Low-Cost Logarithmic Converter Using Opamp and Transistor

This low-cost logarithmic converter is built using op-amp and transistor. This circuit uses a Motorola MC1539G op-amp which is connected to PNP transistor. To compensate the error, this circuit need an external compensation which can accommodates wide range of input voltage and has about 200nA bias current. To adjust bias current initially, replace the transistor with 500K potentiometer and get […]

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TRIAC Crowbar For AC Or DC Lines

A TRIAC Crowbar circuit which works for both AC and DC voltage is shown in the schematic diagram below. This circuit provide overvoltage protection for electronic or electrical equipment against excessive supply voltage.  Crowbar circuit provide two level of protection. First, this protection circuit will drop the voltage across the protected equipment to near zero by shorting the voltage, and […]

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