Introduction: Cheap Touch Lamp
In this Instructable you will be building a touch lamp constructed from a minimum amount of components for proper operation.
There are two videos and the second video shows how adding an additional Re2 resistor improves the circuit performance. If you look at the video in this step then you will see that the bright LEDs are not turning off because the Re2 resistor is not yet connected. The video in the next step shows the circuit working with the Re2 resistor.
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DIY Electronics: https://www.instructables.com/id/Touch-Lamp-1/
Recycled Circuits: https://www.instructables.com/id/Recycled-Componen...
small matrix board, bright LEDs - 2 (you only need on but you might burn a few), General purpose NPN BJT Transistors - 5, scissors, 1 kohm resistor, 100-ohm resistor - (one for each LED), wires, power source, pliers. (battery/power supply).
Optional: wire stripper, 10 kohm resistor.
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Step 1: Build the Circuit
You can see that I did not use a soldering iron.
Calculating Rd value is very simple.
Rd = (Vs - Vd) / ILED
ILEDis 10 mA per LED connected in parallel.
Vd is 2 V per LED connect in series.
For 6 V battery, 2 LEDs connected in parallel the Rd value will equal to:
Rd = (6 V - 2 V) / 20 mA = 400 ohms or 470 ohmswhich is available in practise.
For 9 V battery, 2 LEDs in series the Rd value will equal to:
Rd = (9 V - 4 V) / 10 mA = 5 V / 10 mA = 500 ohms or 560 ohms which is available in practise.
Check out the E12 resistor series: