LBLonely Binary Learn
Shop
AMS1117/The boards in your box/03. The two boards
The boards in your box · 03 of 11

The two boards

Eighteen boards fixed at 3.3 V and six you set yourself, the same size and the same three pins. Flip one over to tell them apart. The one with the LED gives 3.3 V; the one with the trimmer gives whatever you set.

Updated 2026-09-114 min readAMS1117

One panel, two kinds

The twenty-four boards arrive joined in a single panel. One row of six is the adjustable board; the other eighteen are fixed at 3.3 V. Snap off what you need.

The panel of 24 boards from both sides: on the left, four rows of six with the chip and capacitors facing up and GND OUT VIN printed along each; on the right, the backs, where the top row of six shows white trimmers and the lonely binary logo and the other three rows are printed 3V3 in a gold box.
Both sides of the panel. The six adjustable boards are the top row on the right, trimmers showing.

Both boards are 9.0 × 16.5 mm, with the same chip in the same place and the same three holes along one end. Pick a board and a part:

Every part on the board, and what it is for
3V3 · The chip
Board
Show me
The chip. U1, an AMS1117-3.3. Its three legs are GND, OUT and VIN, left to right — the same order as the header. The wide tab at the top is OUT too, not ground.

The 3V3 board

An AMS1117-3.3, two capacitors on each side of it, and a red LED with its 1 kΩ resistor. The LED is on the output, so it shows that the regulator is working, not just that power is arriving.

The ADJ board

An AMS1117-ADJ and the same four capacitors on the front. On the back, a 2 kΩ trimmer and a 220 Ω resistor set the voltage, and a white panel waits for you to write down what you set it to.

The back of the adjustable board: the lonely binary logo in gold at the top, a blank white rectangle in the middle, a white square trimmer with a cross-shaped slot lower left, a small resistor to its right, and VIN, OUT, GND printed above the three holes.
The back of an ADJ board. The trimmer takes the screwdriver from the box; the white panel takes a pen.

There is no LED. One would stay dark at the lowest settings, below the 1.8 V or so a red LED needs to light, so the only way to know what an ADJ board is putting out is to measure it.

When it does not work

Which of my boards is which?

Turn it over. The 3V3 board says 3V3 in a gold box on the back. The ADJ board has a small white trimmer and a blank white panel there instead. From the front, only the 3V3 board has an LED.

The LED on the 3V3 board is very dim

It is meant to be. A 1 kΩ resistor limits it to 1.5 mA at most, enough to see in a room and small enough not to matter to a battery. It is lit whenever there is voltage on OUT.

Do I have to solder the pins on?

If the header pins are loose in your box, yes: cut a strip of three and solder it to each board you use. Three joints, and the board then sits in a breadboard like any other module.

Is the ADJ board a worse 3.3 V board?

Set to 3.3 V it works as one, but a trimmer can be knocked and the 3V3 board cannot, and the ADJ board has no LED to show it is on. Use the 3V3 boards for 3.3 V and keep the six ADJ boards for everything else.

Alongside this page
Soldering the three header pinsWhat the small capacitors either side of the chip are for
Where this goes next

Which is which from the front, why the back reads the other way, and what each mistake does.

Three pins: GND, OUT, VIN →

Edit this page — content/books/ams1117/the-two-boards.mdx

Community

Questions about this product

See what other owners have asked, and read their solutions.

Ask a question ↗

AMS1117 LDO Regulator Kit, 24 Boards (18 × 3.3 V, 6 × Adjustable)

Loading discussions…

View all on the community ↗Read here. Sign in to the community to post or reply.

Discuss this article

Ask about this page. The answer stays here, on the page it belongs to, for whoever hits the same wall next.

Browse Modules and blocks on the forum →

← 02How a regulator holds still04 →Three pins: GND, OUT, VIN