the circuit on http://home.orange.nl/~tekniq/vr_input.jpg and
give suggestions to improve this cicruit and to determine component values.
Regards,
Martin