Altoids Tin Speaker

Step 2 Schematic and PCB Layout

As noted in the introduction, the circuitry surrounding the Maxim MAX 756 and LM386 chips is directly from their respective datasheets. The schematic and the PCB were designed using the freeware version of the EAGLE Layout Editor from CadSoft.

Comments

[PazzoPazzo]

(removed by author or community request)

[Delta25]

is needed the 9 volt imput or you only need de AA battery?

[chicken12175]

is there any way i can use an LM311 chip as the amplifier. can you do a schematic for this chip please as this is the only chip i can get easily. BTW great guide!

[matth3w]

I haven't had experience using the LM311 chip, but a quick survey suggests it's really a comparator and not an amplifier. I would recommend sticking with the LM386-3 (more powerful than the LM386-1) because I know it works :-). The online electronics supply companies will accept small orders, so the parts should be available (I suppose this depends on where in the world you live). Good luck sourcing parts.

[chicken12175]

OK
cheers for the advice and will try to get an LM386 chip

[AKninja04]

Why do you wire the input coming from the audio jack to the negative input on the lm386 instead of the positive?

[AKninja04]

Also, where do all of those grounds connect back to? Sorry if these are very novice questions.

[matth3w]

I followed the schematic for the Crackerbox Amp to determine the connections to the LM386. I don't think it matters which input you use. I also think it made the layout slightly easier, but I could be misremembering. The grounds connect back to the battery ground. Look closely at the constructed board for the green wire jumpers. I think one goes from the LM386 area back the the power area. I had to use them because I etched my own board and couldn't make it double sided. This may make it look like there is not a connection back, but there is.