Free electronic circuit design and schematic diagram
Zero crossing detector is used to convert sine wave or other signal into square-wave, the output should be low if the input is negative and high if the input if positive. Many zero crossing detector use split supply (symmetric supply), but this zero crossing detector circuit only need a single supply, thus suitable for battery-operated circuits. Here is the schematic […]
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Using a single supply quad comparator LM339, LM239, LM2901, LM2901V, NCV2901, or MC3302, we can build a square-wave oscillator with simple circuit and formula. Here is the schematic diagram: This circuit is suitable if you need many square-wave oscillators in one circuit, since the quad packaged comparator provide four comparators in one single integrated chip. [circuit’s schematic diagram source: Motorola […]
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This circuit has similar function with inverting comparator with hysteresis, but the output is not inverted. The output will be high if the input is higher than the upper threshold point, and the output will be low if the input is below the lower threshold point. Here is the circuit’s schematic diagram: What will happen if the input is between […]
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Comparator with hysteresis (Schmidt trigger) can be built using LM339, LM239, LM2901, LM2901V, NCV2901, or MC3302 quad single supply comparator integrated circuit chips. Here is the circuit’s schematic diagram and formula: This circuit’s output will swing to high or low using two threshold values. If the last output is high, then the output can be changed to low if the […]
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If only a 5 volt positive supply is available and you need a negative voltage for op-amp or other biasing purpose, the you can generate the negative supply from the positive supply using this circuit. This circuit give same functionality with our previous 555 switching circuit, but now we use a CMOS inverter gate. Using CMOS component allow our circuit […]
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Here is a schematic diagram of electret microphone pre-amplifier using LMV721 op-amp. because the LMV721 has low noise and low power features, it would be an ideal choice for battery powered microphone preamplifier. The LMV721 is connected as an inverting amplifier. Resistors, R1 =R2 = 4.7k, sets the reference at mid point between VCC = 3V and ground. Thus, this […]
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Balanced input has three connections, ground, positive signal, and negative signal. When we trace the signal using oscilloscope, if we take the ground as the reference, then the negative signal and the positive signal has similar shape but with inverted polarity. If we measure the signal between positive and negative output, the we have two times larger signal than what […]
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