My question is if I build this simple AM receiver and feed the output to the LM386 using a gain of 50, should the output to the speaker be good quality audio?
I saw the datasheet for the LM386 and it shows an "AM Radio Power Amplifier" schematic, but can I use one of the other setups without having to add the "ferrite bead" etc... ?
My question is if I build this simple AM receiver and feed the output to the LM386 using a gain of 50, should the output to the speaker be good quality audio?
I saw the datasheet for the LM386 and it shows an "AM Radio Power Amplifier" schematic, but can I use one of the other setups without having to add the "ferrite bead" etc... ?
Well you don't get 'good quality audio' from AM, but using the LM386 will give the quality you expect from AM radio. Depending on the output level from the radio section you might not need as much gain? - and don't worry about ferrite beads!.
I built the AM receiver circuit and fed the output to the "'AM Radio Power Amplifier" on the LM386 datasheet. I have everything hooked up except I am not using "ferrite beads" on the output of the LM386.
I actually get a Radio Station around 900AM, but the sound is VERY VERY VERY low!!!
I have the IC at a gain of 50 but I have ti put my ear right next to the speaker to hear it. I tried increasing the gain to 200 but no luck.
Is there anything else I can do to increase the volume?Huh
You forgot to say that the collector voltage of your receiver's Q3 is way too low, like you said on the other web-forum. It should be easy to fix.
The "radio" is a very poor design. Its text says it is a regenerative receiver. Regenerative uses positive AC feedback. This "radio" has negative DC feedback and doesn't have an AM detector nor an RF filter.
Hi Nigel,
The LM386 IC amp has plenty of gain at AM radio RF frequencies. The ferrite bead on the output wire and twisting the wires etc stops it from radiating RF back to the radio's input.
I am using a transistor from a pack of common NPN-Type switching transistors. I do not have the exact model. The are probably like the MPS2222A transistors.
I swapped out the transistor for another one and got the same voltage readings and same results to the speaker.
You say the design uses positive AC feedback but the radio gives of negative DC feedback. Is there any simple way to fix this? I get a weak signal, I just need it to be louder.
Do you have a schematic for another AM receiver you would suggest?
I stopped listening to the very poor sound quality of AM radio in about 1960 when I heard the fantastic excellent sound quality of FM radio.
AM radio is garbage! Static, interference, narrow audio bandwidth and very high distortion.
Hi Crivoli,
If you fix the "Q3 is saturated" problem in the lousy AM receiver circuit you have, then it might work a little better than now.
The collector voltage of Q3 will be about 0.1V if the collector resistor's value is much higher than 10k, or if the 560k resistor to its base connects to +9V instead of to its collector.
Hi Nigel,
The LM386 IC amp has plenty of gain at AM radio RF frequencies. The ferrite bead on the output wire and twisting the wires etc stops it from radiating RF back to the radio's input.