Annoying Police Lights

Sunday morning, not in the mood for anything complex but I’d just purchased a pair of ATTINY85 chips and I was looking for a quick test project. To explain, the ATTINY85 is an 8-pin mini-processor, a kind of toy Arduino chip. Easily programmed from the free Arduino IDE with a handy Arduino (no need for a special programmer) the chips are ideal for simply flashing lights and possible more complex projects but due to lack of memory and interrupts don’t think you’re going to be able to make something really complex with these.  On the upside however they need NO external components to operate – i.e. no crystal, no reset, nothing.  They can quite happily operate at around 8Mhz from an internal oscillator.

Of course you’re going to want to see for yourself – hence the policy flashing light project. Now if someone were evil enough once could have a whale of a time catching speeding motorists out with this but I would not recommend it as it’s probably illegal and you’re likely to get punched… but it’s a nice thought. This little project from a distance will look all the world like it’s mounted on a policy car.

Rather than rant on here I’ve put the whole lot into a short video. You’ll need a PC with Arduino IDE1.0 or better, an Arduino of some sort and the bits to make the project up i.e. 2 or 4 LEDS, a battery and an ATTINY85 chip. All the details are in the video as is the code near the end.

You could go up to a maximum of 3 BLUE and 3 RED LEDS – OR of course if you REALLY want to go to town, just use 2 of the outputs, stick a couple of BC337 transistors on the outputs (via 470r base resistors) and feed 2 LED STRIPS – one RED, ONE BLUE…from 12v.   Hey… you could make a REAL police car (well, not quite)..


ATTINY85 driving LEDs in a format like Police Car strobes.

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