Free Simple Circuit Diagram
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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This is a 100MHz Varicap Oscillator circuit. This circuit can provide modulation signals less than 28V and frequency deviation of 28 MHz peak-to-peak. This circuit uses two variable-capacitance diodes which is connected to d-c bias and audio modulating signals in parallel connection and connected in series to r-f. Here is the circuit: [Circuit’s schematic diagram source: seekic.com]
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The UHF motion detector below operates on the Doppler radar principle. A radial signal is created by the oscillator (Q1). Some of this energy is reflected back to the generator by an object in the radiated field. The reflected signal will have a different frequency because of Doppler shift if the object is moving. Q1 is an oscillator coupled to […]
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This is a linear FM detector circuit. This circuit usually is used in telemetry applications and wide range of analog communications. The main part of this circuit is a XR-2211. This circuit has an external buffer/amplifier that is needed due to the high-impedance output at pin 11 of XR-2211. This circuit also has a post-detection filter Rf/Cf. This circuit produce […]
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