Paper Mosquito Heart

The NE556 Atari Punk Console as a heart-shaped paper circuit · By Onion Madder · Mess O' Pedals

The Paper Mosquito, redrawn as a heart. The board is four sheets of paper thick: a blank sheet folded and glued into a core, with the printed sheet folded around it. A 1N5817 diode means a battery clipped on backwards does nothing instead of cooking the chip, an LED tells you it is on, and the battery snap solders straight to the board.

I kept the volume pot. It is not great at the extremes, but I think it is part of what gives the first one its fuzzy, ethereal sound. Pitch and shape are both B500K, the same as the one I built.

⚠ Before you start tap to expand / collapse

Paper burns. Keep the iron moving, quick joints, and don't rest it on the sheet. Work over something that isn't flammable, and keep a damp sponge handy.

Socket the chip. Soldering straight to the NE556 means holding heat on paper right next to 14 tightly packed holes. The socket takes the heat instead, and the chip goes in last.

Bare traces on the back can short. The only place they run close is trace G under the socket, so keep it centered between the two rows of pins.

Loud and shrill. It's still an APC. Start with VOLUME low.

What you'll need

tap to expand / collapse

New to the parts? Each line notes how to spot it - the printed marking, the package, or the polarity clue.

1× NE556 dual timer and a 14-pin DIP socket - spot it: NE556 printed on top; a notch or dot marks pin 1. The socket is what saves the paper from chip-pin heat.
2× B500K pots (pitch and shape) - spot it: marked B500K; B = linear taper, and the middle lug is the wiper (a B1M works too, just a wider range)
1× B10K pot (volume) - spot it: marked B10K (B5K is fine)
1× 1N5817 Schottky diode (D1) - spot it: small black body; the gray or silver band marks the cathode
1× LED, any color, and a 2.2K resistor (R3) - spot it: the LED's long leg is +, the flat side of the rim is −; 2.2K is red-red-red (1K is brighter and drains the battery faster)
2× 1K resistors (R1, R2) - spot it: bands brown-black-red; non-polar
2× 0.01 µF ceramic (C1, C2) - spot it: tiny disc printed 103
1× 0.1 µF ceramic (C4) - spot it: disc printed 104
1× 10 µF electrolytic (C3) - spot it: a little can; the stripe marks the minus leg, and the long leg is plus
Bare tinned wire for the traces on the back, and insulated wire, white and yellow (J1 and J2 are white, J3 is yellow)
An SPST toggle, a battery snap, a jack or an 8 Ω speaker, and a 9V battery or at least two vape cells in series
A second sheet of plain printer paper, a glue stick, and an awl - the blank sheet becomes the core, and any sharp point works in place of an awl

Quick reference - the chip and the traces

Parts go in from the printed front, so the socket on the front reads exactly like this map. On the back it's mirrored, which is why the back heart prints pin numbers next to every hole.

╭───∪───╮ DIS A ┤ 1 14 ├ V+ (VCC) THR A ┤ 2 13 ├ DIS B CTL A ┤ 3 12 ├ THR B RST A ┤ 4 11 ├ CTL B OUT A ┤ 5 10 ├ RST B TRG A ┤ 6 9 ├ OUT B GND ┤ 7 8 ├ TRG B ╰───────╯

Power corner

D1: band toward the bus, away from SW
S: D1·a → SW
A, V+ bus: D1·k → R3·a → R1·a → R2·a, with B from pin 14
L: R3·b → LED·+; E: LED·− → BAT−

Around the socket

J1, white: pin 4 → pin 14; J2, white: pin 10 → pin 14
J3, yellow: pin 5 → pin 8
N: pin 13 → pin 12
G: pin 2 → pin 6, down the middle of the socket

The two timers

D: R1·b → pin 1, with PITCH E; F: PITCH W → pin 2
H: C1·a → pin 6
P: SHAPE E → R2·b; O: SHAPE W → C2·a → pin 12
C: C4·a → pin 10; K: C4·b and C2·b → J

Ground and output

I, ground bus: BAT− → C1·b → J (from pin 7)
Q: pin 9 → C3·+; R: C3·− → VOLUME IN
T: VOLUME G → bus; U: VOLUME W → OUT
M: OUT-G → bus

