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12 V battery traffic light
Shows the charge of a 12 V battery with three LEDs: red from about 10.5 V, yellow from 11.5 V, green from 12.5 V. Only Zener diodes, resistors and LEDs; for car, camper or solar system.
- Size
- 54 × 44 mm, 1.6 mm thick
- Material
- Circuit board (FR4)
- Difficulty
- Beginner
- Milling time
- approx. 12 min
- Bits
- Engraving bit 30°, PCB drill Ø 0.8 mm, PCB drill Ø 1.3 mm, Corn cob router bit Ø 2 mm
- Customise
- Fixed template, freely editable once opened
Free with an account · carve with Chrome or Edge · no installation
Build instructions
Parts
| Qty | Part | Value | In layout |
|---|---|---|---|
| 3 | Resistor 0.25 W | 470 Ω Colour bands: yellow, violet, brown, gold | R1, R2, R3 |
| 1 | Zener diode 0.5 W The band on the case is the cathode and sits on the side of the line in the layout. | ZPD 8,2 V | D1 |
| 1 | Zener diode 0.5 W The band on the case is the cathode and sits on the side of the line in the layout. | ZPD 9,1 V | D2 |
| 1 | Zener diode 0.5 W The band on the case is the cathode and sits on the side of the line in the layout. | ZPD 10 V | D3 |
| 1 | LED 5 mm The long lead is the anode; the flat side (cathode) points to the mark in the layout. | red | LED1 |
| 1 | LED 5 mm The long lead is the anode; the flat side (cathode) points to the mark in the layout. | yellow | LED2 |
| 1 | LED 5 mm The long lead is the anode; the flat side (cathode) points to the mark in the layout. | green | LED3 |
| 1 | Screw terminal 2-pin, 5.08 mm pitch | X1 |
You also need: soldering iron (about 30 W, fine tip), 0.5 to 1 mm solder with flux, side cutters and a multimeter.
Assembly
- Mill the board: isolate the copper first, then drill, and finally mill out the holes and the outline. The order is shown in the Milling panel.
- Cut through the holding tabs, deburr the edges and rub the copper bright with a scouring pad. After that, do not touch the copper side with your fingers.
- Use a magnifier and a continuity tester to look for leftover copper between neighbouring traces; cut any bridges with a craft knife.
- Insert the parts from the side without copper and solder them on the copper side. Fit low parts first: resistors and diodes, then sockets and transistors, and finally capacitors, terminals and large parts.
- Before soldering, compare the polarity with the component layout: band of the diodes, flat side of the LEDs, minus stripe of the electrolytic capacitors, notch of the ICs.
- Solder each lead for about two seconds at around 330 °C: tip on pad and lead, feed solder until it flows all round. Then clip the leads just above the joint.
- Fit the Zener diodes D1 to D3 in reverse direction: the band (cathode) points to plus, as in the layout. The value is printed small on the glass: 8.2 V for red, 9.1 V for yellow, 10 V for green.
- Visual check: no solder bridges, no dull, balled-up joints. Remove flux residue with isopropyl alcohol and an old toothbrush.
Test and power up
- Before switching on for the first time, check with the meter that there is no short between plus and minus of the supply. Power up the first time on a bench supply with current limiting if possible.
- On a bench supply, slowly raise the voltage from 9 V: red, yellow and green come on one after the other. The thresholds vary by a few tenths of a volt with the Zener diodes.
- Connect to the battery with a fuse (e.g. 1 A) in the plus lead.
- Finally protect the copper side against oxidation with solder lacquer or plastic spray.
How to carve this template
- OpenOpen the template in the app and adjust size and text if you like.
- CheckLook at it in 3D, check run time and warnings.
- Set upThe carve wizard guides you through material, clamping, bit and zero point.
- CarvePress start; the app drives your Grbl router directly over USB.
