Author Topic: 1W Portable FM Transmitter problems  (Read 86 times)


  • Guest 1W Portable FM Transmitter problems
« on: April 11, 2018, 09:06:22 pm »
I have built the 1W FM transmitter from your site ( At first, I couldn't get the 2SC1971, co I replaced it with the RD06HVF1, without making any other modifications to the circuit.
When I turned the transmitter on, the PLL LED lit up and after adjusting the volume knobs I could transmit music from my computer for about a minute, after that it drowned in static. However, the 6 V / 0,1 A bulb wouldn't light up at all and the RD06HVF1 wouldn't even get warm, even though I set the transmitter to HI. I tried messing around with the controls, held down the PLL reset button (at least I think that's what it is) for about ten seconds and then *POOF*, the LED stopped working and there was no signal coming out.

So I started to replace parts, got my hands on some 2SC1971 to make the circuit exactly like in the instructions, and finally, I replaced the PIC microcontroller. The LED is now on, but I still get no FM signal, no matter what frequency I set and the bulb still has not even once turned on.

This is my first electronic circuit, so all the knowledge I have comes from building it and some youtube videos about the basics of electronics. I don't really know where to start troubleshooting  :-[. Am I supposed to calculate voltages in different parts of the circuit and then measure them? If so, how? Or is there some easier way?

Thanks a bunch in advance for helping me out. It would be greatly appreciated  :)


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Re: 1W Portable FM Transmitter problems
« Reply #1 on: May 09, 2018, 08:42:43 pm »
rd06hvf1 is a mosfet transistor and need some gate voltage about 5v and it is not as an npn rar to find c1971 but some people here will try to help you in the power section
for other stage keep only the bfr96 first one and reburn the pic and stresh the coil of the oscillator so it must work .Blind way i cant help you more so please upload some close pictures of the transmitter
what kind of varicap u use