Free Simple Circuit Diagram
This is a Portable light-level meter circuit with five-decade dynamic range. This uses a single cell battery as the power supply. To calibrate this circuit, use an appropriate illumination, then adjust R2 so that the output equals the reference. To make this circuit give output meter follows standard light meter, adjust R2 and R6. Maybe there is an error at […]
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This is a battery tester circuit.This circuit is used to indicate whether the level of a battery voltage is normal, under-voltage, or over-voltage, very useful to make sure an electrical system will works properly. This circuit displays three classes of voltage level condition: high, low and normal. This circuit defines high level voltage if the voltage is more than 15 […]
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This is a metal locator circuit. This circuit is useful to detect metal. This circuit uses a AM radio and one-transistor oscillator. This circuit is inexpensive. The correct bias is provided by R1 and the frequency of oscillation is determined by search coil, C4 and C3. The search coil is formed by inductor which has varied inductance depend on the […]
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Notch filter is a filter that remove a certain B. Ideally a notch filter will remove only single point of frequency component, but practically it will remove a limited range of frequency spectrum. The spectrum should have very small bandwidth to approximate an ideal notch filter. The circuit diagram design below is based on passband gain of 3 and Q […]
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