Saturday, 12 February 2011

27MHz TRANSMITTER WITHOUT A CRYSTAL

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A 27MHz transmitter without a crystal. When  a circuit does not have a crystal, the oscillator  is said to be "voltage dependent" or "voltage  controlled" and when the supply voltage  drops, the frequency changes.   If the frequency drifts too much, the receiver
will not pick up the signal. For this reason, a  simple circuit as shown is not recommended.  We have only included it as a concept to  show how the 27MHz frequency is generated. It produces a tone and this is detected by a  receiver.

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