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Forum 2005-2010 (read only) => General => Exhibition => Topic started by: pannen on Dec 31, 2010, 01:24 am

Title: My reverse geocache with nixie tubes
Post by: pannen on Dec 31, 2010, 01:24 am
Hi,

over the last month I built a reverse geocache that is trackable on geocaching.com, uses nixietubes and looks cool :)

At first I used an lcd display that that seemed a bit boring for what I was planning.

So I bought some IN-12B Nixie tubes with driver ICs from ebay. They where pretty cheap (20$ for 6 tubes, connector pins and ICs) and they have a decimal point. With 3 of these I can display from 10 meters (0,01km) to 999km.

These tubes need 180 Volts so I also got a small DC-DC boost converter. Each tube needs one driver ID that has a 4bit binary input for switching on a number in the tube.

I also need another driver chip for the decimal point (with just two connected inputs) and a signal to switch the nixie powersupply on and off - That makes a total of 15 data pins. Because I wasn't sure that I had enough IO pins left on the arduino I added a 4bit binary counter to the nixie drivers, that reduced the needed IO pins to 9 - I could have reduced that more, but so I have 9 pins left, that's enough for this project.

The finished nixie board:
(http://i53.tinypic.com/4htcp5.jpg)

The back (Yes, next time I will make a real board :) )
(http://i51.tinypic.com/20p7ixj.jpg)

The rest ist pretty straightforward, I added a serial GPS module, 2 LEDs and a servo and mounted all of it on a board:

(http://i52.tinypic.com/zu605k.jpg)

The box for this is a metal box from the french army (medical box). A friend with a CNC lathe made the cuts in the lid.

This is the locking mechanism:
(http://i52.tinypic.com/ayua02.jpg)

And this is the painted box:
(http://i55.tinypic.com/2rm6001.jpg)
The red bars are ikea door handles :)

The GPS-LED blinks while it's trying to get a fix. If it gets one within 3 minutes, the GPS-LED lights solid and it displays the distance or opening 'animation' for 8 seconds and switches off. It it can't get a fix, the Error-LED lights for 8 seconds and it switches off.

The on-off switch is built with a latch relay, so it's really off when not operating.

The box contains 4 D Cells because the tube draw a lot of power.

When someone has opened the box he'll find instructions inside on how to reprogram it via usb and a serial console. I made a special serial dialog to enter new coordinates.
Title: Re: My reverse geocache with nixie tubes
Post by: retrolefty on Dec 31, 2010, 01:28 am
Wow dude, that is cool looking. Just never ever try and bring that thing through any U.S. airport. They will take you somewhere even GPS can't track.  ;D

Lefty
Title: Re: My reverse geocache with nixie tubes
Post by: pannen on Dec 31, 2010, 01:35 am
Quote
Wow dude, that is cool looking. Just never ever try and bring that thing through any U.S. airport. They will take you somewhere even GPS can't track.  ;D

Lefty


I thought about that. Wouldn't be wise to take it on a european flight either. It'll will be even funnier if they ask you to open it and you'll have to explain that you can't - at least not there :)
Title: Re: My reverse geocache with nixie tubes
Post by: retrolefty on Dec 31, 2010, 01:47 am
Quote
It'll will be even funnier if they ask you to open it and you'll have to explain that you can't - at least not there


OMG, that would be a very bad reply. Better get a good lawyer on retainer before traveling with that thing.

Lefty
Title: Re: My reverse geocache with nixie tubes
Post by: VA3SU on Dec 31, 2010, 01:59 am
Doesn't need to bring it to an airport. Anywhere in Boston would be good.

Kevin
Title: Re: My reverse geocache with nixie tubes
Post by: pannen on Dec 31, 2010, 02:20 am
Stupid terrorists are ruining all the fun.

BTW: Are you already a suspicious person in the US if you like to tinker with electronics in your spare time?
Title: Re: My reverse geocache with nixie tubes
Post by: Valalvax on Dec 31, 2010, 02:28 am
http://www.boston.com/news/globe/ideas/brainiac/2007/02/boston_bomb_squ.html


This is what the Boston reference was to, also the Aqua Teen thing the month before, just google Boston Bomb Squad
Title: Re: My reverse geocache with nixie tubes
Post by: retrolefty on Dec 31, 2010, 02:29 am
Quote
BTW: Are you already a suspicious person in the US if you like to tinker with electronics in your spare time?


