Opto-Isolated-Input 4-Digit Voltmeter

The voltage that control a V/F converters will be displayed if we use a frequency counter, which is directly proportional to the input voltage. A 1 second time base will give 4 digit resolution with 1 reading per second when the V/F converters is running at 10KHz full scale. To transmit the frequency, we can use the optoisolator, so there […]

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Basic Flash Memory Programming Voltage Supply

This is a Basic Flash Memory Programming Voltage Supply circuit. This circuit uses LT1072 switching regulator to generate high voltage by driving the L1. R2 and R2 provide DC feedback for this circuit. R3-C2 and C1 control the SC roll-off. This circuit can generate supply of 12V or 12.75V depended on the R1 values. To protect this circuit from the […]

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5V Powered 4-20mA Current Loop Generator

Voltage step-up also employed in figure below, but for a different purpose. The common requirements are transmission of industry standard 4-20mA current loop signals to valves and other actuators.   Current transmitters is required by resistive line losses and actuator impedance to be able to force a compliance voltage of at least 20V. 5V powered systems usually cannot meet current […]

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Frequency/Tone Decoder with TC9400 FVC

Another application of FVC (frequency-to-voltage converter) is tone/frequency decoder. This circuit is used to determine the frequency band of an oscillation signal. This circuit is used in many application like determines the frequency band in the signal and remote control where the frequency band corresponds to a different command. This circuit uses TC9400 F/V converter to convert the frequency to […]

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Permanent Magnet Motor Control with SCR

This is a schematic diagram of Permanent Magnet Motor Control circuit. This circuit is used to control the permanent magnet control. This circuit uses alternistor triac to enhance commutation characteristics because the PM motor is a generator where the standard triac difficult to commutate properly. The full-wave DC rectification is needed for PM motors. Here is the schematic diagram of […]

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Reduced Hysteresis Diac-Triac Phase/Power Control

This is a Reduced Hysteresis Diac-Triac Phase/Power Control circuit. This circuit is used to control from 5% to 95% of full load power. This circuit can decrease the hysteresis effect to a reasonable region. It can be done because this circuit uses second RC phase-shift network. Beside that, the second RC phase-shift network also extends the range on control. This […]

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Diac-Triac Phase/Power Control without Hysteresis

Hysteresis in lamp dimmer or in other electric appliance might cause some trouble if you need a fine tuning, something like out of control. This is a circuit of Diac-Triac Phase/Power Control without Hysteresis. This circuit can eliminate the hysteresis effect. Here is the circuit: The initial condition of the timing capacitor is uniform because the (a) circuit reset timing […]

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