Wiring Schematic Diagram

This FM wireless microphone is easy to build and has a large benefit of transmission (about 300 meters, while outdoor). Regardless of its small component count and 3V operating voltage that will easily penetrate the excess of some floors of an apartment development. It can be adjusted everywhere, while in the FM band (87-108MHz) and its transmissions can be picked up at any ordinary FM receiver. The coil (L1) should be about 3 mm in diameter, with five rounds of 0.61 mm copper wire. You are able Tx frequency range by simply adjusting the distance between the coils. The antenna should be half or quarter of an extended wave (100 MHz 150 cm or seventy-five centimeters).

FM wireless microphone circuit description: The audio amplifier stage (T1) is a conventional common emitter amplifier. The 47nF capacitor isolates the microphone from the base voltage to the transistor and only allows AC signals to pass. The LC tank circuit T2 occurs, the feedback capacitor C5 and the parallel LC circuit L1, C4. The coupling capacitor (C6) directs the signal to your amplifier RF (T3).

FM Wireless Microphone calibration circuit: Location of the transmitter 10 feet of a FM radio. Place the radio in a 89 to 90 MHz Spread the coil in the coil L1 frequency tuning also sought.

The heart of the circuit is 2SC1946A VHF RF power transistor. The transistor is specifically designed to operate at frequencies up to 175 MHz, with very good results.

The feedline is decoupled. The current amplifier can be more than 5 amps. All coils are made of 16gauge wire rod (copper or silver wire can do better) and HF RFC may be central torus (as shown in the image) or 6-hole ferrite R1 bead.C3 and snubber circuit forms, while R2 and C6 prevent the amplifier self-oscillation in VHF, it is sometimes necessary to add 180 ohms in parallel with the amplifier will L7.That to dispel UNDESIRABLE VHF thereby reduce the spurious level.

The 60Watts VHF power amplifier using the above circuit. 2SC1946A Two transistors are arranged at 90 degrees to each other and their results were combined using "Network Power Combiner". It is very difficult to combine skills in the VHF and UHF

Resistor R1 is a variable receiver to facilitate the adjustment process. The system works well when the circuit is ready. The first step is the optimization through the transmitter is turned on continuously, while the receiver R1 to set the value of being able to detect the signal from the transmitter. The second part is the receiver is controlled by LM 567. The following is a schematic drawing receptor.

In the image at the top of each channel is designed with a different frequency. Given the bandwidth of the frequency detection signal LM 567, between the frequencies on which they owe a big enough difference, let's try with a difference of 5 KHz.

This metal detector using CS209A made by Cherry Semiconductor. The CS209A is a bipolar monolithic integrated circuit for use in metal detection / proximity sensing applications.The CS209A metal detector IC has two on-chip regulators current, the oscillator and low-level feedback circuits, peak detection / demodulation circuit, a comparator and two complementary stages.The oscillator output, along with an external LC network provides controlled oscillations, where the amplitude is highly dependent the Q of the LC tank. The demodulator senses the negative peak of the oscillator wrap and provides a demodulated waveform as input to the comparator. The comparator sets the state of the complementary outputs by comparing the input of the demodulator to an internal reference.

The detector is a single coil 100uH. The IC has an oscillator integral part of the strangulation of an external LC circuit is the inductance that is changed by the proximity of metal objects. Is the change in the oscillation that is amplified and demodulated. LED 1 will light and the buzzer will sound when the inductance has changed. Installation is easy: R5 is adjusted with the LC away from any source of metal for the LED lights and buzzer. The control is reversed so that the LED turns off and stops ringing. When the shock comes in contact with a metal object that alters its inductance, LED and buzzer are activated.

The circuit diagram shown here is a simple circuit DC power delay, which is based on an SCR (Silicon-Controlled Rectifier). This circuit is very useful and can be used in many applications. The operation of this circuit is very simple. When input power is applied to the capacitor C2 charges through resistor R2 when the voltage on the capacitor just above the voltage of the Zener diodes D3 breaks, breaks and H1 SCR is triggered and the power delay will be available in late OUT.