Build guide

Laser Tripwire

15×29 @ 2.54mm pitch · 14 components · 22 wires

1. Prepare

Verify component pinouts against each manufacturer’s datasheet before wiring. Label cut wires with their wire numbers; the same numbers follow them through every stage. Wire colors are written out for black-and-white printing. Custom colors can be named in the wire library.

Progress is saved on this browser for this board revision. Changes to the board or measurements start a new checklist. Printed diagrams are references, not life-size templates.

22 wires to prepare; 517mm total wire, including end allowances.

Parts List

13 unique parts

Ref DesPartValueManufacturerPart NumberQtyLink
C1Ceramic Cap100nF——1Amazon
C2Ceramic Cap1uF——1Amazon
J1Power Input (2-pin)——1—
LED1, LED2LED——2Amazon
Q1Potentiometer——1—
R1Resistor (axial)1k——1Amazon
R2Resistor (axial)100k——1Amazon
R3Resistor (axial)560——1Amazon
R4Resistor (axial)680——1Amazon
U1Photoresistor (LDR)——1—
U2DIP-8——1—
U3Tactile Button 6mm——1—
U4Piezo Buzzer——1—

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2. Cut wires

Cutting quantities by color and length

22 wires · +5mm per end for lead-through

Cut#NetColorRouteCut LengthBends
18GNDBlackC22 → E2523mm13mm (90°)
6ARMBlackE15 → H1128mm15mm (90°)
12VCCBlackG15 → K1228mm15mm (90°)
11VCCBlueD12 → F1417mm—
17GNDBlueD21 → D1720mm—
5SENSEBlueG9 → I1535mm8mm (90°), 23mm (90°)
4SENSEGreenG7 → I715mm—
22GNDGreenK6 → I518mm10mm (90°)
10VCCGreenB6 → B1225mm—
16VCCGreenH3 → M630mm18mm (90°)
1TRIMRedD10 → D815mm—
13VCCRedC5 → H523mm—
19GNDRedF17 → F1223mm—
7ALARMRedE23 → J2528mm18mm (90°)
21GNDWhiteL7 → L813mm—
3REDWhiteL27 → L2418mm—
15VCCWhiteJ20 → L2323mm10mm (90°)
9ALARMWhiteM18 → I1138mm23mm (90°)
2GREENYellowE27 → E2418mm—
20GNDYellowG11 → K823mm16mm (45°)
8ALARMYellowL25 → L1925mm—
14VCCYellowJ11 → K1933mm8mm (90°)

Total wire: 517mm (20.4in)

3. Bend wires

Use the straight-line ruler to mark bend points on the wire before bending. Use the bent shape as a visual reference while bending.

Bend ruler and shape for wire 1
Cut 15mm.
Bend ruler and shape for wire 2
Cut 18mm.
Bend ruler and shape for wire 3
Cut 18mm.
Bend ruler and shape for wire 4
Cut 15mm.
Bend ruler and shape for wire 5
Cut 35mm. Bend 90° down at 8mm. Bend 90° right at 23mm.
Bend ruler and shape for wire 6
Cut 28mm. Bend 90° right at 15mm.
Bend ruler and shape for wire 7
Cut 28mm. Bend 90° down at 18mm.
Bend ruler and shape for wire 8
Cut 25mm.
Bend ruler and shape for wire 9
Cut 38mm. Bend 90° left at 23mm.
Bend ruler and shape for wire 10
Cut 25mm.
Bend ruler and shape for wire 11
Cut 17mm.
Bend ruler and shape for wire 12
Cut 28mm. Bend 90° up at 15mm.
Bend ruler and shape for wire 13
Cut 23mm.
Bend ruler and shape for wire 14
Cut 33mm. Bend 90° down at 8mm.
Bend ruler and shape for wire 15
Cut 23mm. Bend 90° down at 10mm.
Bend ruler and shape for wire 16
Cut 30mm. Bend 90° down at 18mm.
Bend ruler and shape for wire 17
Cut 20mm.
Bend ruler and shape for wire 18
Cut 23mm. Bend 90° right at 13mm.
Bend ruler and shape for wire 19
Cut 23mm.
Bend ruler and shape for wire 20
Cut 23mm. Bend 45° right at 16mm.
Bend ruler and shape for wire 21
Cut 13mm.
Bend ruler and shape for wire 22
Cut 18mm. Bend 90° up at 10mm.

4. Place wires

Component side. Select a wire to emphasize its route in its own color and highlight its endpoints. Wires follow number order, matching the bend guide and solder checklist.

W1 · D10D8
W2 · E27E24
W3 · L27L24
W4 · G7I7
W5 · G9I15
W6 · E15H11
W7 · E23J25
W8 · L25L19
W9 · M18I11
W10 · B6B12
W11 · D12F14
W12 · G15K12
W13 · C5H5
W14 · J11K19
W15 · J20L23
W16 · H3M6
W17 · D21D17
W18 · C22E25
W19 · F17F12
W20 · G11K8
W21 · L7L8
W22 · K6I5
W1 · D10D8W2 · E27E24W3 · L27L24W4 · G7I7W5 · G9I15W6 · E15H11W7 · E23J25W8 · L25L19W9 · M18I11W10 · B6B12W11 · D12F14W12 · G15K12W13 · C5H5W14 · J11K19W15 · J20L23W16 · H3M6W17 · D21D17W18 · C22E25W19 · F17F12W20 · G11K8W21 · L7L8W22 · K6I5

5. Solder connections

Bottom view: horizontally mirrored. Coordinate names still identify the same physical holes. Highlights mark wire endpoints; wire routes belong on the component side. Check each connection and the listed solder bridges.

Board is horizontally mirrored. Column A is on the right.

W1 · D10D8
W2 · E27E24
W3 · L27L24
W4 · G7I7
W5 · G9I15
W6 · E15H11
W7 · E23J25
W8 · L25L19
W9 · M18I11
W10 · B6B12
W11 · D12F14
W12 · G15K12
W13 · C5H5
W14 · J11K19
W15 · J20L23
W16 · H3M6
W17 · D21D17
W18 · C22E25
W19 · F17F12
W20 · G11K8
W21 · L7L8
W22 · K6I5
W1 · D10D8W2 · E27E24W3 · L27L24W4 · G7I7W5 · G9I15W6 · E15H11W7 · E23J25W8 · L25L19W9 · M18I11W10 · B6B12W11 · D12F14W12 · G15K12W13 · C5H5W14 · J11K19W15 · J20L23W16 · H3M6W17 · D21D17W18 · C22E25W19 · F17F12W20 · G11K8W21 · L7L8W22 · K6I5