The Crap Badge is driven by the venerable 555 with 20 LEDs round the perimeter of the badge triggered by the lovely CMOS 4017. Capable of driving only 10 LEDs, the 4017 is augmented with a little help from the second CMOS family member, the 4027. JK flip-flopping its way from the carry-out of the 4017 it drives transistors to change the series of LEDs that are being driven.

All this is powered by the humble CR2032 (You could use the smaller CR2016) and attached through a shirt or t-shirt using a magnet (not included, sorry, turns out it isn't very helpful for the postal service). Depending upon the thickness of your clothing this method of attachment may be as crap as the name on the badge.

CRAP

1 - Something of extremely poor quality

1.1 - Nonsense

1.2 - Unwanted articles; rubbish

So far so run-of-the-mill... I wanted this badge to interactive or at least reactive to its environment. The 555 is arranged in Astable mode, a fancy way of saying you can adjust the frequency (speed) of its pulses. That means it will ping through the LEDs at a set rate with set resistors but throw a variable resistor in there and you can change it on the fly. Enter the Light Dependant Resistor (LDR)! Hooked up to the 555 it changes the speed of the LEDs cycling based on ambient light, the lighter it is the faster it goes.

All this is achieved with a current draw of around 2mA, you should get around 3 full days out of a fresh CR2032.

I made it because it is fun to play with CMOS circuits and an interesting nerd tag to mesmerise the masses.

Component list

20 x Yellow 0805 LEDs

1 x 100nf 0805 Capacitor

3 x 10k Ohm 0603 Resistor

2 x 2n3904 Transistor

1 x 3.2k Ohm 0603 Resistor

1 x 3v Battery Holder

1 x 4.7uf 0805 Capacitor

1 x 4017D CMOS IC

1 x 4027D CMOS IC

2 x 470 Ohm 0603 Resistor

1 x TLC555 IC

1 x Light Dependent Resistor

Battery not included

Assembly Instructions

Required equipment

• Something to solder small components
• Some solder
• A multimeter, you are going to need to measure the capacitors since they don't have values printed on them
• Tweezers, seriously some of the parts are tiny
• Patience

There are no component identifiers on the board, not to make it more difficult but to keep the crap aesthetic. So you will need a keen eye for diagrams. I chose not to include a pin in the kit to attach it to your clothes, they are hard to solder. Instead you will need a magnet, this will stick to the battery (not included) through a t-shirt or top.