The most-built circuit in electronics
A 7805 regulator board: 7 to 12 volts in from a barrel jack, a steady 5 volts out, and an LED that shows it's on.
Free build sheet
The parts, every wire with its length and bend points, a bend guide, both sides of the board and checkboxes to track your progress. Print it or keep it open at the bench.
Open the build sheetWhat you need
10 parts on a perfboard 14 × 25 holes, plus hookup wire.
| Qty | Part | Where to buy |
|---|---|---|
| 1 | Electrolytic Cap100uF C1 | Buy Electrolytic Cap on Amazon |
| 1 | Ceramic Cap0.33uF C2 | Buy Ceramic Cap on Amazon |
| 1 | Ceramic Cap0.1uF C3 | Buy Ceramic Cap on Amazon |
| 1 | Electrolytic Cap10uF C4 | Buy Electrolytic Cap on Amazon |
| 1 | Diode (axial) D1 | |
| 1 | Barrel Jack J1 | |
| 1 | Screw Terminal 2P (5.08mm) J2 | |
| 1 | LED LED1 | Buy LED on Amazon |
| 1 | TO-220 Q1 | |
| 1 | Resistor (axial)1k R1 | Buy Resistor (axial) on Amazon |
Check every pin against the datasheet of the exact part in your hands before wiring.
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Cut list
7 wires, 156 mm (6.1 in) in total, in the order the build sheet cuts them. Wire numbers match the build sheet. Each length includes 5 mm per end to go through the hole.
| Wire | Colour and net | Length | ||
|---|---|---|---|---|
| 6 | BlackGND J21 → F21 | J21 → F21 | 20mm | Straight |
| 5 | BlueGND I17 → I20 | I17 → I20 | 18mm | Straight |
| 4 | GreenGND G13 → F16 | G13 → F16 | 20mm | 8mm (90°) |
| 1 | RedLED_A F19 → I19 | F19 → I19 | 18mm | Straight |
| 7 | RedGND H12 → K5 | H12 → K5 | 35mm | 23mm (90°) |
| 3 | WhiteVOUT E14 → D21 | E14 → D21 | 30mm | 8mm (90°) |
| 2 | YellowVOUT D15 → D13 | D15 → D13 | 15mm | Straight |
About this build
This is the 7805 linear regulator, probably the most built circuit in electronics. A barrel jack takes seven to twelve volts in, and a screw terminal hands out a steady five volts.
A 1N4007 diode sits in series with the input, so a reversed jack can't push current backwards into the board. Each side of the regulator gets a bulk electrolytic and a small ceramic: 100uF and 0.33uF on the input, 10uF and 0.1uF on the output.
A 1k resistor and an LED hang off the output rail, so you can see at a glance that the five volts is alive.
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