Hello,

You say you are powering the circuit with 3.6 Volts.
The datasheet explicitly states that a voltage over 3.5 Volts may damage the chip:



Put a diode in series with the power supply and see what happens.

Bertus

 

Hello,

You say you are powering the circuit with 3.6 Volts.
The datasheet explicitly states that a voltage over 3.5 Volts may damage the chip:

View attachment 120454

Put a diode in series with the power supply and see what happens.

Bertus[/QUOTE
tried discharging my lithium ion battery a bit to decrease its voltage to 3.4V..Still no change.

 

Also wanted to ask this. In my previous attempt making this circuit, when I used 1% Metal film resistors instead of carbon film ones, the static was much greater. I had placed them close to each other and vertically. Now you all are saying to clip the legs. I wanted to know if placed horizontally, will it be better to use those metal film resistors again. Needless to say, they are mentioned on the circuit providing website. What should I do?

 

All right..So I made the PCB version of this circuit using Metal Film Resistors and I'm facing the same problem here. Please help!

 

Hello,

Did you lower the supply voltage with the diode I mentioned?
The static might come from erratic behaviour due to the to high voltage.

Bertus

 

All right..So I made the PCB version of this circuit using Metal Film Resistors and I'm facing the same problem here. Please help!

Does your PCB copy the original layout?

 

Hello,

Did you lower the supply voltage with the diode I mentioned?
The static might come from erratic behaviour due to the to high voltage.

Bertus

Which diode should I use. Zener or 1N4007?

 

Does your PCB copy the original layout?

Yes, It does copy the original layout, except L1 has been substituded by a and a varicap.

 

Hello,

Just try a 1N4007 in series with the powersupply.
This will drop 0.5 - 0.7 Volts, so the voltage will be in range.

Bertus

 

Hello,

Just try a 1N4007 in series with the powersupply.
This will drop 0.5 - 0.7 Volts, so the voltage will be in range.

Bertus

ok ..so you're only using it as as a voltage reducer. Also, about using a high Q coil, I have 3 values, 7uH,15uH and 100uH. There's also 150uH. Which one should I use?

 

Yes, It does copy the original layout, except L1 has been substituded by a and a varicap.

Varicaps can cause the kind of disrortion you described if the RF voltage waveform across it is large enough to cause a significant change in capacitance.

You might want to test for this by temporarily replacing L1 with a hand wound inductor that you can adjust by complessing and spreading it and changing the varicap to a fixed capacitor.

 

Good idea......you could use popsicle sticks to adjust the coil, while watching on a SDR.

 

Varicaps can cause the kind of disrortion you described if the RF voltage waveform across it is large enough to cause a significant change in capacitance.

You might want to test for this by temporarily replacing L1 with a hand wound inductor that you can adjust by complessing and spreading it and changing the varicap to a fixed capacitor.

I have been using it. Was successful in finding the transmission frequency by lengthening or shortening it. But even after setting an ideal length of coil for required frequency, the song is transmitted so badly that it is beyond recognition.

 

Do you mean that there is no varicap in the circuit now? If there is no varicap and you still have the problem, then it is agreed the varicap is not the source of the problem.

 

Do you mean that there is no varicap in the circuit now? If there is no varicap and you still have the problem, then it is agreed the varicap is not the source of the problem.

yes, i tried doing it. the varicap isn't the problem.

 

yes the varicap isn't the problem

Can I suggest that you stop calling the trimmer capacitor which you are using a 'varicap'. To folk on here 'varicap' means a semiconductor diode used as a variable capacitor by varying the reverse voltage across it.

 

Can I suggest that you stop calling the trimmer capacitor which you are using a 'varicap'. To folk on here 'varicap' means a semiconductor diode used as a variable capacitor by varying the reverse voltage across it.

ok...then trimmer capacitor it is

 

So after a lot of googling, I found this schematic.
https://elect.wikispaces.com/Low+power+FM+stereo+transmitter
The quality is good now, but I am not getting the "Stereo Effect" in its transmission. Also, what I am observing is that the transmission volume is low and the left channel's audio is being loudly transmitted in both channels on the receiver side while the right channel is lowly transmitted in both channels.
I checked the channels using this video:

Also, just so you know I am still using my lithium battery currently at 3.4V, so I have not used the power circuit as shown on the schematic of the link I provided.
So, now my final aim is to increase transmission volume and get a true stereo output.