I just built the FM radio circuit here and after a fashion i got it working, the problem is it is EXTREMELY quiet audio to the point i had to put the speaker on my ear to hear anything.

Has anybody built or have a known working circuit i can try that gives a reasonable output?

I have found some on a google search but i am aware that there is a lot of garbage posted online that just doesn't work, so if anyone has a known working circuit, that would be great.

I don't know if the low output of the circuit i built was down to the radio receiver section or the amplifier section.

 

That will be a poor FM (regen) receiver under the best conditions.
Post a picture of what you built. With the antenna.

 

That will be a poor FM (regen) receiver under the best conditions.
Post a picture of what you built. With the antenna.

I have taken it apart to reuse the parts....sorry i don't have any pics of it.

 

Output of the LM386 must be terminated with a proper R-C network , read the data sheet.

 

Output of the LM386 must be terminated with a proper R-C network , read the data sheet.

I checked the data sheet and i had the resistor and capacitor switched around with the resistor connected to pin 5 and then the capacitor going to ground, might this have been why the output was so quiet?

 

I checked the data sheet and i had the resistor and capacitor switched around with the resistor connected to pin 5 and then the capacitor going to ground, might this have been why the output was so quiet?

If two devices are connected in series and nothing else connected at the junction then it makes no difference which one comes first.

 

I mentioned this only because the posted circuit doesn’t show the resistor in series with the capacitor.
But if you actually included it in your prototype, then it is fine.

 

I mentioned this only because the posted circuit doesn’t show the resistor in series with the capacitor.
But if you actually included it in your prototype, then it is fine.

Yes i added it but like i said i had reversed the resistor and capacitor although Mr Chips said that doesn't matter, i also added a 0.1 uf across the supply rail directly on the supply pins of the IC and that stopped the oscillations i was getting on the output.

 

I'm going to rebuild my radio circuit but i'm going to replace the audio amp section with this circuit, does anyone know if C6 is in the right place?.... seems to me that it will have no effect?

https://www.circuitbasics.com/build-a-great-sounding-audio-amplifier-with-bass-boost-from-the-lm386/

 

In the URL you reference, the author talks about placing C6 between the positive input and ground, which is pin 3, but shows it connected to pin 2. So yes, it's doing nothing as shown, and needs to be moved.

 

I have taken it apart to reuse the parts....sorry i don't have any pics of it.

"I just built the FM radio circuit" and the next day you've taken it apart after having issues.

Glad to see you're rebuilding it for us. Some pictures of the new build please.

Documentation is the key here. Your physical build is the documentation we need to give good answers to the question. Only showing us a decades old schematic really doesn't' help.

 

Do you know what level of signal i should be seeing on the base of Q2?

 

The best way to use an LM386 in your application is to use the datasheet schematic called "Amplifier with Gain = 200", which is reproduced here:

https://www.homemade-circuits.com/ic-lm-386-datasheet-explained-in-simple/

The only thing missing is power supply decoupling, which is the best part of the 2nd schematic in post #9.

ak