Begin this week I created a simple Audio Amplifier with the LM386 (see previous entry). I noted that there was some noise coming from the speakers. I already had a 100uF capacitor on the breadboard to smoothen the power fluctuations. I searched the internet for solutions to further reduce the noise. I found three possible measures.
- Connect a 10uF to pin 7 of the LM386. In the schematics from HackaweekTV pin 7 (bypass) is not connected. On the website Learning About Electronics I found a tip to connect 10uF capacitor to this pin and ground it. Here is a link.
- On a another blog (Low Voltage. Mostly Harmless…) a 10nF capacitor is added to pin 6 and ground. Here is a link to this article.
- This is a feedback the LM386 output (pin 5) and pin 8. The feedback includes a 10k resistor and a 10nF capacitor in series. I found this tip here.
For a video that demonstrates the Audio Amplifier see below.
|Original ‘noisy’ circuit.|
|Improved circuit with significantly reduced noise. The 10uF capacitor between pin1 and 8 is removed. I didn’t need the additional gain.|