My reverse geocache with nixie tubes

[liuzengqiang]

Real great idea RickP. I could also add a GPS sensor and give orders like "Jump in your car and exceed the speed limit on highway I-xx westbound for at least 30 seconds, near the bridge where cops normally hide"  

Maybe a safer way is to add a few tilt sensors and give an order to flip the box so that it would open just like pressing a few keys on the keypad in the right sequence, maybe safer this way

By the way, I just registered on geocaching not long age and I'm waiting for snow to melt in a few months so I can go on a few advantures with my wife. I will definitely design a flip-2-open box once I get a hang of the geocaching.

[wyager]

Hey,
thanks for the advice on the power supply. I got mine built and I'm only seeing around 60% efficiency when boosting from 5v to 170v (5v 170mA in, 170v 3mA out). I'm going to rejigger the circuit so that using 9v won't fry the attiny and see what happens then. It also seems that I can't get more than 130 volts with a 28000 ohm load, but this may be due to me capping the duty cycle at 98% (the attiny automatically adjusts duty cycle so the output is 170v). I'll work on it later today.


Edit:
GAHHHHH. I feel like screaming. I've spent the past five hours wondering why the #^%$ my boost circuit was only putting out ~70V after I tried to get it to work with 9V in. I proceeded to completely disassemble my perfectly soldered and very small boost circuit in order to exhaustively test every single component-of course, the component that had failed was the VERY last one I tested, and I only even tested it as an after thought. It was the output filter capacitor. There was no reason that thing should have failed, it was way over the required voltage rating. So now I have to re-assemble everything, and I'm out a really big filter cap. I almost trashed my inductor.

To anyone considering building a nixie clock, I HIGHLY recommend not building your own power supply, LOL.

On the plus side, it now works perfectly and holds stable at 9mA draw (set to regulate at 170v).

[pannen]

Now it's all over the net:

Make magazine: http://blog.makezine.com/archive/2011/01/nixie_tube_reverse_geocache_box.html

Gizmodo: http://gizmodo.com/5728632/this-clever-diy-briefcase-only-opens-when-youre-at-the-right-gps-coordinates

and various other sites. It's kind of cool, but I really hope the guy who this box is for (his birthday is in 4 days) doesn't stumble over it  :-/

[wyager]

I saw those! Congratz on the fame, it was a very cool idea. And plus, if he does stumble over it, he probably won't connect the dots until his birthday, at which point he will be all the more enthralled.

[William_WD]

Very awesome job there Great concept. Congratulations

[TheRedGingerBaron]

This is probably one of the cooler projects I have seen.

You should release instructions or blueprints somewhere so some of us can replicate it!

[williamanos]

Hi Rick. Could you please snap a picture of the correct wiring for the relay? I have a complete reverse geocache with everything fine and dandy except the switch mechanism. I've been fiddling around on the breadboard for hours and can't seem to make the arduino power itself down. The schematic you posted is helpful but I still find myself confused in the actual implementation. Thank you very much for all the info on your awesome project!

Will

[pannen]

Hi Rick. Could you please snap a picture of the correct wiring for the relay?

Will

I made a schematic for you - I hope that's helpful. Maybe you'll have to wire the pin 4 of the relay instead of pin 2 to the arduino 5V - I did this from memory

When you press the button the relay should latch and switch on the 5V for the arduino. If you put D2 to high it should switch the power off.

[edit]
Forgot the image


[/edit]

[mikalhart]

Rick, do you have any idea how much current that relay draws when it's in its quiescent (off) state?  Could your box last for, say, 6 months as long as the buttons weren't pushed?

Also, you mentioned the ability to use the button as both a power switch and an input to the Arduino, but I gather the circuit you share above doesn't show the latter?  If you wanted to add this, I guess you'd just connect the relay pin 1 line (from the button) to an Arduino digital input?

Thanks!  This is good stuff.

Mikal

[pannen]

Rick, do you have any idea how much current that relay draws when it's in its quiescent (off) state?  Could your box last for, say, 6 months as long as the buttons weren't pushed?

Also, you mentioned the ability to use the button as both a power switch and an input to the Arduino, but I gather the circuit you share above doesn't show the latter?  If you wanted to add this, I guess you'd just connect the relay pin 1 line (from the button) to an Arduino digital input?

Thanks!  This is good stuff.

Mikal

It doesn't draw any current. The latch relay is like a switch that is operated by magnetic coils. When it's off there's no connection between pin 2 and 3, so no current flows.

You can connect pin 1 to the arduino to use the pushbutton but if you do so you should add a clamping diode between pin 1 and 5 like on the other side. You need that because there is a short spike of energy with reversed polarity in a relay when you cut the power to a coil. That could damage your Atmega chip without the diode.

If you try this o a breadboard start by applying 5V to the relays coils (Pin1&5 and Pin6&10 in my schematic). You should hear the relay clicking if you put power to the alternate coils. Then check the resistance from pin 3 to pin 2 and 4 and you'll see how it works.

[edit]
BTW: Thanks for the tinyGPS library! I used it in this box
[/edit]

[mikalhart]

BTW: Thanks for the tinyGPS library! I used it in this box

Thanks!  Glad it was helpful.

One last question.  (I'd really like to try that relay solution.)  What species diode is that that you use to clamp against polarity reversals in the TQ2SA.

Mikal

[pannen]

One last question.  (I'd really like to try that relay solution.)  What species diode is that that you use to clamp against polarity reversals in the TQ2SA.

Mikal

A 1N4148 is recommended but if you just have a 1N400x you can use that, too.