No, of course not. Only if suspected of something illegal from other evidence would your personal interests, knowledge, and capabilities come into play during further investigation, trying to connect the dots so to speak. I wonder if shoe repair persons could flag interest these days.  ;)
Title: Re: My reverse geocache with nixie tubes
Post by: Valalvax on Dec 31, 2010, 06:22 am
You can get on "High risk" lists, I know I'm probably on one, I know that everytime I travel I am "randomly selected", even though I'm white, born and raised here... and as far back as I know my family is full blood American (as far back as I know is to my great great great I don't know how many greats grandfather Sam Houston (As in Texas)

Why I gave all that unneeded information, I don't know :/


Anyway, cool project
Title: Re: My reverse geocache with nixie tubes
Post by: mikalhart on Dec 31, 2010, 12:54 pm
Cool...!  How does that "latch relay" business work for the on/off switch?  I'd like to use that for some of my projects.

Mikal

PS I used to live in the hometown of Sam Houston (Huntsville).

Title: Re: My reverse geocache with nixie tubes
Post by: liuzengqiang on Dec 31, 2010, 06:24 pm
This thing is awesom! You must be an artist to most of us to pull off the look. I love the spaghetti monster perfboard! No one will figure out what is doing what with all same color wires. So who is this for?
Title: Re: My reverse geocache with nixie tubes
Post by: retrolefty on Dec 31, 2010, 06:49 pm
Quote
How does that "latch relay" business work for the on/off switch?


Here is a simple drawing of a manual-on, auto turn-off power switch I build using a single coil +5vdc relay I found available on e-bay. You press the switch to turn on power and the first instructions in the processor is to turn the output pin high to latch the power on. When the program wants to power off, it just takes the output pin low.

http://img25.imageshack.us/img25/563/08miq7.jpg

Lefty
Title: Re: My reverse geocache with nixie tubes
Post by: pannen on Dec 31, 2010, 07:21 pm
Quote
How does that "latch relay" business work for the on/off switch?


I used the Panasonic TQ2SA-L2-5V. You can switch it on and off with 5V.When you press the pushbutton the battery current switches it to on. The button press is also routed to an arduino pin, so I can use the pushbutton as an input (secret combination of timed presses to open the box). The relay's coil for switching it off is attached to an arduino output pin, so the arduino can switch it's own power off by putting that pin on high. It's pretty simple to build, I just added two diodes to the relay. I made some drawings on paper, but I think they aren't readable to anyone but me :)

If you want something like this you could also buy the plololu switch. That does the same with solid state components but doesn't allow the pushbutton to be routed to the arduino (http://www.pololu.com/catalog/product/750).

Quote
So who is this for?


A work buddy of mine who is really into geocaching is turning 30 in two weeks. He'll get the box with his present inside.

The plan is, that he'll pass it on to another friend once he opened and reprogrammed it.

Every owner can log his experiences with the box on geocaching.com by using a geocode that is spray painted on the box (If you ever did geocaching: It's treated like a travebug - The groundspreak rules aren't allowing moving caches).

The url for tracking the box is: http://www.coord.info/TB3W7NC
Title: Re: My reverse geocache with nixie tubes
Post by: bld on Dec 31, 2010, 09:37 pm
That paintjob is awesome!!!
Title: Re: My reverse geocache with nixie tubes
Post by: mikalhart on Dec 31, 2010, 10:14 pm
@Lefty,

My worry for a design like yours is that there is a significant lag between when power is applied and the first user instructions are executed.  Especially when you're using a bootloader, isn't this interval something like 2 seconds?  Doesn't that mean that the user has to push the button a long time before the processor can latch it?

@RickP,

So the basic principal of operation of your circuit is similar to that of the Pololu switch?  Cool.  Thanks for sharing.

Mikal
Title: Re: My reverse geocache with nixie tubes
Post by: retrolefty on Dec 31, 2010, 10:32 pm
Quote
Especially when you're using a bootloader, isn't this interval something like 2 seconds?  Doesn't that mean that the user has to push the button a long time before the processor can latch it?


