High-Voltage Generator with HEX FET
The schematic diagram below show a circuit of high voltage generator. This circuit uses a 4049 hex inverter as an oscillator, and you can use ignition transformer from automotive engine. A fly-back transformer is possibly usable too. The 4049 will drive the IRF731 HEX FET. The Q1 must be heatsinked. Here is the schematic diagram …[Read More]
Main Power-Battery Backup Switcher
The schematic diagram shown below is a battery backup regulator circuit, useful for memory or other low power (battery operated) but critical circuit (must continue operation on powerline failure). The one LT020 will not conduct in under line-powered condition, made possible by means of of feedback string’s arrangement. In case of main power failure, the …[Read More]
A compressor circuit shown in the schematic diagram below can produce consistent output of 1.4V P-P over entire 60dB range that is very useful for audio level/volume stabilization. As the main components, this circuit uses a 741 opamp and JFET. With input range of 20mV to 2oV, this circuit has delay time of 0.4s (decay …[Read More]
Low-Drift High-Impedance JFET DC Voltmeter
The voltmeter shown in the schematic diagram below has very high impedance. The range selector uses conventional voltage divider resistors, but since the following pre amplifier uses JFET, the divider can be designed using very high resistance series resistors. This DC voltmeter circuit also featured with low drift. This circuit uses a pair JFETs, which …[Read More]
Double-Sideband Suppressed-Carrier (DSB-SC) Modulator
When we modulate a carrier signal with amplitude modulation, there will be four frequency components as the result. The first is the modulating signal itself, the second is the frequency carrier, the the latest two are the difference and the sum of the carrier and the modulating signal. The spectrum of these frequencies can be …[Read More]
Voltage-Controlled Attenuator (Volume Control) Using FET
Using the circuit shown in the schematic diagram below, we can control the low-level audio signals with ±3V variable DC voltage. This attenuator circuit uses a field effect transistor (FET) to shunt the signal to ground. The R2 is used to control the output level (the attenuation level), but you can use other source of …[Read More]
LM1201 Video Amplifier with Balanced (Bi-Phase) Output
This is a schematic diagram of video amplifier circuit with bi-phase output. Bi-phase output provides both positive-going and negative-going signal, and can be used as balanced signaling. The main component of this circuit is LM1201. In this circuit, the inverted video is obtained at pin 10 because of the 75Ω termination to the power supply …[Read More]
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