This is a design circuit for receiver circuit that can be completed for the transmitter. The receiver is a super-regenerative design. This means it is self-oscillating (or already oscillating) and makes it very sensitive to nearby signals. It is much more sensitive than receiving a signal and making it oscillate a transistor. This is the figure of the circuit;
A super-regenerative design is not universally used because it is much more noisy than conventional reception and is not suitable for voice transmission. However it is used in simple walkie-talkies and this is why they are so noisy - as will be shown at the end of this article. When a signal of the same frequency as the super-regenerative circuit passes near the antenna, the circuit has difficulty radiating a signal. This means the circuit current VARIES. These variations appear across the 2k2 load resistor as a change in voltage and the signal is picked off via a 100n capacitor and passed to the second and third stages for amplification. The 22n across the first stage is designed to remove the high-frequency component from the waveform. If this were not present, the circuit would never change state. The receiver is tuned to the frequency of the crystal in the transmitter via a slug-tuned coil in the collector. When the transmitter is off, the receiver picks up background noise and amplifies it to produce random-noise. This is amplified by the second transistor and passed to the third via a 0.47u electrolytic. This electrolytic is designed to keep the third transistor ON for the major part of the time and it does this in a very clever way. We will assume the supply has just been turned on and the second transistor is not receiving a signal. The 0.47u will be uncharged and it will charge via the 10k collector resistor and the base-emitter junction of the third transistor.
A super-regenerative design is not universally used because it is much more noisy than conventional reception and is not suitable for voice transmission. However it is used in simple walkie-talkies and this is why they are so noisy - as will be shown at the end of this article. When a signal of the same frequency as the super-regenerative circuit passes near the antenna, the circuit has difficulty radiating a signal. This means the circuit current VARIES. These variations appear across the 2k2 load resistor as a change in voltage and the signal is picked off via a 100n capacitor and passed to the second and third stages for amplification. The 22n across the first stage is designed to remove the high-frequency component from the waveform. If this were not present, the circuit would never change state. The receiver is tuned to the frequency of the crystal in the transmitter via a slug-tuned coil in the collector. When the transmitter is off, the receiver picks up background noise and amplifies it to produce random-noise. This is amplified by the second transistor and passed to the third via a 0.47u electrolytic. This electrolytic is designed to keep the third transistor ON for the major part of the time and it does this in a very clever way. We will assume the supply has just been turned on and the second transistor is not receiving a signal. The 0.47u will be uncharged and it will charge via the 10k collector resistor and the base-emitter junction of the third transistor.
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