What pissed me off the most is that, one month before my final year project submission, i requested a part from Element14. It took 2 weeks to reach me. however, it was not about taking 2weeks. When i finally received the envelope It was empty.. Nothing was there.
i Tried to call them couple of times but unfortunately the dead line was over..
and nothing return to me neither my money nor the component..
that was my story with Element14 Community..
In my circuit i used a transformer to step down the wall outlet (230V/50Hz) to 24V @ 3A center tap, to be used as the input to a rectification circuit consisting of bridge rectifier and a filter cap.
after that, there is a crystal oscillator circuit operation at 13.56 MHz followed by class B (N-P) power amplifier to amplify the oscillator output to the transmission coil.
oscillator circuit diagram can be shown here:
*( The output of the oscillator is not directly connected to the transistor gates, an additional operational amplifier were used to reduce the crossover distortions. A negative feedback loop is connected the output of the transistors to the inverting terminal of the op-amp, the oscillator output connected the non-inverting terminal and the output of the op-amp is connecting the transistor gates).
this is simply, how my transmission circuit would look like.
my problem is, how to get the right value of the components that operates at the specified frequency and also taking into account the voltage & current feeding the circuit, such as P and N Transistors, op-amp, and the IC Hex-inverter which completes the oscillator circuit.
also which type of transistors should be used in this project Mosfet or Bjt?
Your responds will be much appreciated..