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lm386_amplifier

Title: Build an LM386 Amplifier

Class Size: 5

Cost: $20 (estimated)

Pre-requisites: none

Minimum Age: XX and up (under 18 must have parent present)

Learn to solder an LM386 amplifier.

Order of Build:

  • Resistors
    • 1K (brown-black-red)
    • 4.7k (yellow-violet-red)
  • IC socket
    • Orientation isn't critical, but should be observed
    • Note that pin 7 doesn't have a solder pad. No need to solder it.
  • Ceramic capacitors (C1 & C4, both 0.1 uF)
    • No orientation
  • 3.5mm jack
  • External connection pins
    • A+/A- (audio input?)
    • +/- (power) (if using a 9V clip, just solder the clip directly instead of pins, but you'll want to hot glue some strain relief because it will fail eventually, otherwise)
    • S+/S- (speaker)
    • Cut the pairs of pins off of the 6-pin strip
    • Solder in one pin, adjust fit if necessary, and then solder in the other.
  • LED (D1)
    • Long lead toward the triangle, short lead toward the line
  • Power jack (J3)
    • Solder one pin, adjust, solder the other two
  • It may be in your best interests to insert the LM386 into the IC socket at this point. The caps & pot make it difficult to insert if present.
  • Electrolytic capacitors
    • Long lead positive.
  • Potentiometer
    • Cut off the anti-rotation tab
    • Solder one pin, adjust, solder the other two.
  • Speaker
    • Use two headered wires. cut off headers at one end, and strip the remainder
    • Solder stripped wires to tabs on speaker
    • Insert header pins into S+ & S-

Options/Hacks:

  • External speaker (i.e. a cabinet or something)
    • Wire up header wires to a 1/4“ jack instead of the speaker
  • Additional gain
    • Simple way: wire up a capacitor between pins 1 & 8 of the LM386
    • adjustable way: wire up a 5k potentiometer between pins 1 & 8
  • Power switch
    • Wire up SPST switch between power source and + on PCB
lm386_amplifier.txt · Last modified: 2017/12/02 15:05 by sdh7