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Oscillator simple circuit as dummy supply

Discussion in 'General Electronics Discussion' started by HomerDodd, Jun 30, 2018.

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  1. HomerDodd


    Sep 6, 2017
    Some of my previous posts described a problem with my older Cadillac. There is a permanent magnetic two-wire sensor buried deep in the transmission. I generates an AC signal, and I think, a sine wave. Minimum required output spec's to the cars computer (ECM) are 5.5 VAC and 540 Hz, when operating properly. I cannot easily get to it an replace it, as it is extensive labor. I'd rather just bypass it, since the car runs normally anyway, just the "Check Engine" light stays on. Some of the older Cadillac guys stated they use an op amp circuit, but no further details. I have came close to solving the problems with various circuits that several members provided me. Just wondering if I can make a simple 9-12 volt oscillator circuit that will produce the peak to peak sine wave at 550 Hz or more and thus place it in place in lieu of the sensor? Any examples or schematics would be greatly appreciated. Thanks !
  2. 73's de Edd

    73's de Edd

    Aug 21, 2015
    Is this being relevant to your situation ?
    hevans1944 likes this.
  3. HomerDodd


    Sep 6, 2017

    Yes. I have the P056 code. I can clear it with the onboard diagnostics, however, it returns after driving only a few hundred feet. The sensor is $20, but over $2,000 in labor to remove the engine and trans and change the sensor. It is simply a permanent magnet two wire (passive, not active) sensor. It generates AC which is fed to the EC (I'm thinking AC must be a sine wave, not square). If the voltage is too low, or possibly the Hz, the "Check Engine" light comes on. I am simply trying to feed and oscillator signal into it instead to fool the computer. It has been done, but I can no longer reach any of the Cadillac guys to ask how specifically they did it. I just need a sine wave generator/oscillator circuit the provides 5.5 volts PP and 540Hz or more. Thanks.
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