•  
  •  

FM transmitter

Colpitts oscillator. Its frequency depends on the capacitance of the vary cap diode. The center frequency is changed by varying the biasing voltage of the vary cap through the 47K pot. You can use a 75cm telescopic antenna or simply a length of hook-up wire. Mine worked fine with a 6cm hook-up wire and gave a range of 100m with a good FM receiver. The approx. cost of the circuit is around Rs.35

Coil Details (Print on the PCB itself)

The coil shown below can be constructed on the PCB itself as PCB track. Just transfer the dimensions on a copper board and etch it. If the 1mm spacing is difficult use a sharp blade to remove unwanted copper.
You can also use a copper wire and construct a square spiral of the dimensions shown below. Please note that a small deviation from the given dimensions is permissible.
Note: You can even try a coil made of 18SWG copper wire of 5 turns and 5mm dia with air core. The center tap can then be taken at the 2nd or 3rd turn.( I have’nt tried it tell me if it works well)

coil

If there are any problems please contact webmaster@electronic-circuits-diagrams.com

Please share & like

Lot of 1323 ON Semiconductor NTMD4N03R2G MOSFET 30V 4A N-Channel T95082
$211.0 Lot of 1323 ON Semiconductor NTMD4N03R2G MOSFET 30V 4A N-Channel T95082 picture
Lot of 2500 ON Semiconductor NTMD4N03R2G, 137373 MOSFET 30V 4A N-Channel T95081
$399.0 Lot of 2500 ON Semiconductor NTMD4N03R2G, 137373 MOSFET 30V 4A N-Channel T95081 picture
Lot of 1445 ON Semiconductor MBRD835LT4G, 119795 Schottky Diode & Rectifier 8A 3
$289.0 Lot of 1445 ON Semiconductor MBRD835LT4G, 119795 Schottky Diode & Rectifier 8A 3 picture
Lot of 5000 ON Semiconductor 1SMA5941BT3G, 119796 Zener Diodes 47V 1.5W T95061
$399.0 Lot of 5000 ON Semiconductor 1SMA5941BT3G, 119796 Zener Diodes 47V 1.5W T95061 picture
Lot of 150 BSI Brilliance Semiconductor BS616LV4017EIP55 Power CMOS SRAM T94918
$275.0 Lot of 150 BSI Brilliance Semiconductor BS616LV4017EIP55 Power CMOS SRAM T94918 picture