noise LM386 audio amplifier not amplifying

Posted on Feb 5, 2014

First I tried connecting the circuit to a 9V battery. (Multimeter reads around 8. 3 Volts, which is in the operating voltage range of the LM386 as per datasheet) The result I have is lots of noise, sometimes cracks and pops and a barely audible sound of the audio input (it feels like highly attenuated form of input which is very bad). It doesn`t ev

noise LM386 audio amplifier not amplifying
Click here to download the full size of the above Circuit.

en sound at least equal to the input! I want the gain to be around 200, so I do have a 10$mu$F capacitor across pins 1 and 8 of the LM386. I`ve also tried connecting to a 9. 6V - 250mA rated unregulated DC adapter. The results are almost the same. (though I seem to get a higher voltage here. ) Initially I simply used a in-ear earphone to pick up the mono output. I also tried connecting a small speaker (pictured). It`s apparently a 0. 2W 8$Omega$ speaker. The output is low, but the end result is similar to the earphone output. Here`s a snap of the breadboard. Sorry for the bad quality pic. This config used the DC adapter and a 0. 2W 40$Omega$ speaker. I even checked all parts for continuity using a multimeter. I`m also open to tips on troubleshooting this, since I`m new. Top bus is the Vs and the bottom bus is the common ground. Input audio is connected to the left end of the `green` 1k resistor. Its a very thin wire since its from a small 3. 5mm TRS cable. I don`t want anything super loud, just audible maybe like 2x of the input signal. If so, what kinds of speakers would this amp be capable of driving What would I need to make it sound acceptable Basically, what`s wrong with this circuit UPDATE: I followed all of your suggestions and my setup now consists of an additional 100$mu F$ capacitor in parallel to the power, a 100nF capacitor in series to the input audio signal and a 10$mu F$ capacitor connected to the bypass pin....

Leave Comment

characters left:

New Circuits



Popular Circuits

Mosfet Power Amplifier Circuit
A Compact Co-Planar Waveguide-Fed Zeroth-Order Resonant Antenna
Step Up PSU for LCD
System Modeler
Melody Generator Circuit using UM66
ADUC831 1.3MIPS 8052 MCU + 62kB Flash + 8-Ch 12-Bit ADC + Dual 12-Bit DAC
Telephone call meter using calculator & COB
OP113 wide range of precision temperature measurement circuit
PM4040F application circuit switching power supply drive
Electronic filter