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Author Topic: Feng - Mini Amp using PAM8403 (2x 3 Watt)  (Read 3638 times)

blackcorvo

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Feng - Mini Amp using PAM8403 (2x 3 Watt)
« on: April 14, 2016, 12:00:59 AM »
Recently I started working on a project that required a small, 5-volt stereo amplifier for sound, so I decided to buy a bunch of them to have a few spare ones in case anything caught fire or whatever.
After playing with one of them for a while, I decided to try and make a guitar amp out of it.

Here's the result:

Sample (Guitar: Vintage V100GT, bridge pickup)

Images of the test setup, schematic and (possible) layout in perfboard:

http://i.imgur.com/fiaXOBB.jpg
http://i.imgur.com/QOeLUjm.jpg
http://i.imgur.com/8pOCXgc.png

As funny as it may sound, the name came from me bashing my fingers on the keyboard after drawing the schematic, half-awake, at 4AM. It was not a joke about the power amp being from chinese manufacture at all.
« Last Edit: April 21, 2017, 01:44:24 PM by blackcorvo »

tonyharker

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Re: Feng - Mini Amp using PAM8403 (2x 3 Watt)
« Reply #1 on: April 14, 2016, 05:31:05 AM »
Does the TL072 work OK at 5v as the datasheet shows a minimum of about +/- 3.5v (7v total)? The TL062 would be better as this shows a supply of less than +/- 2v. The LM358P would also be suitable it has a minimum supply of +/- 1.5v.

blackcorvo

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Re: Feng - Mini Amp using PAM8403 (2x 3 Watt)
« Reply #2 on: April 14, 2016, 03:06:06 PM »
Does the TL072 work OK at 5v as the datasheet shows a minimum of about +/- 3.5v (7v total)? The TL062 would be better as this shows a supply of less than +/- 2v. The LM358P would also be suitable it has a minimum supply of +/- 1.5v.

I did not notice any problems with it working at 5v, but it's good to have other options. I simply used what I had in hands.
The worst that might be happening is that the TL072 is not as linear as it would be at 7v, but that isn't exactly a bad thing when it comes to guitar circuits.

J M Fahey

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Re: Feng - Mini Amp using PAM8403 (2x 3 Watt)
« Reply #3 on: April 15, 2016, 09:15:19 AM »
Cool project irmão  :dbtu:

That said, I'm also amazed that TL072 works at all with 5V ; TL062 is better suited and LM358 is *designed*  to work on 5V single supply as mentioned by tonyharker .

blackcorvo

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Re: Feng - Mini Amp using PAM8403 (2x 3 Watt)
« Reply #4 on: April 15, 2016, 11:20:17 AM »
Cool project irmão  :dbtu:

That said, I'm also amazed that TL072 works at all with 5V ; TL062 is better suited and LM358 is *designed*  to work on 5V single supply as mentioned by tonyharker .

The minimum voltage usually stands for the device working linearly. Not recommended for precision circuitry, but guitar preamps are much more forgiving.
I do not have a proper way to test how much the linearity changes, however.

Oooscar

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Re: Feng - Mini Amp using PAM8403 (2x 3 Watt)
« Reply #5 on: April 07, 2020, 03:59:57 AM »
This project looks interesting. The schematic shows more components than a typical op amp preamp. I am not taking into account the tone stack. Could it be simplified? For instance, could the 220 resistor be removed? Which function does it have?

Thank you very much.

P.S. That's my first post, btw.

willpirkle

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Re: Feng - Mini Amp using PAM8403 (2x 3 Watt)
« Reply #6 on: April 07, 2020, 06:37:55 PM »
Have a look at the NSC (now TI) “Boomer” series LM468x amplifiers. I worked on the test systems for those parts, and I could not believe how much useable power we wrenched out of +5V. We debuted them at an AES show, with a guitar “amp” we made with 4 of them (4W) all running on a 9V battery and VReg, inside of a little plastic box with belt clip. For a 5V platform, these were awesome. I think they still make a few of the models now, all smd tho.