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CNC template · Circuit boards
Adjustable power supply with LM317
Delivers 1.25 V up to about 3 V below the input voltage, adjustable with a trimmer, up to 1.5 A with a heat sink. With protection diode, input and output capacitors and power LED.
- Size
- 66 × 42 mm, 1.6 mm thick
- Material
- Circuit board (FR4)
- Difficulty
- Intermediate
- Milling time
- approx. 16 min
- Bits
- Engraving bit 30°, PCB drill Ø 0.8 mm, PCB drill Ø 1 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 |
|---|---|---|---|
| 1 | Resistor 0.25 W | 240 Ω Colour bands: red, yellow, brown, gold | R1 |
| 1 | Resistor 0.25 W | 4,7 kΩ Colour bands: yellow, violet, red, gold | R2 |
| 1 | Trimmer, vertical | 5 kΩ | P1 |
| 1 | Ceramic capacitor | 100 nF | C1 |
| 1 | Electrolytic capacitor Polarised: the stripe on the case is minus, the long lead is plus (square pad). | 10 µF / 35 V | C2 |
| 1 | Rectifier diode The band on the case is the cathode and sits on the side of the line in the layout. | 1N4007 | D1 |
| 1 | LED 5 mm The long lead is the anode; the flat side (cathode) points to the mark in the layout. | green | LED1 |
| 1 | Adjustable voltage regulator Metal tab towards the mark in the layout; screw it down first, then solder. | LM317 | IC1 |
| 2 | Screw terminal 2-pin, 5.08 mm pitch | X1, X2 | |
| 1 | TO-220 heat sink with M3 screw and thermal paste |
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.
- Screw the LM317 to the heat sink (with thermal paste) and only then solder it; the metal tab is connected to the output and must not touch the case.
- For high currents, reinforce the input and output traces with solder.
- 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.
- First turn trimmer P1 so that the output has the lowest voltage.
- Apply 5 to 35 V DC to X1, plus to VIN.
- Measure at X2 and slowly turn P1 up. The output voltage is 1.25 V × (1 + P1 / 240 Ω); LED1 lights from about 3 V.
- 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.
