Circuitos_1
Circuitos_2

The circuit presented is a very popular circuit based on two IC 555’s. It produces a set of audible sounds that can be changed using the two potentiometers.

The original circuit was published by Forrest Mims in a book by Radio Shack “Engineer’s Mini-Notebook - 555 Circuits”.
It had the original name of “Sound Synthesizer” that was later changed to the one mentioned because of the similarity with the sound produced in the 80’s by the console Atari.
The circuit is an a-stable oscillator of a square wave that drives a monostable oscillator that creates a simple (square) pulse.
There are two controls, one for the oscillator frequency and one for the pulse length.

Schematic

Circuitos_3_Schematics

Bill of materials (BOM)

  • 2x NE555P (U1, U2)
  • 1x 1K Ohms Resistor (R1)
  • 1x 10nF Ceramic Capacitor (C1)
  • 1x 100nF Ceramic Capacitor (C2)
  • 1x 10uF Electrolytic Capacitor (C3)
  • 3x 500K Variable Resistor (VR1 a VR3)
  • 1x 9V Battery
  • 1x Battery cable

IC Pin-out

Circuitos_4_Pinout

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