Create a simple megaphone

In this chapter you will use an amplifier chip to build a simple megaphone. storytelling by Stefanie Wuschitz


(most of this is available at Conrad, Radio Shack or other electronic stores in your neighborhood) 1 board 10-15 wires Solder A Soldering iron Helping hands An amplifier chip named LM386 220 uF capacitor 100 uF capacitor Rechargeable 9 Volt battery (or lots of lemon batteries or solar cells) A battery clip A piezo microphone A speaker (you can take the speaker out of an old speaker set just by removing the case)

About the individual parts:

Board: This is just a piece of plastic covered in holes, but the holes are coated in conductive material. You can get one for less than 2 EUR.

You will need to buy this.


It’s best to get wires in two different colors and cut them into 5 cm pieces.

Soldering iron:

They make it easier to keep all elements stable while you solder them together, plus you don‘t burn your fingers!

Helping hands:

They make it easier to keep all elements stable while you solder them together, plus you don‘t burn your fingers!

Amplifier Chip: This is named LM386, and looks like an insect with a little notch on its head. The leg at the left side of the notch-head is leg number one. Count counter clock wise from leg number one and give each leg a different number.
220 uF capacitor and 100 uF capacitor: Capacitors are used to collect electrons and then smoothly release them all at once. They are almost like batteries, but unlike batteries they cannot hold electrons for a long period of time. Instead, they only hold them for a short moment.
Rechargeable 9 Volt battery: You will need to buy this. Alternatively, you can use a lot of lemon batteries in serial or your solar cells instead.
Battery clip: You will need to buy this – it connects the battery with two wires, making it easy to connect to the board.
A piezo microphone:

You will need to buy this too. It is basically a contact mike, like people use to amplify acoustic guitars. If you attach it to a surface, it can pick up very minimal sounds and vibrations.

An old speaker: Just open up the chasing of old speakers.

The chip in our circuit is called LM 386 and it can strengthen any incoming signal. In our case it receives sound input through a small microphone (called a piezo). The LM386 amplifies the sound signal and sends it to your speaker. To make this circuit durable you will solder all the necessary pieces to a board.


Soldering is the process of joining two metals together so that electrons can travel between them. This means that the connection between the two metals becomes conductive. An example of this is two pieces of wire within an electric circuit. We also require a third substance called a ‘solder’, which is a kind of glue to make them stick together.
Soldering is not a mechanical process like glueing, it is a chemical process. The two metals or wires you’d like to fuse together will need to touch and get really hot at the same time, and the ‘glue’ - the solder - must melt between them. Once the melted solder gets cold again it turns hard. The two metal pieces are then stuck together and can conduct electricity.

Take a soldering iron and melt some solder on it. The melting point is around 230ºC (or 460ºF). Take the melted drop of solder off the tip of your soldering iron by rubbing it against a moist sponge. The drops of solder on the sponge will turn into beautiful tiny round pearls. The peak of the soldering iron should now have a silvery surface from the solder.

You can start!

First melt some solder on the tip of the first piece of wire, then melt some solder on the tip of the second piece of wire. Then make them touch and at the same time heat them with the hot tip of your soldering iron. The solder melts, cools down and the two wires are connected. Congratulations.

Now you can try soldering a wire to a small circuit board. Pull the tip of the wire through a hole in the circuit board. Use the tip of your soldering iron to heat both the wire and the little shiny ring around the hole of the circuit board. Now melt some solder onto the wire inside the ring. The wire should now be connected to the board. Congratulations.
Note: If you are pregnant, you should not solder, because of the toxic fumes.

You are now ready to start the circuit:

Attach the LM386 to the board. Every leg of the chip-insect should go through a hole in the board. Bend their toes once they are pushed through the board, so that the chip stays there. Now solder all legs to the board. Next you should connect the following wires: The red wire of the battery clip (plus/power) with the chip’s leg number 5. You need to push the battery clip’s red wire through the hole at the right side of leg number 5. Then you should connect the following wires: Connect the chip’s leg number 3 and 4. Connect the black wire of your battery clip (minus/ground) into the hole next to the chip on the left side. Connect the minus wire of your piezo and the minus wire of your speaker to the row of holes on the board. Now connect the piezos red wire (plus / power) with the chip’s leg number 2.
The capacitor has a long leg and a short leg, like the LED. The short leg is for minus (ground) and the long leg is plus (power). Connect the 100 uF capacitor with the short leg to the chip’s leg number 1 and the capacitor’s long leg with the chip’s leg number 8. You're almost done! Connect the 220 uF capacitor’s long leg with the chip’s leg number 5. Connect the capacitor’s short leg to an empty hole on the board right next to where you connected the red wire (plus/power) of your speaker. Now plug the battery to the battery chip and talk into the piezo microphone!