That is a easy and small Two Transistors FM Transmitter. It is right for ready espionage for the strip from radio fm or receiver of vhf. Of route, the leisure purpose also exists and the youngsters will adore having a transmitter that allows speakme for a radio fm located at a distant region and like this pretend the spy. Two transistors fm transmitter
operation of the 2 transistors fm transmitter
the voice/song captured via the electric microphone, your voice or near people’s chats, are mischievous to the bottom of the pnp transistor q1 through c1 (10uf) wherein is amplified. The resistor r2 collectively with r3 it determines this amplification.
After having amplified,
the sign is eliminated from the collector of q1 transistor and mischievous to the base of q2 transistor (npn), where it modulates in frequency the signal generated by means of this stage. This stage is an oscillator of high frequency that operates within the strip of fm. Your frequency is decided by way of l1 (0. 3uh) and for the adjustment at the variable capacitor (cv). The received signs, already modulated in frequency, are mischievous to a linked antenna within the collector of the transistor q2 (bc557 transistor).
The range of the transmitter relies upon in this antenna,
of the feeding of the circuit, and of the place in which it is operating. Within the open field, with a 6 v battery and an antenna of about 40 cm of period, this variety of this tow transistors fm transmitter may be a thousand meters. With a smaller antenna, the variety of this transistor will lessen. A not unusual wall isn’t always an impediment for this transmitter.
Circuit two transistors fm transmitter
additives
transistors:
q1 – bc557
q2 – bf494
mic–microphone electret terminals
resistors: (1/4 w, five%)
r1–4,7 kΩ
r2–220 kΩ
r3–22 kΩ
r4–10 kΩ
r5–6,8 okayΩ
r6–47 Ω
capacitors:
c1–10 µf/sixteen v – electrolytic
c2–four,7 µf/16 v – electrolytic
c3–10 nf – ceramic
c4–4,7 pf – ceramic
c5–one hundred nf – ceramic
cv–trimmer from 3-30 to 5-50 pf
different elements:
l1 – 0. 3uh
b1 –3 to 9 v
ant –antenna
published circuit board with full detail is given beneath