Simple Wireless Microphone. Basics of Circuit ...

Simple Wireless Microphone. Basics of Circuit DesignSmall and medium power radio transmitters are quite popular within the range of electronic devices. These devices are usually used in assemblies and components based on bipolar and field-effect transistors.Radio transmitting devices are quite complex to make and configure, as the main range of accessories has variations in settings, fairly minor but noticeable.The category of radio transmitting consumer household appliances includes various low-power radio stations, wireless microphones, alarm systems with remote listening.At this stage of electronics development special chips which enable building of miniature transmitters are used for building circuits of radio transmitting devices. But anyway a separate category of devices is running on transistors and the flawless operation in amateur designs justifies their use.Simple circuits of transmitting devices enable beginner electronic engineers to make a particular design themselves.Thus, here is a simple circuit of a home wireless microphone.The design does not contain any expensive components, moreover, their number is minimal. In the first place the microphone itself is a common electret microphone. The root of the circuit is a bipolar domestic transistor KT3107 with a maximum cut-off frequency of 200MHz. Then there are only two resistors and three miniature condensers. Don't be limited by dimensions. The important thing is to understand the operational principle of the microphone and its design features.The coil is wound with a wire of 0.5 mm on the mandrel, with 6 turns.A small piece of wire, about 40 cm, is used for the antenna, it can be in the form of a helix.The microphone works in FM-band of 88-108MHz. Although the range is only several meters, but it is sufficient for its direct purpose as a common but not a wireless microphone.