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Fun Forty watts - My lm3886 DIY build.

Hiten

Active Member
Joined
Nov 24, 2019
Messages
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Location
India
Hello everyone,
I have very basic knowledge about electronics. This is my fun, getting hands dirty, Kill time during lockdown DIY. This is cheap money saving build (Cost me approx $ 90 Total). Sound is good and I enjoyed building it. Do suggest if any gross mistakes.

Sharing some pictures and details...
LM3886 A.jpg


LM3886 backpanel.jpg


LM3886 B.jpg


LM3886 innard 2.jpg

(1) Power on light and wire routing aluminum clips. (2) Extension shaft from robotics project. Brass piece was cut in half for two ends. (3) Main wire Terminal to distribute wires for fuses and transformer from AC mains. There is plastic film below PS boards. (4) 1.5A fuse for each channel. (Dont know if 1.5A is OK) Earlier I had two pole on/off switch but it broke so am temporarily using single pole switch (on live wire). Separate fuse on two PS board. There is also an extra third main fuse where mains wire comes in to the chassis.

LM3886 innard1.jpg

(5) Capacitor from Input ground to chassis to attenuate RF (6) Grommet from CD player mechanism. mains in has turntable grommet. Yes this is cheap build :) (7) power supply 0v two wires and mains earth wire grounded to Amplifier main chassis (8) Four 4700uf Caps. per channel. Silly me as space was congested I thought caps would get hot so removed original sleeves then put on new one realizing the outer capacitor case will be carrying voltages.

misc.jpg

(Top Left) Power on light plastic made from LED TV backlight bulb. (Top Right) 10 K volume pot made fake logarithmic with a resistor. (Bottom Left) Speaker Terminal. (Bottom Right) Aluminum piece is just for countersunk hole for screw.

Thanks for watching.
Regards.
 

Doodski

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Dec 9, 2019
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Hello everyone,
I have very basic knowledge about electronics. This is my fun, getting hands dirty, Kill time during lockdown DIY. This is cheap money saving build (Cost me approx $ 90 Total). Sound is good and I enjoyed building it. Do suggest if any gross mistakes.

Sharing some pictures and details...
View attachment 169045

View attachment 169046

View attachment 169047

View attachment 169048
(1) Power on light and wire routing aluminum clips. (2) Extension shaft from robotics project. Brass piece was cut in half for two ends. (3) Main wire Terminal to distribute wires for fuses and transformer from AC mains. There is plastic film below PS boards. (4) 1.5A fuse for each channel. (Dont know if 1.5A is OK) Earlier I had two pole on/off switch but it broke so am temporarily using single pole switch (on live wire). Separate fuse on two PS board. There is also an extra third main fuse where mains wire comes in to the chassis.

View attachment 169049
(5) Capacitor from Input ground to chassis to attenuate RF (6) Grommet from CD player mechanism. mains in has turntable grommet. Yes this is cheap build :) (7) power supply 0v two wires and mains earth wire grounded to Amplifier main chassis (8) Four 4700uf Caps. per channel. Silly me as space was congested I thought caps would get hot so removed original sleeves then put on new one realizing the outer capacitor case will be carrying voltages.

View attachment 169051
(Top Left) Power on light plastic made from LED TV backlight bulb. (Top Right) 10 K volume pot made fake logarithmic with a resistor. (Bottom Left) Speaker Terminal. (Bottom Right) Aluminum piece is just for countersunk hole for screw.

Thanks for watching.
Regards.
I love those heatsinks. They look like the Akasa brand.
 
OP
Hiten

Hiten

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Joined
Nov 24, 2019
Messages
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Location
India
Yes They are CPU heatsink. It had steel plate like this. Which was cut. The Aliminum protruding offset was filed off, and surface was smooth polished.
Looks nice. Good job.

I would reroute those two twisted pair wires so they don't pass through the heat sink fins.
Yes correct. wires were moved to take picture of volume control. They are floating in air away from the power supply wires as much as possible.
thanks and regards.
 

JayGilb

Addicted to Fun and Learning
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Jul 22, 2021
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Yes They are CPU heatsink. It had steel plate like this. Which was cut. The Aliminum protruding offset was filed off, and surface was smooth polished.

Yes correct. wires were moved to take picture of volume control. They are floating in air away from the power supply wires as much as possible.
thanks and regards.
I'm a huge advocate of reusing material in my builds. In this case, not only does it serve the requirements, it looks cool.
 
OP
Hiten

Hiten

Active Member
Joined
Nov 24, 2019
Messages
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Location
India
Hi all,
More fun added. As I had earlier built CNC Phono Preamplifier (DIYers popular phono preamp) which was lying around loose. I built a bypassable Tone control+Phono Preamp. Build cost around 65 US $.

Preamplifier 1.jpg

Some information about the build...
Preamplifier 3 copy.jpg

(1) Tone control board ready assembled bought from Amazon India (2) CNC Phono Power supply Built by me from kit (3) CNC Phono Preamp (4) RF Blocking capacitor
from common ground to chassis ground of all input (Tiny light brown thing) (5) Insulating sheet between board and metal chassis (6) Magnetic shield
(7) Individual Transformer for Phono preamp
Mains earth is connected to center of metal chassis (Paint removed) and 0v wire from both tone and phono PS is connected to it.
Preamplifier 4 copy.jpg

(8) Mechanical Selector switch (9) 6 Pin Tone defeat switch . As Tone preamp is always ON I Used 6 pin switch which lifts signal+ground wire for both channels when tone defeat switch is off (10) Power supply wire kept floated as below it are phono signal wires (11) Wire organiser to keep things neat..
The bunch of wires one sees is because I didnt had any shielded wire so from each input and each channel has separate twisted wire pair. so when tone preamp is off the ground remains separate for each channel. Tough I guess both channel ground if common will also be no problem.
Preamplifier 2.jpg

extra perspective
Preamplifier 5.jpg

Preamplifier and power amplifier.
Thanks for looking. Do suggest if there are any gross mistakes.
Regards
 
Last edited:

formula 977

Active Member
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Apr 8, 2022
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EI transformers, screws and nuts as stand-offs, panel mount jacks, twisted unshielded wire, a 1960's vibe happening on the front panels. Very nice looking stuff! This is real deal, old school DIY.
 
OP
Hiten

Hiten

Active Member
Joined
Nov 24, 2019
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Location
India
Excellent work. They are keepers for sure.
These will be sold to fund for my next build. (Probably 60~100w amp or speakers)
EI transformers, screws and nuts as stand-offs, panel mount jacks, twisted unshielded wire, a 1960's vibe happening on the front panels. Very nice looking stuff! This is real deal, old school DIY.
Main goal was to get hands dirty within budget as I build various things. Yes Old school way of doing things gives better longevity to products. My Philips Tube radio (Bought by my dad in 70s) is still working. Need few caps upgrade though.
regards
 
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