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The TK20 at an angle: a black board with a wide gold border, a small clear light sensor near the top with C and E printed beside it, a capacitor and a resistor below it, a gold sun at the top right, lonely binary along the left edge, ANALOG in a box on the right, and a right-angle four-pin header labelled GND, VCC, NC and SIGNAL.3D
You have thistk20

Ambient Light Sensor

A phototransistor and a 4.7 kΩ resistor on a TinkerBlock board: light makes a current, the resistor turns it into a voltage, and SIGNAL rises with the light. A lit room reads low on the scale, bright light flattens just under VCC, and it sees near infrared best.

At 100 lux
0.24V, brighter reads higher
Tops out near
1230lux from 3.3 V
Most sensitive at
850nm, near infrared
VCC
3.3or 5 V, to match your board
Start here · 01 The four pinsOpen the board in 3D

Turn it over and see the three holes to wire: GND, VCC and SIGNAL. The light sensor is the small clear part at the top; SIGNAL rises with the light and tops out just under VCC, so match VCC to your board.

Product questions & answers ↓

The whole handbook10 articles · 50 minQuick referencePDF · 481 KBAmbient Light Sensor model (GLB)GLB · 805 KBAmbient Light Sensor CAD (STEP)ZIP · 700 KBAmbient Light Sensor drawing (PDF)PDF · 2.2 MBAmbient Light Sensor drawing (DXF)ZIP · 27 KBXYC-PT21C-L1 datasheetPDF · wmsc.lcsc.comPinout and specsThe pin table, and the questions people ask first
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Ambient Light Sensor

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Need another

Not on general sale yet. Reply to your order and we will sort out a spare — quote tk20.

Order or missing parts?

Email us or reply to your order, and quote tk20 — that identifies the product. If something is missing from the bag, your order is the record of what shipped.

Take it with you

Point a phone camera at the code and this page opens there. It is the same address as the one printed on your box, so it is also what to show someone you are passing the board to.