Reading the sheet

The fold sheet: two hearts side by side, joined along a short pink FOLD line. The left heart, FRONT - parts side, draws each part where it sits: the D1 1N5817 diode, R3 2.2K and the LED in the top left corner beside ringed SW, BAT+ and BAT- holes, R1 and R2 1K above the NE556 socket in the middle, which has its notch labeled and pins 1 to 14 numbered, C1, C2, C4 and the 10 microfarad C3 around the chip, PITCH B500K at the left, SHAPE B500K at the right and VOLUME B10K at the bottom with IN, W and G holes above it, ringed OUT-G and OUT holes either side of it, and the title Paper Mosquito by Onion Madder in the right lobe. Faint dashed gray lines preview the connections. The right heart, BACK - solder side, is the mirror image with bold black traces tagged with pink letters, a V+ bus dipping under the heart's top notch, a ground bus following the left curve around to the bottom, and short gray and yellow arcs for the insulated wires at the socket. — Page 1 of the build sheet: front heart on the left, back heart on the right, folded around the core along the pink line.

Front: each part is drawn where it sits, with its value printed next to it. The faint dashed lines are only a preview of what connects on the back, so you can see where a part goes without flipping the board. The five ringed holes are for wires going off the board: BAT+ and BAT− for the battery, SW for the toggle's return, OUT and OUT-G for the jack. PITCH and SHAPE have three holes each: E (an end lug), W (the wiper, its middle lug) and X (the other end, left empty). VOLUME uses all three: IN, W and G.

Back: every bold black line is a trace you make with bare wire or a bent part leg, tagged with a pink letter so the steps can name it. The dashed gray and yellow arcs are the three insulated wires. Small pink numbers beside the socket holes are the chip's pin numbers.

Steps 1–11 Print, fold, glue, poke

The sheet is the circuit board, and it's four sheets of paper thick. A plain sheet folded in half and glued to itself makes the core, then the printed hearts fold around the core and glue on, one heart on each face. The back heart is a mirror image of the front, so once it's folded the holes line up on both faces.

Print at 100% / "Actual size". Fit-to-page shrinks it and the socket holes stop matching the chip.

Print, fold, glue, poke
Step	Do
1	Print page 1 on plain printer paper at 100% / Actual size.
2	Measure the 100 mm bar at the top right of the sheet. If it isn't 100 mm, fix the print scale and print again.
3	Fold a second, blank sheet of printer paper in half.
4	Glue-stick the whole inside of the blank sheet, close it, and press it flat. That's the core: two sheets thick.
5	Fold the printed sheet along the FOLD line, printing on the outside, so the two hearts sit back to back.
6	Unfold it again and glue-stick the back of the FRONT heart.
7	Press the core onto the glued back of the FRONT heart.
8	Glue-stick the back of the BACK heart, fold it over onto the other face of the core, and press it flat. Now it's four sheets thick.
9	Let the glue set for a few minutes, then cut along the heart outline through all four layers. Don't cut across the FOLD hinge.
10	Poke the 14 U1 holes from the front with an awl or other sharp point, straight down through all four layers.
11	Poke the other 32 dots the same way. Check the back and open any hole that didn't come all the way through.

Steps 12–19 Start in the middle: the socket

Everything builds outward from the chip. Each part goes in from the printed front, then on the back you bend its legs along its trace to the socket pin it belongs to and solder it there. Every part you add is anchored to the middle, so the whole thing gets stiffer as you go instead of floppier.

Quick dabs only. Paper scorches if you sit on it: touch, flow, lift.

Start in the middle: the socket
Step	Do
12	Push the 14-pin socket into the U1 holes from the front, notch toward the top edge (the drawn notch).
13	On the back, bend socket pins 1, 7, 8 and 14 outward slightly so the socket can't fall out.
14	Insulated white wire J1 from socket pin 4 to socket pin 14. Solder at pin 4 only.
15	Insulated white wire J2 from socket pin 10 to socket pin 14. Solder both wires at pin 14 together, then J2 at pin 10.
16	Insulated yellow wire J3 from socket pin 5 to socket pin 8. Solder at both pins.
17	Trace N: short bare wire from socket pin 13 to pin 12. Solder at both pins.
18	Trace G: bare wire from socket pin 2 down the middle of the socket to pin 6, centered between the two rows of pins. Solder at pin 2 and pin 6.
19	Trace J: bare wire from socket pin 7 down to the ground-bus line. Solder at pin 7 only; the far end gets soldered with the bus.

