DC, RMS, And Peak-to-Peak High Impedance Voltmeter

Analog meter normally doesn’t have high impedance since they don’t have buffer circuit inside. With active buffering, the input impedance of this circuit depends on the impedance of the op-amp. You can use other op-amp for higher impedance, but a low-cost 741 is enough for may application. The rectification inside the feedback loop path remove the effect of diode’s voltage […]

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LM2917 Automotive Tachometer

Variable reluctance magnetic is not derive all inputs. For example in spark ignition engines, the inputs are derived from the spark coil. Below is figure of an interface circuit for this situation. We can set up any number of cylinders using this tachometer by linking the appropriate timing resistor as illustrated. We can use a 500ohm trim resistor to set […]

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CD4093 Water Level Sensor (Detector)

This water level sensor (detector) circuit uses a standard NAND logic gate to produce oscillation and to detect the water level. Oscillation is included inside this circuit to provide alternating current (AC) source for probe electrodes, to achieve a corrosion free operation. With AC source, the process of electrolysis is done in both direction, neutralizing the process of ionic transfer […]

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