10 Year LED Flasher + PC Board





Introduction: 10 Year LED Flasher + PC Board

This LED flasher circuit will run for 10 years on a single 1.5v AA alkaline cell.

I have also included a PC-board. You can download it in PDF format here: PCB download . You will also find a component placement guide. Such long cell life is achieved by limiting average current drain to an initial value of 50uA(0.05mA) .

Step 1: PC-board and Component Placement Guide

DOWNLOAD LINK to PC-board and component placement guide.

I made this prototype using the Heatless (cold) toner transfer method

Step 2: Circuit Diagram & Component List

IC1: CD4001 (cmos quad NOR gates)

Q1: 2N4401 (NPN transistor)

C1: 100nF (0.1uF) ceramic capacitor

C2: 1nF (0.001uF) ceramic capacitor

C3: 10uF x 12v tantalum capacitor

R1: 4M7 resistor

R2: 2M2 resistor

R3: 4k7 resistor

LED: ultra-high efficiency LED (available current is very low)

T: 1/2" toroidal ferrite core & 2 meters (6 ft) of 24AWG (0.5 mm) enameled wire

BAT: 1.5 alkaline AA cell. (battery holder optional)

Step 3: Circuit Operation Details

Step 4: Making the Transformer

You can salvage the ferrite core from an old PC motherboard or power supply. Polarity of windings is important; if LED doesn't light when shorting header pins invert one of the windings.

Step 5: Measuring the Current Drain

Current drain should be around 50uA (0.05mA) when cell is new. You can adjust the current adjusting value of R2.

Step 6: For More Details, Watch the Video. Thank You !



  • Epilog Challenge 9

    Epilog Challenge 9
  • First Time Author Contest 2018

    First Time Author Contest 2018
  • Sew Warm Contest 2018

    Sew Warm Contest 2018

We have a be nice policy.
Please be positive and constructive.


3 Questions

Commercial equivalent or definition of transformer, please? How can I get them economically?


Hi , I am in the U.S. where can I get the parts to build this ?

where can I get the parts to make this 10 year flasher?


hi, the yellow capacitor is ceramic??? in circuit, this capacitor is
electrolytic capacitor??? when i'm not use this capacitor then led
flasher like video???


yellow cap is a 10uF tantalum electrolytic.

Can you post PC Board of version 1:


I pretty cool to follow the process of you tweaking the circuit to get it just a bit better :)

Compared to the first version you've replaced D1 (origional version) with the LED. What's the reson behind this change? Also I thought it would be required to keep the voltage across C3 (this version) from going beyond the rated voltage of the CD4001. How does it work now?


hi there!

First of all it's a matter of economy: why use a schottky diode if you don't need it?. In this circuit the LED itself is doing the rectifying. Additionally, there is now no restriction to the color of the LED (forward voltage drop). The voltage on C3 is a "balance" between charge, discharge and flyback voltage. The actual voltage with a new cell is around 5V (well below rated maximum voltage of 4001).

greetings --|>|---