Steps 20–28 Next ring out: the caps

The three small caps sit right beside the chip. Each one goes in from the front, and on the back one leg bends along its trace to a socket pin.

Leave the legs long until each one is soldered, then snip the tail.

Next ring out: the caps
Step	Do
20	C4, 0.1 µF (marked 104): legs into C4·a and C4·b from the front.
21	On the back, bend C4·a's leg along trace C to socket pin 10. Solder at C4·a and at pin 10.
22	Bend C4·b's leg along trace K until it crosses trace J. Solder at C4·b and where it touches J.
23	C2, 0.01 µF (marked 103): legs into C2·a and C2·b from the front.
24	On the back, bend C2·a's leg along trace O to socket pin 12. Solder at C2·a and at pin 12.
25	Bend C2·b's leg along trace K to C4·b. Solder at C2·b and at C4·b.
26	C1, 0.01 µF (marked 103): legs into C1·a and C1·b from the front.
27	On the back, bend C1·a's leg along trace H to socket pin 6. Solder at C1·a and at pin 6.
28	Solder C1·b's leg in its hole and leave the tail long. The ground bus lands on it later.

Steps 29–35 Out to the resistors and the output cap

Same move, one ring further out. The resistor legs are long enough to reach their traces on their own.

Out to the resistors and the output cap
Step	Do
29	R1, 1K (brown-black-red): legs into R1·a and R1·b from the front.
30	On the back, bend R1·b's leg along trace D to socket pin 1. Solder at R1·b and at pin 1.
31	R2, 1K: lies sideways. Legs into R2·a and R2·b from the front.
32	On the back, bend R2·b's leg down trace P to its corner. Solder at R2·b only; the shape pot joins it later.
33	C3, 10 µF electrolytic: long + leg into C3·+, striped leg into C3·−, from the front. Lay the can flat over its drawing.
34	Trace Q: bare wire from socket pin 9 along the line to C3·+. Solder at pin 9 and at C3·+.
35	Bend C3·−'s leg along trace R so its end sits over the VOLUME IN hole. Solder at C3·− only; the volume pot joins it later.

Steps 36–41 Power corner: diode and LED

The top corner is the power entry. D1 is a 1N5817 that only lets current through one way, so a battery clipped on backwards just does nothing instead of cooking the chip. R3 and the LED tell you the board is on.

D1's band is the side current leaves from. It points toward the bus, away from the SW pad. Backwards, the whole board stays dead.

Power corner: diode and LED
Step	Do
36	D1, 1N5817: band end into D1·k, plain end into D1·a, from the front.
37	Trace S: on the back, bend D1·a's leg along the line to the SW pad. Solder at D1·a and at SW.
38	R3, 2.2K (red-red-red): legs into R3·a and R3·b from the front.
39	LED: long leg into LED·+, short leg (flat side of the rim) into LED·−, from the front.
40	Trace L: on the back, bend R3·b's leg along the line to LED·+. Solder at R3·b and at LED·+.
41	Trace E: bend LED·−'s leg along the line to the BAT− pad. Solder at LED·− and at BAT−.

Steps 42–44 The two buses

Power dips under the heart's top notch, ground follows the left curve around to the bottom. Each one is a single bare wire, soldered wherever a part or trace meets it.

The two buses
Step	Do
42	Trace B: bare wire from socket pin 14 straight up to the V+ bus line. Solder at pin 14.
43	Trace A, V+ bus: bare wire from D1·k through R3·a, down the line, then across through R1·a to R2·a. Solder at D1·k, at R3·a, at R1·a, where it meets trace B, and at R2·a.
44	Trace I, ground bus: bare wire from the BAT− pad, around the left curve, then along the bottom line to where it meets trace J. Solder at C1·b and at J; the BAT− end is already soldered.

Steps 45–56 The pots, outermost

The pots go in last because they're the heaviest. Push each pot's lugs through from the front, shaft up, middle lug (the wiper) in W. With solder-lug pots, solder a short wire to each lug and push the wires through instead.

The pots, outermost
Step	Do
45	PITCH pot, B500K: lugs into the PITCH holes E, W and X.
46	Trace F: bare wire from PITCH W to socket pin 2. Solder at W and at pin 2.
47	Trace D: bare wire from PITCH E along the line to R1·b. Solder at E and at R1·b. X stays empty.
48	SHAPE pot, B500K: lugs into the SHAPE holes E, W and X.
49	Trace O: bare wire from SHAPE W to C2·a. Solder at W and at C2·a.
50	Trace P: bare wire from SHAPE E to the corner of R2's leg. Solder at E and where it touches R2's leg. X stays empty.
51	VOLUME pot, B10K: lugs into the VOLUME holes IN, W and G.
52	Solder VOLUME IN, where C3·−'s leg is already sitting.
53	Trace T: bare wire from VOLUME G straight up to the ground bus, where trace J meets it. Solder at G and at the bus.
54	Trace U: bare wire from VOLUME W down and across to the OUT hole. Solder at W and at OUT.
55	Trace M: bare wire from the OUT-G hole up to the ground bus. Solder at OUT-G and at the bus.
56	Snip every leg tail that sticks past its joint.

Steps 57–62 Off the board

The battery clips straight onto the board, and the toggle hangs off two pads on flying leads so it can go wherever your enclosure wants it. Solder each wire on the back.

Leave the battery unclipped until the meter checks.

Off the board
Step	Do
57	Battery snap red (+) to the BAT+ pad.
58	Battery snap black (−) to the BAT− pad.
59	A wire from the BAT+ pad to one lug of the SPST toggle.
60	A wire from the other toggle lug to the SW pad.
61	Jack tip (or speaker +) to the OUT hole.
62	Jack sleeve (or speaker −) to the OUT-G hole.

Steps 63–67 Check, then chip

Meter it before the chip goes in. If the socket is happy, the chip will be too.

Check, then chip
Step	Do
63	Clip the battery on, toggle on, socket empty. The LED should light.
64	Meter socket pin 14 to pin 7: battery voltage minus about 0.3 V (the diode's drop).
65	Meter pin 4 to pin 7, then pin 10 to pin 7: same reading as pin 14 both times.
66	Toggle off. Push the NE556 into the socket, notch toward the top.
67	Toggle on with VOLUME low. It should drone right away. Sweep PITCH, then SHAPE.

⚠ If it won't sing

Voltage check
Meter between	Expect (socket empty, toggle on, LED lit)
BAT+ pad → BAT− pad	battery voltage (9V, or 7.4V on two vape cells)
Socket pin 14 → pin 7	battery voltage minus about 0.3 V
Socket pin 4 → pin 7, pin 10 → pin 7	same as pin 14 (the resets)
Socket pin 5 → pin 8, with the meter on continuity	beep (J3)

Troubleshooting
Symptom	Check
LED off, board dead	D1 in backwards (band must face the bus), battery snap reversed (D1 blocks it, nothing gets hurt), or the toggle wires not on BAT+ and SW.
LED on, but silent	First turn VOLUME up. Then J1 and J2: pins 4 and 10 must read battery voltage. Then J3, then pin 14 and pin 7.
Silent, chip warm	Two bare traces touching on the back, most likely trace G brushing a pin. Hold the heart up to a light and look at the back under the socket.
Faint, or only a tick	C3 the wrong way around (+ goes in C3·+), or C1/C2 not reaching ground through traces I/K.
LED on but dim, or flickers with the sound	Normal-ish on a tired battery. A fresh 9V fixes it.
Putt-putt motorboating	C4 not soldered at both ends, or a cold joint on trace C or K.
A pot does nothing at one end	Normal: that is the 1K stopping it at zero. Does nothing at all: lug in the wrong hole, or the wiper isn't in W.
Paper scorched or a hole tore	Glue a scrap of paper over the back, re-poke, carry on. It is paper.

Things to try

Body contacts: solder a bare-wire staple onto trace D and another onto trace F, a few millimeters apart on the front. A fingertip across them bridges the pitch pot, so you play pitch by touch (works best with PITCH turned toward its slow end). An LDR across the same two points makes it follow light.
CV inputs: pins 3 and 11 are left open, like the Mosquito. A 100K from either into a jack gives you the CV inputs from the Mosquito page.
One and a half: hang an NE555 one-shot off pin 5 for the “one and a half” mod. Draw its traces onto your sheet in pen first.
Color the front in. Blasser's sheets are half schematic, half drawing, and nothing on the front side carries current.

The APC descends from Forrest M. Mims III's “Stepped Tone Generator.” The paper-circuit method is Peter Blasser's / Ciat-Lonbarde's. This layout and the words are my own.