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CNC template · Circuit boards
Continuity tester with buzzer
Beeps and lights up as soon as the probes find a connection: for testing cables, fuses and traces. A BC547 switches buzzer and LED, powered by a 9 V battery.
- Size
- 56 × 44 mm, 1.6 mm thick
- Material
- Circuit board (FR4)
- Difficulty
- Beginner
- Milling time
- approx. 13 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 |
|---|---|---|---|
| 2 | Resistor 0.25 W | 1 kΩ Colour bands: brown, black, red, gold | R1, R3 |
| 1 | Resistor 0.25 W | 100 kΩ Colour bands: brown, black, yellow, gold | R2 |
| 1 | LED 5 mm The long lead is the anode; the flat side (cathode) points to the mark in the layout. | red | LED1 |
| 1 | NPN transistor Insert with the flat side as in the layout; do not swap the leads. | BC547 | T1 |
| 1 | Buzzer, active (3–24 V) Polarised: plus is marked on the case and goes on the square pad. | BZ1 | |
| 2 | Screw terminal 2-pin, 5.08 mm pitch | X1, X2 | |
| 1 | 9 V battery clip | ||
| 2 | Test leads with crocodile clips |
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 buzzer BZ1 with plus on the square pad; peel off the protective sticker only after soldering.
- Connect the battery clip to X1 (red to +) and the two test leads to X2.
- 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.
- Connect the battery: with no connection between the probes everything stays silent.
- Hold the probes together: the buzzer beeps and LED1 lights up.
- The tester already beeps at a few kilohms. It finds connections and breaks, but does not measure small resistances.
- 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.
