Blue led dies rapidly on 9v battery but ok on cr2032 lithium coin cell
Don't try this at home - a blue LED connected directly to a 9v battery without a current limiting resistor…
Cheap led voltmeter measures up to 30v has 2 decimal places accuracy
For about £3 (including postage) you can buy this LED voltmeter which had 2 decimal places of accuracy. It measures…
Using constant current psu to drive leds in gu10 spot light
Took apart this faulty GU10 LED spot light to see if the LEDs can be made to light. Using a…
Battery powered christmas tree lights – blue leds fade first
The blue LEDs on my cheap battery powered Christmas tree light go out long before the other colours. Why? I'm…
Soldering surface mount devices to a single sided pcb
My PWM5 Solar Charge Controller (www.256.co.uk) uses 3 surface mount devices (a capacitor and 2 resistors) on the PCB. Attaching…
1.4ah power tool battery v 1.9ah aa cell – do the maths!
The little AA cell has a higher Amp-hour rating than the big lithium power tool battery - what's that all…
1aa led torch roundup – lenser fenix flashlight
A quick roundup of single AA LED torches. Featuring Fenix and LED Lenser models. All these flashlights have the necessary…