This circuit is used to Modify an Acoustic into the electric guitar on FM wireless transmitter system. It is small, cheap, easy to build.
The acoustic guitar pickup of this circuit like working of the condenser microphone. Which is good because This system has less distortion than the general guitar pickup, that include of magnets and coils, may be hard to find and expensive.
The 88 MHz FM transmitter circuit can be listened to with the standard FM radio. This frequency is determined the value of L1 and capacitance between the plate-P1 and guitar strings that is connected to ground through crimping terminal,the capacitance is about 5 pF.
Figure 1 the circuit diagram
When strum Guitar strings to make the capacitance changes. And we connect P1 to L1 as the frequency generator circuit will be FM modulation, send to broadcast transmission on the FM radio.
How to builds
We should assemble the circuit into a small metal box that can Tighten the nut mounted CRIMPING TERMINAL fit. And a metal box with a ground circuit. Connecting cable from P1 should be as short as possible. (See in Figure 2)
Figure 2 How to install the circuit on the guitar.
The parts you need
Q1____2SC1815____0.4A 40V NPN transistors
C1____0.01uF 50V Ceramic capacitor
C2____0.005uF 50V “_________”
R1____100K____0.25W Resistors tolerance: 5%
B1_____9V battery and snap connector
L1_____Coil 5 turns of 28 AWG with a inside diameter of about 0.25 inch.
The plate is made from thin sheets of aluminum, Wide and 1 cm, length 8 cm. Placed under the guitar strings is about 2 mm.
Adjustment and usage
First of all, adjust frequency of the FM radio to 88 MHz, then stretch-shrink L1 while slowly play the guitar until hear a sound on radio. Then close the lid for good, tune the radio to hear a bit more clear as possible, it can play.
If created have problems “wave away”, To cutting thin metal cover plate over the guitar strings from P1 until carton circuit. Then fastened to the box lid, to solve the wave crashes. Periodic spread spectrum of about 20 meters.