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) .

DOWNLOAD LINK to PC-board and component placement guide.

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

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)

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.

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