Free electronic circuit design and schematic diagram
This is a Low Distortion Crystal Oscillator circuit. This circuit generate a sinewave that has low phase noise and distortion. This circuit can be used to perform a crystal with less than 1mV dissipated in crystal. The crystal is used to filter the signal current. If the impedance loads is low, the JFET will drive the impedance. when the loads […]
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This is a Voltage Controlled Oscillator (VCO) circuit. This circuit is based on Hartley oscillator. The frequency depend on the value of C1 and L1. The oscillation-frequency will change as the change of the capacitance in the varactor BB132 by The Vtuning voltage. The maximum frequency that can be changed is determined by th value of C2. For large frequency […]
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We can say in simple words that AFC will lock the receiver to any valid RF signal. Below, we can see a basic block diagram of an receiver. The VCO is mixed with the RF signal which enter the mixer (yellow). The VCO can be a coil and a tunable capacitor. To bring out the sound from the FM signal, […]
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FM demodulation can be done with phase locked loop (PLL), and this method is common in high-end communication system. This system uses TC9400 that has high linearity. Using TC9400, the performance of phase-locked loop will increases greatly. That will give very precise tracking of Vout with respect to Fin. Here is the block diagram of the FM demodulation with a […]
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This is a Mini MW (Medium Wave) Transmitter circuit. This circuit consist of combination of transistors SA103 and SA101. Those transistors is used as oscillator and modulation signal amplifier. Here is the schematic diagram of the circuit: The transistor is of germanium type, but I think you can replace it with silicon type from the high frequency one. The inductors […]
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This amplifier has VHF (very high frequency) and UHF (ultra high frequency) response, you can use it for receiver booster for example. Here is the schematic diagram of the circuit: The current consumption is very low, under 20 mA for 14V voltage supply. Lower current consumption can be achieved if we use 10V power supply, the current consumption would be […]
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Using this automatic probe, you can see measure both audio signal (AF) and radio signal (RF). If audio signal is being measured, the path of the signal is via C1. Audio signal can’t pass the C2 since the capacitance is very small and having very high impedance for audio frequency signal. If you measure high frequency (radio frequency, RF), now […]
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