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