Free electronic circuit design and schematic diagram
This is a Norton amplifier circuit with dc gain control. This circuit is formed by one section of an LM3900. This circuit has dc gain-control input ranges from 10 V for maximum gain down to 0 V for minimum gain. Here is the schematic diagram of the circuit:
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This is an active antenna circuit with gain. This circuit is used to bost the signal. This circuit is made from a few transistors and other components. This circuit can provide RF gain of about12 to 18 dB. This circuit uses Q2 as a voltage amplifier. the RF signal direct-coupled from Q1’s Source terminal to the base of Q2. The […]
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This voltage regulator circuit gives a stable 5V output from unregulated inputs (more than 5V). The stability of the output voltage is good enough, only change less than 0.1 volts when the load current changes about 60mA. Here is the schematic diagram of the circuit: The basic principle of the voltage regulation rely on the mechanism of keeping the the […]
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This voltage monitor has two threshold, VTH for undervoltage and VTH’ for overvoltage. Using the component values shown in the schematic diagram below, this circuit give 6V for VTH and 15V for VTH1. Above 6V, the LED indicator of this voltage monitor circuit will increase the flash rate until reach 15V. This circuit will stop flashing at voltage below 6V […]
Read moreThis is a video of the engine coolant temperature (ECT) sensor. This video explains how the ECT sensor works. As the temperature goes up, the voltage goes down. Only two terminals are used, the ECM ground and the 5V reference terminal. The ECM ground is connected to the pin number 5 and the 5V reference coming from the ECM/PCM. Here […]
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A meter amplifier can be designed using LM10 integrated circuit (IC). The accuracy of full-scale sensitivity is good for over 15°C to 155°C at 10mV and 100nA. Here is the schematic diagram of the circuit: R5 is used to correct the offset voltage error, while R4 is used to balance the bias current. The zero calibration uses the reference voltage […]
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This circuit gives a changing-color LED display, where a LED will emit a dynamic shifting color, from red to green smoothly through yellow. The circuit uses NE556 dual timer, equal to two 555 IC but in only one package. The oscillators is set at different frequencies. The high frequency (upper part) is used to construct a PWM signal, and the […]
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