30-Khz Bandwidth High Linearity Opto-Isolated Amplifier

Using optocoupler to directly transfer a linear (analog) voltage would produce  a large unpredictable linearity error, which is also sensitive to temperature changes. By using frequency modulation, the total system’s linearity will  depend only on the linearity of the V/F and F/V converter, which is fortunately cancel each other if we use similar devices with similar non-linearity error characteristic. A […]

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Selectable Voltages 6V, 9V, and 12V Linear Voltage Regulator

  We can build a multiple voltage power supply 6, 9, and 12V  (AC-DC Adapter) with the circuit shown in the following schematic diagram.  Not only provide multiple voltage output with single voltage supply, this circuit add the benefit of regulating the voltage for better stability. The TIP31 transistor should be installed with proper heat-sink to prevent overheating. A transformer […]

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Phase-Sensitive Sinusoidal Signals Detector

Using the phase sensitive detector circuit below the magnitude of sinusoidal signal can be measured. Beside that, this circuit also can be used to measures 180°-out-of-phase inputs with proper polarity. But, it depends on the relationship to the reference with less than 1% error. This circuit uses a AD741J op amp. Here is the schematic diagram of the circuit and […]

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