Working principle of signal generator

The signal generator is used to generate a sinusoidal signal (low frequency) with a frequency of 20 Hz to 200 kHz. In addition to having a voltage output, some have a power output. Therefore, it is widely used for testing or overhauling the frequency characteristics, gain, and passband of low-frequency amplifiers in various electronic instruments and equipment, as well as for external modulation signal sources of high-frequency signal generators. In addition, when calibrating an electronic voltmeter, it can provide AC signal voltage. The principle of low frequency signal generator: The system includes a main oscillator stage, a main oscillator output regulating potentiometer, a voltage amplifier, an output attenuator, a power amplifier, an impedance converter (output transformer), and an indicating voltmeter.
Schematic diagram of a square wave generator with adaptive power supply
The main vibration stage generates a low-frequency sinusoidal oscillation signal, which is amplified by a voltage amplifier to meet the requirements for voltage output amplitude. The output voltage can be directly output through an output attenuator, and the magnitude of the output voltage can be adjusted using the main vibration output adjustment potentiometer.
Schematic diagram of a square wave generator with adaptive power supply
The circuit shown on the right is a square wave generator without power supply, which can be used as a simple signal source for electronics enthusiasts and laboratories. The circuit is an adaptive square wave generator composed of six inverters CD4096. When a small signal sine wave is input at the input terminal, the signal is transmitted in two paths, one of which is a C1, D1, D2, and C2 circuit, completing the rectification and voltage doubling function and providing working power to the CD4096; The other path capacitor C3 is coupled and enters the input terminal of an inverter of the CD4096 to complete the signal amplification function (the inverter can be used as an amplifier when working with small signals). The amplified signal is processed by a later stage gate circuit, converted into a square wave, and then output through pins 12, 8, and 10 of CD4096. The R2 at the output terminal is an adjustable resistor to ensure that the output signal is adjustable from 0 to 1.25 V. The square wave generator circuit is simple and easy to make, so it can be used as a 50 Hz square wave generator powered by mains power. During production, the sinusoidal wave of 220V mains power should be isolated and depressurized by a transformer (1 to 0.75 V) before being input to the input terminal of the circuit to ensure safety.