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good circuit design used for specified function

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SubnetMask

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Circuit Design help

I need help designing a circuit. I can build just about anything as long as I have something to build off of. My problem is I'm not very strong at designing the circuits.

I'm pretty sure what I need is an Oscillator circuit running at 125kHz. What it is for is re-pairing Tire Pressure Monitor Sensors on my 2004 Silverado. The description that I found states that "The sensor is stimulated with low frequency magnetic field (125kHz, may or may not be modulated). This will cause the sensor to transmit." It doesn't need to be powerful. The field really only needs to extend about 6".

The sensors can also be paired by letting air out of the tires, but it would be much nicer (and more reliable) if I could build a tool to force the sensor to pair up.

Does someone have a good circuit I could use for this function?

Thanks in advance,
Dave
 

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pauloynski

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Re: Circuit Design help

Google for RFID circuits running at 125kHz
 

SubnetMask

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Re: Circuit Design help

pauloynski said:
Google for RFID circuits running at 125kHz
Well, I have, and most of what I've found is for complete readers that'll recieve the RFID signal as well as generate the 125kHz signal, and there are a TON out there at that. I'm looking to make the simplist circuit possible.
 

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Re: Circuit Design help

pauloynski said:
http://www.discovercircuits.com/DJ-Circuits/125kpowerosc0.htm

Added after 1 minutes:

Please be cautious because the ressonant output stage may show high voltages.
Thanks! Just to be sure I understand it correctly, the 74AC04 is a 14 pin IC, and pin 14 is incoming +5, pins 3, 5, 9, 11, 13 and 2 are tied together, pins 4, 6, 8, 10 & 12 are tied together and output to the cap which powers the ferrite rod?
 

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pauloynski

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Re: Circuit Design help

Yes. Tune the values of L and C to obtain maximum output at 125kHz. If it is correct the voltage will decrease when you place the coil near the sensor. This means you´re powering the sensor.
 

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