Some ancient analog circuits are as popular today as when they were introduced decades ago. Often they easily beat micros and other digital circuit solutions in terms of basic simplicity. Forrest has done it again.. his favorite example is the Atari Punk Console.
The Atari Punk Console has become the popular name for a simple circuit that I first described as a "Sound Synthesizer" in Engineer's Notebook: Integrated Circuit Applications (1980) and then a "Stepped Tone Generator" in Engineer's Mini-Notebook: 555 Circuits (1984).
The circuit created a sequence of tones whose frequencies vary in distinct steps as a potentiometer was adjusted. Some in the electronic music community began experimenting with the circuit, and it is eventually labeled the Atari Punk Console by Kaustic Machines. "Atari Punk Console" yields 15,100 hits in a Google search. The circuit even has its own Wikipedia page.
Thanks to YouTube, you can check out some sounds from the Atari Punk Console from the comfort of your computer desk. For example, here is a version of the circuit built inside an Altoids box. Go here for a list of more than 200 video clips showing additional implementations of the Atari Punk Console.
Even older than the Atari Punk Console is the integrated circuit that makes it possible, the venerable 555 timer designed by Hans R. Camenzind for Signetics. The 555 was introduced in 1972 and continues to be one of the most popular integrated circuits ever designed.
Step 2: How It Works
The circuit for the Atari Punk Console is shown in Fig. 1. The circuit consists of a 556 dual-timer IC (equivalent to a pair of 555 timers) and half a dozen other parts.
In operation, the first timer is connected as an audio frequency oscillator and the second as a monostable multivibrator. The oscillator drives the monostable, which emits square output pulses with a duration controlled by R3. You have to actually hear the end result to fully appreciate the stepped tones that are generated as R1 and/or R3 are adjusted.
R1 controls the frequency of the audio oscillator. R2 controls the output pulse duration of the monostable multivibrator. R4 is an optional volume control that can be deleted by connecting the speaker directly to C3.
Step 3: Parts You Will Need
The following parts were used to assemble a breadboard version of the circuit:
IC1 - 556 dual timer IC (24329)
R1, R3 - 1 megohm trimmer pot (42981)
R2 - 1K resistor (661503 or similar)
R4 - 5K trimmer pot (optional volume control--not used in prototype version below) (182829)
C1 - 0.01 uF capacitor (15229 or similar)
C2 - 0.1 uF capacitor (33488 or similar)
C3 - 10 uF capacitor (545617 or similar)
SPKR - 4 or 8 ohm magnetic speaker (673766 or similar)
Miscellaneous: Perforated prototype board (e.g., Jameco 616622), 9-volt battery, battery connector clip (e.g., Jameco 216427), double-sided tape or 9-volt battery holder (105794), wire jumpers (e.g., Jameco JE10 Wire Jumper Kit; 19290).
Note: While the components listed above were used for the prototype, substitutions can be easily made. For example, you can alter the frequencies by increasing or decreasing the values of C1 and C2. Various small 8-ohm speakers can be used.
Prepare the Board and Install the Components
The circuit was assembled on a solderless breadboard and tested. When the circuit was operating properly, the components were transferred to a perforated prototype board (Jameco 616622) and soldered in place.
You can follow your own parts layout (or perhaps one of those shown on the web), and you might consider installing the circuit in a small enclosure. You can also substitute larger pots equipped with knobs so you can quickly alter the stepped tone output. Or you can simply copy the layout I used shown in Fig. 2 to make a trial version of the circuit.
Follow these steps to duplicate the prototype circuit shown in Fig. 2. The jumper leads correspond to the colors of those provided in the Jameco JE10 Wire Jumper Kit.
Be sure to work in a well ventilated room when using lead solder.
A complete Atari Punk Console Kit is also available at Jameco.
Step 4: Design Time
1. You can trim the perforated board now or after the components are soldered in place. The prototype board was cut along row 33, and the cut edge was filed smooth.
2. You will need to make a hole in the board for the battery clip leads. The hole for the prototype was made at hole D15 by carefully twisting an X-Acto knife through the hole until its diameter was enlarged to 1/8-inch (3mm). You can also use a drill.
