Amplifiers

Hi,
I recently made an amplifier out of a lm386 ic. After making this I decided it was too staticy to use as an external speaker for my HF radio. Is there any way to make this less staticy. If not what type of IC would make a good replacement.

Pleeas post a schematic.

By staticy do you mean noisy? Lots of hiss.

The LM386 can be noisy if the gain is set too high, use a low noise pre-amplifier and set the gain on the LM386 to just 20 for low noise operation.

You could add a Notch Filter in to knock out background noise.

hotwaterwizard said:

You could add a Notch Filter in to knock out background noise.

Click to expand...

Except that's not a notch filter, it's a 'stop the speaker working' filter, blocking everything but the very high frequencies, and limiting those to 0.7V p-p.

A notch filter also wouldn't be any help reducing white noise.

hotwaterwizard said:

You could add a Notch Filter in to knock out background noise.

Click to expand...

Oh, my God!
Why don't you suggest a shortcut?
It makes even less noise

Oh good, I'm an electronics newbie and this had me very confused. I was thinking "wouldent that just short out the signal both ways? There must be some force at work here I've never heard of"

Maybe it is the radio that produces staticy sounds (that is what AM is for) and the amplifier just amplifies them.
Post the schematic of the LM386 amplifier that you made for us to see if its gain is too high.

schematic

I have a feeling that all the noise is because of my gain setting across pins 1 and 8.

Im sorry about the picture I was trying to draw it by memory at school and I got pins 5 and 6 mixed up.

Pin 5 is power in.

Pin 6 is output to speaker

Your circuit does not have pin 2 connected to 0V (ground).
It is missing a very important supply bypass capacitor. Use 100uF.
It is missing important parts at its output, a 0.047uF capacitor in series with a 10 ohm resistor at the output to 0V (ground).

These parts must be connected very close to the IC (on a pcb, not on a breadboard).

The resistor and capacitor at pin 5 and pin 8 increase the gain and increase the hiss a little.

You should always look at the datasheet for an IC to see which pin is which (you have them mixed up) and to see all the parts that are needed.