Free electronic circuit design and schematic diagram
Astable multivibrator or oscillator circuit is based on positive feedback. We can design such circuit using op-amp, logic gates, or transistors. Here we can rely on single capacitor capacitor and resistor for the feedback inside op-amp like transistor circuit, which works over wide range of temperature, voltages and transistor gains. The stability is pretty good, for supply voltage changes between […]
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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 […]
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In the relay’s point of view, dark activated means the relay will be activated when the light intensity fall below a certain threshold. Without hysteresis, the relay will be activated and deactivated if the sensed brightness fall under or rise above a single point of darkness level. With hysteresis, the darkness level for activating and deactivating the relay will be […]
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The circuit below is a logarithmic amplifier using an MC1556 op amp. The 10K pot is an offset adjustment. Here is a schematic diagram of one classic example of general purpose logarithmic converter circuit employing LM1556 op-amp: The popularity of logarithmic amplifier is decreasing as the microprocessor and microcontroller chips are getting lower and lower in price. Long time ago, […]
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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