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Show HN: Raspberry Pi website hit tracking neon sign (davidsingleton.org)
82 points by dps on Feb 6, 2013 | hide | past | web | favorite | 20 comments

Wire it up to your bedroom light and you've got an instant DDOS alert system. Or a disco before it gets to that point.

That neon light flashes pretty fast. If you don't have a super high traffic website you should try to leave it on for at least a second so you don't damage the cathode or blow out the transformer.

According to the Google Store that light is around $28 bucks, meaning you're probably not dealing with the highest quality components (read: fire hazard).

The schematic may be incorrect, as it seems unlikely that the relay would energise in an emitter follower configuration, where it'd have approximately 2.6 volts across its coil in the "on" state. Perhaps the relay should be between 5v and the collector of the transistor. Some relays are sensitive enough, though, so I'm not sure.

I agree. If you look at the close up photograph of the final board (http://blog.davidsingleton.org/static/proto.png) it looks like he's got the following:

Relay connected to 5v with the diode across the coil. The base of the transistor goes to pin 18 via a resistor. The transistor is on the other side of the relay between it and ground.

That makes more sense to me because the diode is now actually protecting the Raspberry Pi 5V line.

The schematic is wrong, the relay and diode should be moved to be 'on top' of the transistor. But the circuit on the perfboard looks correct.

The diode goes across the relay coil because when the relay coil is turned off, there will be an inductive spike generated. The diode protects the transistor.

Thanks for pointing this out, folks - I made a mistake in the original circuit diagram. It's now fixed.

Where did you get your light? I love the idea of a light made into a word. If you had a light with the name of the website on it, you could have multiple websites with lights flickering to show when people were visiting each one. That'd be cool.

You could use EL wires [0] for a light made into a word.

[0] https://www.sparkfun.com/search/results?term=el+wire&wha...

UPDATE: If anybody is interested, it turns out you can special order these things with custom words on them. Looks like a great idea for promotional items.


I came to ask the exact same question.

Edit: I have a couple Android Mini PC devices. I wonder if I could do the same or similar with those somehow.

all these fun pi projects and mine is just sitting on my shelf...

fun project though, anyone making it go crazy yet?

Um, yes, it's going clickety clickety click - thanks HN!

haha, guess you should be glad you didn't decide to use a bell or siren!

You should record it through the HN rush.

I got this 8-relay board, and it's working beautifully with the Pi:


Extremely cheap, too.

Tried this out with a few LEDs on a cobbler. Works fine for a couple of hours and then ceases to flash. No crashing, error reporting. Has this worked for more than a day for you?

This looks pretty neat! I like it very much. It integrates a bit of electronics with some good old infrastructure design. Gotta say, I love it!

Great work, man.

Make a product of it. Half of management would such a thing

Check this out: http://indiegogo.com/aircubus

Exactly made for that very same reason. To visualize traffic and other notifications.

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