In this project, I am going to show how to make a glowing keychain which consists of two LED's which starts glowing when two plates are made to connect on the keychain using fingers or any conducting materials.
How did I get this idea?
When I was making a project on water level indicator I noticed that when the Positive wire from supply and a wire from the base of the transistor were made to touch through water the led connected from the collector of transistor started glowing then I connected those two wires with my fingers it started glowing then I thought I can make a keychain using this technic and I made it.
Step 1: Working
The transistor is a three layer, three terminal, and two junction semiconductor device. Almost in many of the applications, these transistors are used for two basic functions such as switching and amplification. The transistor has three regions namely base, emitter, and collector.
(When the two plates are not connected. )
When collector-base junction and emitter-base junction are reverse biased. This in turn not allows the current to flow from collector to emitter when the base-emitter voltage is low. In this mode, the device is completely switched off as the result of the current flowing through the device is OFF, As shown in fig(a).
(When the two plates are connected. )
the emitter base and collector base junctions are forward biased. Current flows freely from collector to emitter when the base-emitter voltage is high. In this mode, the device is fully switched ON, As shown in fig(b)
Step 2: Materials
1. SMD Led's white, size(1206) 2nolink
(here I have used slightly bigger LED of )
2. SMD Resistor 51 ohm's size(1206) 3nolink
3. Transistor BC547 1nolink
4. Copper clad 1nolink
5. 3v Battery 1no link
6. 3v Battery holder 1no link
7. Photo sheet 1nolink
1. Soldering Iron set
2. Ferric chloride
3. Hand drill
4. Iron box
5. Nose player
Step 3: Making
1. Take the printout of the circuit on a photo sheet.
[ The pdf file is uploaded one of the file is having a small SMD led sized(1206) in the circuit and another file is having the SMD led sized(2512).]
2. Cut the paper and copper clad to the same size.
3. Place the printed paper on copper clad(printed side should be placed on the copper side of the board)
4. Place the iron box on the paper placed on the copper glad. Press the iron box on copper clad for 10-15min.
5. Remove the sheet from the board. (Trace the unprinted line using permanent marker)
6. Add the board into ferric chloride acid (mix the ferric chloride and water in the ratio of 1:2)
7. Keep the board in acid until the unwanted copper is removed.
8. Bend the transistor terminals such a way that (Emitter and collector) are turned towards the uneven surface of the transistor as shown in the image above.
9. Solder the components on the board.
10. Now insert the battery and it is ready to go.
11. Place your finger or any conducting material and it will start glowing.
Similarly, You can design yours and present it to Your loved one.
(I made this for my sir. so I printed his name on that and sorry for that I have uploaded that its self.)