• Featured User: kurt


    Open-source hardware project hosting is my passion. I spend most of my free time building neat gadgets or planning what I'll build next. I love building things, and I want to make Open Hardware Hub a place that inspires others to build, ...

    Learn More

  • Updates 2013 February 18

    It's been a while, hasn't it? Well, that's ok because we've got a lot of updates to talk about. Most of these have been effective on the site fora couple weeks now. A few may or may not be active when this article gets posted, but they'll certainly be applied in the ...

    Find Out More

Scavenger Hunt Beacon

Download this project


By: kurt

Use this beacon to broadcast secret messages with infrared light. Only people with the Scavenger Hunt Beacon Decoder can read your messages. Place a couple of these around your town and have each one broadcast a clue about the location of the next one.

Download project description w/o images
Download project description w/ images


Download all project files

Bill of Materials

Qty Part # Description Schematic ID Source
1 6617fc64225774b905ddbcb68b5dc2785d2aea63 ATTINY13-20PU IC, 8BIT 1K FLASH MCU, DIP8 IC1 Source
1 23152b528919879cc83ae0182f8e0d0df8cffa53 CR2032 Lithium Battery Bat1 Source
1 84eda0cdd871229ce7ce81453bf8afb82dd8fcd1 QED234 IR Emitting Diode LED1 Source
2 8d17dc6357d99d17730430c3718a0a959d650925 CF14JT100R 1/4w 100 ohms 5% Carbon Film Resistors R1, R2 Source
1 F77d761c5f8c8327105b390be92e4fd7832e6247 1-390261-2 SOCKET IC, DIL, 0.3", 8WAY IC1 Source
1 01f3c08eb655b890c74db18c16f97e2a801bbf3a BS-7 HOLDER COINCELL 2032 RETAINRCLIP Battery Holder Source
1 B10fcd91e54061e9748ca26c34782bc79400bf95 WP7113LID 5MM LOW CURRENT RED LED, LAMP THOLE, BULK LED2 Source
loading total from bomfire.com...

Download BOM w/o images
Download BOM w/ images


1. Collect Parts

Make sure you have everything in the parts list.

You can get the PCB by going to BatchPCB and submitting the GERBER files above for processing.


2. Solder Resistor

Solder the first 100 ohm resistor into place.


3. Solder IC Socket and Resistor

Solder the second resistor into place. Solder one of the socket legs in place. Then use one hand to push the socket all the way into the board while using your other hand to re-melt the solder on the socket leg. This way you can make sure the socket is well-seated. Continue by soldering the rest of the socket legs.


4. Solder LEDs

The LEDs can be solder into either position. It doesn't matter because both LEDs are lit simultaneously. Match up the flattened sides of the LEDs with the artwork on the board. (Ignore the + marks by the LEDs. They are wrong.) Solder the leg closest to the edge of the board of each LED. Then adjust the position of the LED by pushing it flush with the circuit board while re-melting the solder. Once the LEDs are positioned properly, solder the remaining LED legs.

Img_0473 Img_0474 Img_0475

5. Solder Battery Clip

Solder the battery clip to the back of the board. You may have to push hard to get the battery clip into the holes for it. You do not have to fully insert the battery clip. Just make sure that your solder makes a secure contact between the leads of the battery clip and the holes.

Img_0476 Img_0477

6. Insert Battery

You can now insert the battery. The battery will not drain while inserted if the IC is not in the IC socket.

Img_0478 Img_0479

7. Customize Messages

Open the AVR Studio Project from the files section in AVR Studio. Replace the stuff in the quotation marks on lines 24-27 four messages of your choice. (You can easily modify the code to display more or fewer messages, but I'll leave that as an exercise for the reader!) Compile the project into a .hex file by clicking Build-->Build Solution in AVR Studio.

Custom_messages Build

8. Program ATTiny13

Use an AVR programmer like the "Scavenger Hunt Beacon Decoder" to program the ATTiny13 with the .hex file you created in the last step.


9. Insert ATTiny13 in IC Socket

Put your programmed ATTiny13 in the IC socket. The LEDs will now blink your message every 8 seconds. When the ATTiny13 is not blinking your messages, it enters a low-power sleep state to conserve energy.


Download steps w/o images
Download steps w/ images


2 -
1 - Initial project release
Add revision

blog comments powered by Disqus