There are some projects that just take your breath away, this 555 Decimal Adding Machine by Alan Yates is definitely one of those.
Via: EMSL
“The quiescent device pulls 450 mA from its 9 volt supply. Yep, 4 watts! You can feel the warmth coming from the back of it. I could not find ICM7555s in quantity, so was forced to use LM555CNs, making it a rather power hungry device. The LEDs pull only about 70 mA total, the rest is just burnt up in the 555s.”
