Introduction: Night-Owl Alarm

About: My name is Randy and I am a Community Manager in these here parts. In a previous life I had founded and run the Instructables Design Studio (RIP) @ Autodesk's Pier 9 Technology Center. I'm also the author of t…

This is a device that is designed to alert owls that it is nighttime. I made it for my little brother.


Step 1: Go and Get Stuff.


1 - Fake Stuffed Owl
1 - PC Board Grid-Style (Radioshack 276-150)
1 - PC Board IC-Style (Radioshack 276-159)
1 - 14 Pin Socket (Radioshack 276-1999)
1 - 9V Connector
1 - LM339 Chip (Radioshack 276-1712)
1 - SPST Rocker Switch (Radioshack 275-694)
2 - 2 digit 8 segment displays
1 - wire (black and red)
1 - 1K resistor
1 - photocell
1 - 9V battery
1 - 9V battery Holder (Radioshack 270-326B)
1 - tube of epoxy (not shown)


- soldering iron
- hot glue gun
- box cutter
- pliers


Most everything can be purchased at Radioshack. I got the 8-segment displays at The Electronic Goldmine ( Their part number was G4031. The owl should be purchased in San Francisco's Chinatown.

Step 2: Install the Power Switch.

Once you have your fake owl, the first thing you're going to want to do is install an on/off rocker switch. My fake owl came with a fake log. I decided to install my switch in that.

The first thing I did was cut a hole with my cutter that was approximately the size of the switch I was using. As well, I cut a small hole into the base of the log.

Then I soldered two long black wires to the terminals on the switch.

After that, it was a simple matter of unscrewing the black plastic clamp from the back of the switch, fishing the two black wires through the base of the fake owl and pushing the switch into place.

Finally, the clamp should be run along the two wires until it hits the back of the switch.

Screw it back into place.

Step 3: Spell Out the Word "SAFE"

Okay, now what you're going to need to do is to write out the word "SAFE" across both of your 2-digit 8-segment displays. You should do this on your breadboard first to make sure that it is right. V+ should go to two pins in the top middle on each of the segment displays. By connecting ground to any other of the pins you should light up a segment on that display. See the wiring diagrams below.

Once you are sure that the wiring is right, you could remove the segment displays (leaving all the wiring in place for reference). Now start soldering the displays into the Grid-Style PC Board so that the top of the display allows for the connection of one wire in each of the registers. Don't worry about the bottom half. The bottom half is a bunch of connections that essentially are connected to ground. The approach for this is to bridge all ground connections with solder and then bridge these connections to the middle register. The V+ connections are grouped in two sets of two on the top and should be bridged together to make two sets. These sets should be connected to each other via a wire on the top and then connected by another wire to a register on the side of the board.

Now connect a long red (V+) and a black wire (ground) to the display. These are the wires you are going to use ultimately to power the display and should be long enough to pass through the owl.

Step 4: Mutilate the Owl.

First off, you are going to want to cut a bigger hole in the base of the owl. I probably should have told you to do that to begin with.

Secondly, you are going to want to cut a square hole precisely the size of the displays into the front breast of the owl. This is where the displays are going to be placed, so they better fit.

Last, you're going to want to bore a tiny hole in the top of the owl's head behind its right ear. Pass a long red and black wire through this hole and ultimately through the base of the owl. Bend the wire so it can never fall through its head.

Step 5: Install the LED Display.

First, with a pair of needle-nose pliers you're going to want to carefully break apart the board the display is sitting on bit by bit until it is just large enough to be functional.

Now, using fishing wire or a long piece of stripped wire you're going to make guides to pull the display into place. Tie a loop on one side through two holes as close to the segment display as possible (see picture). Then do it again on the other side.

Pass the display inside the owl. Make sure both power cables from the display reach out of the base of the owl (NOT THE GUIDE CABLES!).

Use the wires you just attached to pull the display into place.

Once it is positioned correctly, glue the top right and bottom left corner into the owl with a hot glue gun. Hold it in place until it dries.

Finally, prepare some epoxy and use this epoxy to coat around the border of the displays. Let it sit for at least an hour.

Trim the guide wires once dry.

Step 6: Build the Circuit.

Essentially it is an LM339 chip and a voltage divider going to the positive input pin.

Solder your 14 pin socket to the board.

Pin 3 and Pin 14 are connected to power (red) and ground (black) respectively.

The 1K resistor goes from Pin 6 to Pin 3. I used a value of 1K, but you may need another value. Remember, not all photocells are created equal and the value of your photocell will affect the value of your other resistor.

Speaking of photocells, the photocell should go from Pin 6 to ground. But first you need to solder the photocell to the wires coming out of the top of the owl's head. Make sure the wires are not crossing and then insulate them very lightly with hot glue. And once the glue is somewhat dry then you should put a drop on the bottom of the photocell and glue it flush to the top of the owl's head. And finally you can connect the photocell to the circuit board. Make sure you are connecting the photocell wires and not the wires being dropped down from the LED display.

Now, take the connectors coming from the display and connect Pin 1 to ground and Pin 3 to power. That's it for that.

Attach the 9V battery connector to the board. Make sure you connect it in a way that you can attach a switch between ground on the battery and ground on the board. Attach the switch between ground on the battery and ground on the board

Note: do not go by the picture of my wiring. I accidentally switched the colors of the wires running off of the display board.

Step 7: Plug It In.

Put the LM339 chip into the socket.

Plug in the battery and see if it works.

It should work.

If it doesn't do anything at first, check the power switch. It might be off. If it still doesn't do anything, then it is time to troubleshoot by double-checking your connections.

Step 8: Glue Stuff Into Place.

First glue the circuit board into place inside the owl with the hot glue gun.

Now glue the wires from the 9V battery plug to the side of the case. You should glue the wire as close to the board as possible. The point of this is to keep the wire from being ripped out of place on the board by putting all the strain on the spot at where it is glued to the casing.

Lastly, using epoxy, coat the bottom of the 9V battery clip very well and attach it to the inside of the case. Let it sit for a few hours.

Step 9: Mail It to My Little Brother.

This device was designed for my little brother. He is not an owl and I am not sure he even likes owls. Regardless, you should mail your owl to him.

Since he is a minor and I would hate to give out his address to the entirety of the internet, I will instead give you the address of where you can ship it so that it can be forwarded to him:

*Address Coming Shortly*