Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Created small amplifier- Circuit cuts out after short period of time.

Status
Not open for further replies.

CorySCline

New Member
Hello. I created a small circuit using LM386N-4. It plays music, however after a short period of time, it cuts off sound and I need to turn it off and back on to get it to play again. The louder i turn up the source (MP3 Player), the quicker it happens. How can i track down the issue?
 
Is the LM386N mounted on a heat sink? If not it's likely overheating and shutting itself off to avoid blowing. Put you finger on the device when it is playing loudly and you'll likely detect the source of the problem. ;)
 
Post a schematic of your circuit. Are you talking about a time of seconds or minutes before it cuts out?

ken
 
Sounds like a dodgy electrolytic capacitor, or poor connection (dry joint) to a cap.
 
Sounds like a dodgy electrolytic capacitor, or poor connection (dry joint) to a cap.

I agree, he should replace any filter cap (perhaps with a larger value) and should check the output filter capacitor. We won't know for sure untill we can see the schematic.
 
Last edited:
A dead battery has a fairly high voltage until it drives the amplifier then its voltage drops until the amplifier doesn't work anymore.
Give the dead battery a rest for a couple of minutes then it can repeat playing then cutting off.
 
This is the diagram I have used.
 

Attachments

  • Parts-and-schematic.jpg
    Parts-and-schematic.jpg
    15.3 KB · Views: 144
Your circuit is missing a 47nF capacitor (or 0.05uF) in series with a 10 ohm resistor from the output to ground. They prevent the amplifier from oscillating and are shown on ALL schematics on its datasheet.
 

Attachments

  • LM386 power amplifier.PNG
    LM386 power amplifier.PNG
    28.8 KB · Views: 136
Your circuit is missing a 47nF capacitor (or 0.05uF) in series with a 10 ohm resistor from the output to ground. They prevent the amplifier from oscillating and are shown on ALL schematics on its datasheet.

Yea, see this is why I call this process learning lol. This was my first project in this area EVER and I was just building from repetition more than knowledge. I have learned a lot along the way and I went ahead and built the circuit according to the +50 gain datasheet. Go figure it works lol. Thank you all for your time. :)

This was an initial "Proof of concept" I guess I would call it. I would like to tackle a full tube Amp if its feasible. (Mind you I understand there is A LOT of learning involved :) ) Can anyone point me towards reliable resources to start such a project? As you can see, my original resource wasnt so hot lol....
 
In addition to what AG said, you may want to add a 10k resistor to ground from the negative lead of C1, you can also try removing the capacitor completely. Try adding a 10k volume knob (a 10k pot with the whiper going to the input, one lead to ground and one lead to the negative terminal of C1). If you add said volume control, you won't need the 10k resistor to ground.
 
The 10k resistor to ground at the input is not needed since the LM386 already has a 50k resistor there.
The 4.7uF polarized capacitor for C1 is stupid because it causes the low frequencies to roll off below 1Hz!
A 330nF (0.33uF) non-polarized film capacitor passes frequencies above 10Hz.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top