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My lm386 isnt outputing any audio? Answered

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So basically I have decided to build a simple lm386 circuit. The only problem is no audio is coming from it i have tried using a new lm386, resistors, capacitors, power supply, and wires. I have even tried using a different breadboard. I tried at least 4 different lm386 schmeatics and none of them seem to work. The chip is receiving power but yet its still not working.

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petercdBest Answer (author)2014-01-24

I think you have killed the output with those bigass speakers, so first try something in the 8 ohm, 2W or less range.

Taken from http://www.electroschematics.com/552/lm386-audio-...

"The integrated chip LM386 is a low power audio frequency amplifier requiring a low level power supply (most often batteries)."

"The power output is around 550 mW at 16 ohm speaker impedance."

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steveastrouk (author)petercd2014-01-25

I don't think so. 2W is the power handling capacity of the speakers, if the amp hasn't got the oomph, it will shut down.

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Josehf Murchison (author)2014-01-24

Replacing the 10 k pot with a 10 k resistor has probably reduced you to minimum volume as much as the speakers need more power than the amp can supply.

I would suggest putting the 10 k pot in as in the schematic and using an earphone in place of the speakers.

As long as the LM386 IC is good it should work as designed.

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tramont (author)Josehf Murchison2014-01-24

Okey Dokey but one more question how can I determine the resistance of my pot? Also if I just decided to use the 4ohm 5 watt speaker would that be fine or would I need a 8 ohm speaker to be on the safe side?

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Josehf Murchison (author)tramont2014-01-24

Most pots have the value on them it will ether be marked 10 k or 103.

1 for first digit 0 for second digit and 3 for the multiplier just like color codes only numbers in place of colors 4R7 would be 4.7 ohm and 47R5 would be 47.5 ohm.

As for the 5 watt speaker it needs more power than your circuit can supply you need a 1/2 watt speaker for that amp. A cellphone speaker, an earphone, or a pizeo speaker.

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tramont (author)Josehf Murchison2014-01-25

I did exactly what you said got rid of the big speakers and found me a 8ohm 1/2 watt speaker (came out my clock :)) now the only problem is that the volume is low. I have everything turnt up to the max but still low. Heres a a video https://www.youtube.com/watch?v=aUfMgTto_Mc&feature=youtube_gdata_player

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Josehf Murchison (author)tramont2014-01-25

I watched the Youtube, that is working good.

Remember how the big speakers did not work at all, even at 1/2 watt it is still not very loud.

Your amp will never be very loud it is .35 watt and very loud systems are as high as 100 watts per channel.

However it is a good preamp and it is working as designed you may be able to get a better sound range with a 1/4 watt speaker but it wont be much louder. It is working right.

Now if you want louder, you have the preamp next build the amp try a AN7161 to AN7164N it will give you up to a 40 watt output with almost the same size circuit to add to that one.

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tramont (author)Josehf Murchison2014-01-25

I dont get how everyone eleses is louder than mine

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Josehf Murchison (author)tramont2014-01-25

What did they do that is different?

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tramont (author)Josehf Murchison2014-01-26

Absolutely nothing uhmm I do have one or the sides grounded on the pot

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Josehf Murchison (author)tramont2014-01-26

Something must be different.

Do you have a fresh IC maybe your larger speakers over taxed the IC.

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tramont (author)Josehf Murchison2014-01-27

Smh still no luck heres it on a pcb https://www.youtube.com/watch?v=5ec5aKA-XBc&feature=youtube_gdata_player also tge 8 ojm messed up so I went to this route

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tramont (author)tramont2014-01-25

Also im using 10k ohm pot i measured it with a multimeter and the max resistance was 8.50

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Josehf Murchison (author)tramont2014-01-25

I had to freeze the video isn't one side of that pot suppose to go to ground?

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petercd (author)2014-01-24

In the pic with the 9v batt it looks like you've crossed 1 leg of the i/p with 1 leg of the o/p. Maybe lift the batt so we can see whats going on with the wires underneath.

Is that a 10 ohm off pin 5 or 100 ohm? cos a 100 ohm would be too much, but a 10 ohm would work for speaker impedance matching in a pinch.

Just to recap, pin 5 is the o/p to speaker and the other speaker leg is the batt neg, which also goes to ground of ic( pin4) .

The inputs are pins 2 & 3, hard to see what you've done with the orange wire with black tape on it because you've cropped too much off the pic.

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tramont (author)petercd2014-01-24

Yeah on pin 5 thats a 10 ohm resistor. And on my pin 5 that orange wire is the speaker + and my pin 2 on my ic is grounded. Pin 3 i'm going to put a 10k ohm pot on it.

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FarmerKJS (author)2014-01-23

finnaly some one posts pictures on the first time!

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tramont (author)FarmerKJS2014-01-23

Lol yeah it only seems to make sense to post pictures. Do you have any suggestions?

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iceng (author)tramont2014-01-24

And good pictures with great focus.

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tramont (author)iceng2014-01-24

Thanks!!! Funny thing is i took it with my 5mp camera on my HTC I wasn't expecting for it to come out that focus and clear though.

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iceng (author)2014-01-23

looks wired correct

can't make out where 100k resistor goes

A 9v battery is not enough power for those speakers.

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tramont (author)iceng2014-01-24

Yeah I kinda figured that at first there were 8 aa batteries hook up to it producing 12v.

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steveastrouk (author)2014-01-24

Check things like power ON the pins of the chip with your meter. I hate breadboards like that, they are unreliable; its hard to say whether your CIRCUIT is at fault or the breadboard.

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tramont (author)steveastrouk2014-01-24

Yeah i'm starting to hear that breadboards aren't all that when it comes to building your circuit but at the same time I didnt want to put my circuit together on a pcb and run into problems such as this. Also i have a radioshack breadboard if that means anything.

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framistan (author)2014-01-24

I looked at your wiring real quick... Make sure you connected negative of the battery to the ground of the IC. It looks like negative of the battery might not be connected to the IC.

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tramont (author)framistan2014-01-24

Thanks for your answer!!! I have pin 2 & 4 grounded.

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Josehf Murchison (author)2014-01-24

One Look at the datasheet will give you your answer.

The power output is miles under what you need to drive the speakers.

The speakers are 10 and 5 watt the LM386 ICs output is .35 to .7 watt.

You can get the datasheet here:

http://www.maxim4u.com/

There just isn't enough power to run the speakers.

I would have compared your schematic with the examples in the datasheet but you didn't post your schematic.

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tramont (author)Josehf Murchison2014-01-24

Heres the schematic i used.

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iceng (author)tramont2014-01-24

I take it back it is a 10K resistor Brn-Blk-Org.

Are you using it as a replacement for a full-ON pot ?

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tramont (author)iceng2014-01-24

Yes but I just found a pot not sure ohm it is though.

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Josehf Murchison (author)tramont2014-01-24

That looks identical to the 200 gain in the datasheet.

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iceng (author)Josehf Murchison2014-01-24

Good point to join to my less important but still true lack of battery power for driving the

10 and 5 watt speakers.

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Josehf Murchison (author)iceng2014-01-24

It should work well as a preamp for a 15 watt amp.

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