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  1. H

    Op Amp with a/c output

    Wow again!! Thanks so much for the help and explanation. Sorry I dragged this out so long. I really needed the help from the people in this forum.
  2. H

    Op Amp with a/c output

    No, it's there. Just hover over "article" and it takes me to a PDF article. Thanks !
  3. H

    Op Amp with a/c output

    WOW !! Thanks for the details. A few questions: which pin do I input the supply voltage from the car? Is Q1 a transistor? Is UA1 and op amp LM339? Are those values below the capacitors exactly what I need to ask for at the store, along with all the diode numbers? Thanks again, this is an...
  4. H

    Op Amp with a/c output

    Exactly right Bob. The transmission otherwise runs normally. The sensor just needs amplification. The car otherwise has clean emissions. No tampering with the system involved here.
  5. H

    Op Amp with a/c output

    Thank you very much. A schematic or diagram would be such a great help to me, so I can buy the materials, and build it. Much appreciated !
  6. H

    Op Amp with a/c output

    Harold: can you give me a schematic of how to build/install this circuit? Thanks.
  7. H

    Op Amp with a/c output

    It is not illegal if the code is cleared, as the onboard diagnostics allow the owner to do this, and I already have cleared it several times. The car otherwise passed the tailpipe emissions test, which the system has not been tampered with. Emissions system tampering is illegal, no electronic...
  8. H

    Op Amp with a/c output

    Yes, and tougher requirements here in California. The first thing the smog inspector does is to verify the "Check Engine" light is off. If it is on, the test is over, automatic failure. Then they check for tampering or missing equipment. If the visible test passes, then they move onto the...
  9. H

    Op Amp with a/c output

    Bearing in mind the previous discussions, can one of you draw up a quick schematic of how exactly I need to build it on a circuit board, how to feed the voltage in and out. I know this is asking a lot, but I really want to get it right, so I don't blow the fuse, PCM or other circuit. Really...
  10. H

    Op Amp with a/c output

    Thanks again, very helpful. If it's no trouble, can you maybe post a schematic or drawing of the circuit, including how to input the DC battery voltage and the output "amplified" AC? Remember, I only need 8-10 VAC to send to the computer to "fool" it into thinking the sensor is good, thus...
  11. H

    Op Amp with a/c output

    Update: I hooked the multi-meter to the two wires inside the car and drove it. Look at my picture below and see the results. The one that is most puzzling to me is the meter positive lead hooked to red/white wire and the negative lead hooked to ground. At idle, and parked I get DC battery...
  12. H

    Op Amp with a/c output

    Thanks Bob ! Could it be possible to be a two wire Hall sensor; one with supply voltage and one with output?
  13. H

    Op Amp with a/c output

    Since it only has two wires, could it be that both wires are AC self generating output, with no need for a voltage supply signal from the car's battery? For comparison, I read that 3 wire Hall sensor needs a reference voltage signal.
  14. H

    Op Amp with a/c output

    Excellent. Thank you for your patience and explanation. I had some general ideas, but nothing specific. So in a nutshell, if I understand correctly, the 13 volt DC signal will be the Vin and the comparator can be adjusted for the desired output with potentiometer? If I can simply adjust for 7,8...
  15. H

    Op Amp with a/c output

    No schematic, other than the harness picture already posted. The two wires simply terminate into the ECU/PCM. Nothing else branches from them. Today I measured the voltage on the harness going into the ECU. One had nothing, the other had battery voltage, 13 VDC. Could that wire be shorted to...
  16. H

    Op Amp with a/c output

    It is a '95 Seville. From what I've read, it is a Hall sensor; the trans shaft has a toothed wheel which picks up the signal only when in gear and moving. The gear does not move when in park or neutral. Interesting, that I can clear the code, sit at idle and never have the code comeback. Once I...
  17. H

    Op Amp with a/c output

    I grounded the negative probe of the DMM to the frame and clipped the positive lead to one wire. At first on the AC setting, it bounced all over, flashing on and off, almost like trying to read a frequency or wave, and funny enough 7-8 volts flashing off and on. I changed the range and it read...
  18. H

    Op Amp with a/c output

    There are two wires going to the sensor. I scraped away a slight bit of insulation on the wiring near the trans, about a foot from the actual sensor. I then scraped away some insulation on the two wires in and out of the PCM which is located inside the car near the glove box. Definitely AC...
  19. H

    Op Amp with a/c output

    I don't have the actual manual. I was quoting what guys on the Cadillac forum quoted from their manual and posts. All of them who have correctly functioning sensors have measured the supply voltage signal (from the PCM) as 1.5 VAC approx and over 5 VAC output back to the PCM. Whatever I can do...
  20. H

    Op Amp with a/c output

    Thank you for the info. Yes, the cars computer (PCM) sends 1.5 VAC (it is AC per the manual) to the input speed sensor. The sensor, if working correctly, will return 5VAC or more (some guys have measured 9,10, 12 VAC) to the PCM for smooth shifting calibration only. So, any circuit that take...
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