3. Insert the 556 IC into the top side of the board (without the foil pattern) so that pin 1 is in hole A14 (second A...B...C... series) and pin 8 is in hole U17. (Figure 3 shows the 556 pin outline. You can see the board's hole numbers by turning the board over to see the foil traces.) Secure the 556 in place with a piece of tape, flip the board over and solder all 14 pins to their respective foil patterns. You can, of course, install the 556 elsewhere on the board. Just be sure that all the pins of the 556 are inserted into their own foil patterns.
Figure 2. Parts layout for an assembled version of the Atari Punk Console.
Figure 3. Pin outline for 556 dual timer.
4. Insert a bare jumper wire between 556 pins 12 and 13 and solder in place.
5. Insert a yellow jumper wire between 556 pins 2 and 6 and solder in place.
6. Insert a yellow jumper wire between 556 pins 10 and 14 and solder in place.
7. Insert a blue jumper wire between 556 pins 5 and 8 and solder in place.
8. Insert a blue jumper wire between 556 pins 4 and 14 and solder in place.
9. Bend one lead of R2 against itself and insert the leads between 556 pins 1 and 2 and solder in place.
10. Insert R1 so that an outer pin is in the same foil trace as pin 1 of the 556 and solder the outer and center pins in place.
11. Insert a gray jumper wire between the center terminal of R1 and 556 pin 4.
12. Insert R3 so that an outer pin and the center pin are across the foil traces for 556 pins 13 and 14 and solder in place.
13. Insert C1 across 556 pins 6 and 7 and solder in place.
14. Insert C2 across 556 pins 7 and 12 and solder in place. If C2 is polarized, the plus (+) lead goes to pin 12.
15. Insert the minus (-) lead of C3 in the same foil trace as pin 9 of the 556 and solder in place.
16. The plus (+) lead of C3 is connected to optional volume control R4 (see Fig. 1) or directly to one of the speaker terminals. (R4 is not used in the assembled circuit shown in Fig. 2, but you can insert it now or later if the circuit's sound is too loud.) After you decide where to install the speaker (see step 17), insert the plus (+) lead of C3 where it will share a common foil trace with one of the two speaker wires.
17. After you decide where to install the speaker (see step 17), connect a red jumper wire between pin 4 of the 556 and a common foil trace where the second speaker wire will be soldered.
18. If you use the speaker shown in Fig. 2 and listed in the Parts List, you will need to connect connection leads to its terminals. The small, bare, U-shaped jumper wire in the Jameco JE10 Wire Jumper Kit works well. Invert the speaker and insert one end of a jumper through one of the speaker terminals. Hold the emerging length of the jumper with long-nose pliers and solder the "U" portion of the jumper to the speaker terminal. Be sure to pull upward on the wire so that it will extend outward from the speaker. Repeat this procedure for the second speaker terminal. Finally, insert the two connection leads you've added into appropriate holes in the board that match up with steps 15-16.
19. Insert the battery clip leads through the top side of the board and tie them into a knot on the foil side of the board. Leave plenty of length on the top side of the board.
20. Flip the board over and solder the red battery clip lead to any of the wires emerging from the foil trace connected to 556 pin 14.
21. Solder the black battery clip lead to any of the wires emerging from the foil trace connected to 556 pin 7.
22. Put on some safety glasses and clip off all the excess wire lengths emerging from the back side of the circuit board.
23. When the circuit is finalized, attach the battery to the board using double-sided tape or a 9-volt battery holder (see parts list).
Step 5: Testing the Circuit & Going Further
Use a small screwdriver to rotate the rotors of both R1 and R3 to their midpoints. Connect a fresh 9-volt battery to the connector clip. The speaker will probably emit a tone. If not, try rotating R1's rotor. If no tone is emitted, remove the battery and carefully check your wiring.
When the speaker is emitting a tone, you're ready to experiment.
This circuit is easily modified by substituting various kinds of variable resistors for R1 and R3. For serious electronic sound effect applications, consider installing the circuit board in a small enclosure and replacing the two trimmer pots with full size pots equipped with knobs. Or dispense with the pots altogether by soldering a couple of cadmium sulfide photoresistors (Jameco 202454 or similar) across both R1 and R3 to transform the circuit into a light-sensitive tone stepper that you can "play" simply by waving your hands over the photocells to alter the light striking them, hence their resistances.
According to the Atari Punk Console Wikipedia page, some people have installed their version of the circuit in various novelty housings, including an old Atari mouse or joystick.
Have fun and be sure to post your experiences with the Atari Punk Console at one of the sites that describe it.