Amplifiers

Most of these are class D unless noted. I like class D most of the time.

National series

• LM386 noise outdated analog pretty cheap inefficient class AB but not really cheap compared to better newer amps
• LM4853 "Boomer" costs too much, love that product line name "Boomer" I mean ???
• LM48560 piezo / haptic driver

• TDA2005 -- I have a FutureKit that's been on my bench forever.

• TDA2050 high output obsolete class AB I got these on a whim but I need power supplies for them. Bench use??
• TDA2822 $4.5 obsolete
• TDA7266 7W+7W I have one around. It's compact. The heatsink is probably inadequate. The volume pot is funky. https://www.mpja.com/Adjustable-Stereo-Amplifier-Module-TDA7266/productinfo/31806%20MI/
• TPA2012 see adafruit
• TPA2016 has a control channel over i2c which is pretty neat, I think Adafruit has a breakout for it

There's a MAX58937 or something from Adafruit that has an i2s input instead of analog. It's around 3W

Another one I have is an Adafruit MAX9744 is a 20W stereo amp with their typically well-designed PCB. It has analog inputs (no i2s) Class D, designed for about 12VDC power, and has both analog and digital controls. (Volume and mute) so it would be good for a boom box for example. Mostly I think of the signal path being digital on the input side these days.

I have several i2s 20W boards including one in my junk box, I have 2 in service as media players with Pi Zeros called Okapi and Zebra. One is a HiFiBerry and another is a clone.

PAM amplifiers

Diodes Incorporated "PAM" series

• PAM8302 mono chip is around $.40 Adafruit breakout is $3.95, I have one I think

• PAM8403 very common very quiet but obsolete I have 2 from All Electronics; MPJA has them for $1.75 or get them on Amazon for cheaper
• PAM8406 upgrade to 8403 chip is $.84 and boards run around $1-$10 I ordered a couple spendy ones from Amazon, about $7 each

The PAM8403/PAM8406 has a mute control and PAM8406 has a mode control (Class AB or Class D) and a "shutdown" control and sometimes those pins are not brought out. The PAM8406 boards I bought today has a 2 gang volume knob and both those signals are available. I think mode, mute, and shutdown are usually tied to ground. Shutdown puts it in a uA mode and mute just stops output.

Read the design notes, they specify components to use to reduce clicks and pops. I doubt the $1 China boards pay much attention to that? The PAM8406 should have ferrites on the outputs. See the data sheet https://www.diodes.com/assets/Datasheets/PAM8406.pdf and eval board https://www.diodes.com/assets/Evaluation-Boards/PAM8406-User-Guide.pdf

SEARC CB project

CB = Cannon Beach. I prototyped amplifiers for Cannon Beach emcomm boxes, one with LM386 amps (too noisy) and one with the PAM8403 from All Electronics.

That one currently has two 10K pots to control volume on a headphone jack and on a speaker jack, the amp, a line level converter and an LM2940 voltage regulator. It takes the speaker out from a mobile radio, sends it through the level converter / impedance matcher, then into the volume pots, then into the 2 channel amp.

PAM8406

I set up an amp with a PAM8406 but was not impressed with the volume out so I will probably not use it. I should work on it a bit more, I used a switching regulator on it and maybe it's starved for current?? Don't know.