Malzeme Listesi: All resistors are 1/4 watt 5% R1,R2,R8 = 1K C1 = 1uF/63V, electrolytic R3 = 100K C2,C3 = 10nF, ceramic R4 = 150K C4,C5,C9 = 4.7uF/63V, electrolytic R5,R7 = 10K C6,C12,C13,C14 = 1nF, ceramic R6 = 220 ohm C7,C8,C11 = 5pF, ceramic R9 = 10 ohm C10 = 220uF/63V, electrolytic P1 = 5K trimpot Q1,Q2 = 2N3904 L1 = 3.9uH Q3,Q4 = 7001, NTE123AP L2 = 1uH D1 = 1N4002 L3 = aircoil, 8.5 turns air space 1/4 inch diameter Devre Notları: This circuit provides an FM modulated signal with an output power of around 500mW. The input microphone pre-amp is built around a couple of 2N3904 transistors (Q1/Q2), and audio gain is limited by the 5k preset trim potentiometer. The oscillator is a Colpitts stage, frequency of oscillation governed by the tank circuit made from two 5pF ceramic capacitors and the L2 inductor. Frequency is around 100Mhz with values shown. Audio modulation is fed into the tank circuit via the 5p capacitor, the 10k resistor and 1N4002 controlling the amount of modulation. The oscillator output is fed into the 3.9uH inductor (L1) which will have a high impedance at RF frequencies. The output stage operates as a 'Class D' amplifier, no direct bias is applied but the RF signal developed across the 3.9uH inductor is sufficient to drive this stage. The emitter resistor and 1k base resistor prevent instability and thermal runaway in this stage.