Free electronic circuit design and schematic diagram
This is a 230VAC Temperature Fan Control circuit. This circuit is used for 230Vac operation. The R9 can be changed to 15K 2W, if the AC operation is 115V. This circuit uses the principle of Wheatstone bridge. The Wheatstone bridge is made from R3-R4 and R1-P1. P1-R1 produce a temperature-sensitive “variable” voltage and a fixed two-thirds-supply “reference” voltage is produced […]
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This is a Variable Q Twin-T Notch Filter circuit. This circuit is used when low Q is needed. The Lower Q gives some advantages in rejecting the signal where the signal deviate slightly from the null of the notch network. The Q of this circuit can be adjusted from 0.3 to 50. This circuit has two voltage follower. The second […]
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This is a Bootstrapped Twin-T Notch Filter circuit. This circuit can generate high Q by combining the twin “T” with LM102 voltage follower. The generated Q is greater than 50. This circuit uses small capacitors since the LM102 uses the large resistance values in the “T”. Beside that, voltage follower also used as buffer that gives high input resistance of […]
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This a Sallen and Key Lowpass Filter circuit. This circuit is a second-order active filter. This circuit can be changed to highpass filter by interchanging capacitors and resistors. This circuit is featured with buffer. The buffer of this circuit is op-amp which configured in inverting configuration. This circuit is stable, since this circuit has positive feedback and never overcomes the […]
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This is a Twin-T Notch Filter circuit. This circuit is a filter that can remove a certain frequency band. This is a passive filter that uses two filters in parallel, high-pass and low-pass. The high-pass filter is lower one and the low-pass filter is the upper one. This filter has a problem with the input resistance. When this filter is […]
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This is a complement phase inverter circuit. Sometimes this circuit called a paraphase amplifier circuit. This circuit has two output signals that is have sufficient “headroom” because this circuit is biased. The transistor will be saturated when the collector decreases, the emitter voltage increases and set the limit. Here is the circuit: This circuit can produces a peak to peak […]
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This is a voltage multiplier circuit. This circuit uses a doubler principle to multiply the voltage. This circuit has some advantages like low current supply, attractive high voltage that is needed for photomultipliers and cathode-ray tubes. Besides that, this circuit is inexpensive. This principle is also used in the Cockroft-Walton accelerator for charged particles the Cockroft-Walton accelerator for charged particles […]
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