2석FM송신기

두개의 트랜지스터로 만드는 FM송신기회로이며 콜피츠발진회로이다.ECM은 콘덴서마이크로폰을 가르킨다.

초단 트랜지스터의 1차는 오디오신호의 전력증폭용이고 2차는 고주파전력증폭용이다. 송신주파수 계산은 아래식과 같다. (영국UK FM방송대역구격)

http://www.zen22142.zen.co.uk/Analysis/colfr.htm

Using a circuit from the RF schematics section, and the formula from the theory section, you can estimate the resonant frequency for this oscillator:

Working out the parallel capacitance, C1 C2, (27*27)/(27+27) = 13.5pF
Assuming that the coil, L has an inductance of 0.2uH then:

= 96.8 MHz

This puts the frequency of oscillation in the middle of the UK FM Band (87.5 - 108 MHz). If an inductor with a core is used, then the oscillator can be tuned by moving the core. If an air spaced core is used, then tuning is achieved by physically squeezing or separating the turns.