Veronica 1W FM transmitter is an easy to build transmitter. Veronica is also known for frequency stability, clean FM signal and uses no integrated circuit. The Veronica oscillator is actually formed from 2 oscillators which operates somewhere around 50 MHz in anti phase and the 2 signals are combined to form 100MHz FM radio signal. This kind of circuit design is stable and is amplified up to 1W by 2n4427 transistor. Veronica transmitter is equipped with a mini-mixer and so you may forget an external mixer. This consist from T1 transistor which amplifies the microphone signal before it is combined with CD player audio or PC signal. R1 and R2 are potentiometers (variable resistors) used to adjust the audio level. The component between R8 and C21 represents the oscillator which generates radio signal. D1 is a varicap diode (like a variable capacitor or trimmer) controlled by audio signal. C12, C13 and L1 determines the frequency.
Veronica components list
R1+2 10k pot
C1, 2, 7, 16, 17, 19,
24, 29 & 31 1n
C3-5 & 8 10u elect.
C6, 18 & 30 220u elect.
C9, 10 & 20 10n
C13 22p trimmer
C14 & 15 15p*
C21, C25 & 26 65p trimmer
C27 & 28 1.8p
L1 – 6 coils / 2 turns, 5mm diam si 5mm length
L2 – 3 turns, 7mm diam si 7mm length
L3 – 4 turns, 5mm diam si 7mm length
L4 – 6 turns, 5mm diam si 10mm length
D4 Standard LED
The transmitter must be mounted in an aluminium carcase connected to ground. The power supply voltage is between 9 and 16V, at 16V the rf output power is 1W and at 12V is 600mW and at 9V is 200mW.