Did I make the cheapest DIY amplifier?

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6 layer PCB FAB+Assembly - ONLY $2! :jlcpcb.com/?fr...
I wanted to make a cheap DIY amplifier, so I found the cheapest amplifier IC and built an audio amp around it. Could this be the cheapest DIY amplifier you can make? The final price will surprise you!
My homemade amplifier is based around the FM8002A chip, which costs just 4 cents apiece. Since it is an SMD component, the chip needs a printed circuit board to work, so I designed one and had it manufactured by JLCPCB.
I gathered the rest of the components from LCSC.com and assembled the amplifier by hand using my soldering station. Soldering SMD components seems challenging at first, but it is really not if you are patient and use parts that are large enough.
The result: after a few tweaks to the design, I had a great-sounding, albeit low-power audio amplifier that cost well below a dollar to put together. Thanks for watching!
🛒 Shopping links*:
🟢 Parts for the amp: LCSC.com
🟢 The soldering iron I use: amzn.to/3PHuoiy
🟢 The oscilloscope I use: amzn.to/3J71k02
🟢 OLFA cutting mat: amzn.to/3HX3Ipp
🟢 OLFA cutting knife: amzn.to/3wgmUMu
🟢 Mini Breadboards:
Amazon US: amzn.to/3vvFtfC
AliExpress: bit.ly/brdbd1
🟢 Helping Hands:
Amazon US: amzn.to/4bmrbxx
AliExpress: bit.ly/3yo2wKd
🟢 Ceramic tweezers:
Amazon US: amzn.to/4bN4thF
AliExpress: bit.ly/3zUrVGG
🟢 3.5mm audio breakout:
Amazon US: amzn.to/3V36ilb
AliExpress: bit.ly/3UItDr0
🟢 SMD to breadboard adapter:
Amazon US: amzn.to/3URbBTs
AliExpress: bit.ly/415zQPr
🟢 The wireless microphone I use: amzn.to/4bGMnPh
*Affiliate links. The price you pay DOES NOT CHANGE, but I may make a small commission if you make a purchase. Your support helps me make more videos. Thanks!
#electronics #amplifier #pcb #diy
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Опубликовано:

7 сен 2024

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Комментарии : 24

@LeftyMaker 3 месяца назад

Let me know if you think I could have made it cheaper :D (Links to parts and tools are in the video description)

@marcdraco2189 Месяц назад

The gain is a negative feedback loop following a simple inverting amplifier. The input impedance is 20K with a 0.39 uF cap giving 3dB point of (checks calculator) of almost 20Hz on the button. I'd say they're dreaming. :) Could probably push that to at least 100-200Hz without really noticing much of an issue unless you're driving a set of cans. The gain in their schematic is -2 (-1 * 20/20) but the upper limit is determined by the input level - a quieter source needs more gain so a volume control ahead of the gain stage would be a smart move. With 80K you'd have a gain of -5. The open loop gain is probably in 80dB or more even with a simple design. Negative feedback (and lots of it) lowers both noise and distortion which is why it sounds good. Thanks Harald!

@Donkey1793 3 месяца назад

Hi ! Really cool project :) I try to use less and less Tantalum capacitors because of the Tantalum extraction procedures and their high cost. It would be interesting to know the effect of replacing the 1uF Tantalum capacitor with a ceramic one ! Good job again :)

@LeftyMaker 3 месяца назад

Hmm, never considered this about tantalum. I can probably test what happens if I replace it with a ceramic one

@marcdraco2189 Месяц назад

They are awful for audio too. Film where possible, NP0 where space is at premium.

@bob_mosavo 3 месяца назад

Thanks 👍

@crazyfurnaceguy1229 3 месяца назад

Use 4ohm speaker instead of 8ohm speaker , it can up to 2 watts output but recommend electrolytic cap on power rail for peak output current (if insufficient current condition)

@Gunbudder 3 месяца назад

i'd love to know how long it lasts under load! i recently bought a very VERY cheap amp built almost exactly like this one, and it lasted about 2 hours of normal use before it died completely. looks like the chip itself failed internally

@LeftyMaker 3 месяца назад

I've had them on at full power for a few minutes at a time and I've been playing with them for about a week. No failures so far, but if anything changes, I'll post here

@questionman5 3 месяца назад

Cool video! Per the Analog article, it would be interesting to know if tapping on the cap would introduce any signal from the vibration. Also curious, for JLC boards, how did you split them apart? Never ordered a panelized board.

@LeftyMaker 3 месяца назад

I can try tapping on it and see what happens. About the boards, there is a "Panelize" option in EasyEDA. You just specify how many copies you want and that is it

@burtburtist 3 месяца назад

Very good!

@SianaGearz 3 месяца назад

These have made their rounds on cheap Bluetooth speaker boards, i've seen this chip. Mhm thanks to SD feature, i might even find a use for it, but realistically i probably want a PAM8302A instead. Or Fuman's own TC6805.

@LeftyMaker 3 месяца назад

Yup, both chips look interesting. Might try them too some day. I wonder how they make a profit. They cost pennies

@SianaGearz 3 месяца назад

@@LeftyMaker I think they have a scheme, i don't think it's your typical profit oriented operation. Numerous grants from the People's Republic have been issued which have a strategic purpose to move semiconductor manufacturing inland and secure vital capability, and at some point a decade and a half ago simple linear-function and analogue switching ICs were a very important milestone, you start with low value products to be able to achieve higher value ones, now there are different more complex milestones to hit. Who knows they might have fabbed a billion chips because they could do this on public funds and are perhaps now just slowly selling them off. Also once you already have capacity to make linear ICs or somesuch, you're best off just letting it go brrrr no matter if it's technically losing money, because the secondary costs and externalities of shutting down the manufacturing may be higher. I'd love some sort of expert investigation into this, but a lot of these things particularly in China are anything but transparent.

@daisymo2959 3 месяца назад

Wow !

@SattarM-ju3dv 3 месяца назад

I'm not expert in this field or not other electronics world, but I like this Chanel are values for everyone, I falls in love with.... Tribute

@Velocity_AU 3 месяца назад

This is pretty damn cool, I wonder how does it compare to an amp thats say 10 dollars? How much does price improve sound?

@LeftyMaker 3 месяца назад

for 10$ you can buy something that can realistically put out 10 watts, so the biggest difference will be the output power and thus volume (which for many people means quality too :D I assume the fidelity will be better too, yet that's a bit more difficult to measure and appreciate

@Velocity_AU 3 месяца назад

@LeftyMaker would something that's $10 be comparable in size as well as quality I wonder. I might need to try making one myself at some point