Free electronic circuit design and schematic diagram
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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This is a frequency source system that is controlled by a digital (microprocessor/microcontroller) system. This circuit produces a square wave signal with adjustable frequencies. Here is the block diagram of digitally controlled frequency source system: This frequencies are controlled by microcontroller register, counter or thumb-wheel switches. This system can be used in many applications like numerically-controlled machine tools and computer-controlled […]
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It is advantageous to convert the analog signal into a digital signal, which is less susceptible to noise pick-up when transmitting analog data over long distances. It is very easy for noise to interfere the amplitude of a signal, but it would be harder to change its frequency. The TC9400 converts the input voltage into a pulse or square wave […]
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Look at the schematic diagram of a circuit below, imagine if the capacitor C1 is not charged and the power is off. There will be no current flow and Q3 will be open. The Base of Q3 will be high and the Base of Q2 low. The circuit is in stable condition and nothing happening. Power will flow through the […]
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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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Programming old EPROM devices needs high voltage, and this is a circuit of high repetition rate Vpp programming supplies. This circuit is used for memory programming that need higher repetition rate. This circuit produces the Vpp continuously by the switching regulator that runs continuously. To preclude any possibility of inadvertent Vpp output, the switching regulator mus t be turned of […]
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The TC9400 converts the analog input (Vin) ito frequencies (10Hz to 100KHz) which can be used to modulate an RF transmitter in a telemetry system. At the other end, The RF signal is picked up by receiver and it’s demodulated back into the 10Hz to 100KHz spectrum. A count linearly proportional to the original analog voltage (Vin) is given by […]
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