Descripción de Wireless microphones - Design and Circuitry:

Wireless microphones - Design and Circuitry A wireless microphone includes a microphone itself which is generally of a capacitor or electret type; an audio converter, a radio transmitter, an antenna and a power supply. Wireless microphones operate by way of coding an audio signal which is converted into a radio signal and transmitted at certain frequencies to the receiving base, a radio receiver or a UHF tuner. The method of audio transmission using wireless microphones has enjoyed great popularity at the wireless technology market for long. The wireless microphone's block diagram is as follows: A radio transmitter includes a microphone amplifier with an automatic signal level control, a modulator, a master self-oscillator, a power amplifier, a matching device, and a power supply. A transmitting antenna is connected to the output while the microphone is connected to the input. Such a block diagram requires transistors with minimum saturation voltage. This improves the performance of low-voltage power supplies, the performance index and the transmitter's output power. The cutoff frequency of transistors should correspond to the operating frequency of the selected receiving range to ensure high performance of the transmitter. Small components used in the device help to minimize the size of the wireless microphone. From the point of view of circuitry, wireless microphones of primitive design look as follows: There is a wireless microphone working within the range from FM88 to 108 megahertz. The high-frequency oscillator includes two transistors to increase the output power. This device is equipped with a high-sensitive microphone MKE-3. Take a look at one more simple circuit working at the same range. It offers a smooth operating frequency tuning within the range using a miniature variable capacitor connected to the oscillator circuit. The reach area of a wireless microphone embraces several dozens of meters. These wireless microphones work within broadcasting UHF/FM ranges. They are very convenient as transmitted signals can be received by regular radio receivers working within respective ranges.