903

4

4

This instructable will show you how to make a green frog with flashing LEDs. The LEDs that will be used are special LEDs. They turn on and off every second without any additional timer circuits.

The complete circuit will be placed inside the frog made from plasticine.

This is how the frog will look like in video: http://www.dailymotion.com/video/xxkdl2_blinking-frog_tech#.USCMsB2buro

You will need:
- flashing LEDs
- 9 V battery
- 9 V battery harness
- 470 ohm resistor
- electrical tape
- play dough

### Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

## Step 1: Assemble the Circuit

Assemble the circuit as shown in the picture.

Connect the anode the positive terminal and cathode to negative terminal. http://en.wikipedia.org/wiki/Light-emitting_diode

Longer leg is always the anode. http://www.sparkfun.com/tutorials/222

The LEDs conduct only in one direction. Thus you will have to flip connections if they are not conducting.

Do not forget to connect the 470 ohm resistor! You will burn the LEDs.

## Step 2: Electrical Insulation

Use electrical tape to insulate the wires. The reason for this step is that a short circuit might occur when the LED circuit is inside the frog because you cannot see what is happening there.

In the event of a short circuit the battery will become hot and might even explode!

## Step 3: Create the Frog

Create the frog from play dough.

## Step 4: Place the Circuit Inside the Frog

Place the circuit inside the frog.

Now you are finished.

Again look a the video: http://www.dailymotion.com/video/xxkdl2_blinking-frog_tech#.USCMsB2buro

This is how it should look like.

You can also try parallel connection for LEDs and note the difference in performance. For parallel connection use two 680 ohm resistors for each LED. Alternatively you cannot connect two LEDs in parallel to one 330 ohm resistor.

152 10K
88 8.2K
199 13K

## 4 Discussions

I used a special clay that becomes hard if left at room temperature for a few hours.