Yes, it would be dependent on the specific bootloader used as to how long the bootloader decides to time out and jump to start the preloaded sketch. I've been using the modified Adafruit bootloader for quite awhile sense one benefit is that there is almost no delay at all for the sketch to start on initial power-up. That bootloader also handles WDT interrupts better. Not sure what the delay is on for the new Uno bootloader. Slow to start bootloaders with long startup delays are so 2009.  ;)

Lefty
Title: Re: My reverse geocache with nixie tubes
Post by: mikalhart on Dec 31, 2010, 11:30 pm
Thanks, Lefty.  Any idea how long that time delta is on the Uno?  If it's just a couple of hundred milliseconds, it's probably reasonable.  Thanks!

Mikal
Title: Re: My reverse geocache with nixie tubes
Post by: rmeister on Jan 03, 2011, 10:22 pm
great job! i am totally digging the design.

when you said that it was trackable on geocaching.com, i thought you were saying that it was when the gps received a signal it send an update to geocaching about where the trackable was located. Is this even possible?
Title: Re: My reverse geocache with nixie tubes
Post by: pannen on Jan 04, 2011, 12:01 am
Quote
great job! i am totally digging the design.

when you said that it was trackable on geocaching.com, i thought you were saying that it was when the gps received a signal it send an update to geocaching about where the trackable was located. Is this even possible?


Yes, that's possible and I thought about it. It would need a gprs module like this: http://www.cooking-hacks.com/index.php/shop/arduino/arduino-gprs-module.html

With that one could set up a special server and the box would send it's id and position to this server every time it get's a fix. Then this server could post a log entry to geocaching.com - That could also happen via some kind of sms-gateway because it's easier to send an sms than to make a data connection.

The downside is that you need some kind of pre-paid sim card.
Title: Re: My reverse geocache with nixie tubes
Post by: cowjam on Jan 04, 2011, 07:57 pm
Quote
Are you already a suspicious person in the US if you like to tinker with electronics in your spare time?


I was on the phone to my mate the other day and I was telling him about the GPRS shield I'd picked up and he said "Man that'd be great for remotely detonating a bomb!"  Hello echelon!
Title: Re: My reverse geocache with nixie tubes
Post by: liuzengqiang on Jan 05, 2011, 12:48 am
I will be darned to see terrorists use arduino-contrlled bombs on the news one day.Maybe someone's code will even be used against their good intention.
Title: Re: My reverse geocache with nixie tubes
Post by: wyager on Jan 06, 2011, 01:30 am
Very cool project... inspired me to get started on a nixie clock a few days ago. I gotta tell ya', making these things from scratch is a real challenge... After scouring over online schematics I just ordered a ton of MOSFETS, schottkys, inductors, HV caps, 25 MPSA42s, etc. from digikey only to realize that to multiplex tubes I also need HV PNP transistors.  :o
I'm also using way too many transistors, right now with my current schematic for only four tubes I'm at all 25 MPSA42s, 4 MPSA92s (anode switching), 14 general purpose switching transistors, and total of 13 IC pins just to switch the tubes (not including the pins of the ATTiny45 controlling the high voltage PSU).

Kudos to you for making a very clean, non-parts-intensive build (albeit with the help of some control ICs  :P).
Title: Re: My reverse geocache with nixie tubes
Post by: gelfling6 on Jan 06, 2011, 02:18 am
Well, from a fellow Geocacher (Yes, this is also my GC handle) I think it's cool!  I can see something like this, if the actual cache was located on the grounds of an old Nike missile site. (yet another one of my many odd hobbies)..   Yes, the terrorist have put a major dent in the hobby, but it still has its fun times..    How long does the whole thing run for, seeing only a 6V supply (or is that 4.8, Rechargable?) being boosted to 180V for the nixie tubes, must be brutal on batteries!
Title: Re: My reverse geocache with nixie tubes
Post by: wyager on Jan 06, 2011, 04:04 am
@gelfling6-
I think you'll find there are plenty of geocachers on this forum, in fact GPS is one thing that helped me to get in to arduino...
Also, a nixie tube only requires about 2mA at 170V. Assuming that he's only firing one tube at a time, that's just 340mW. Even if his driver is awfully inefficient, the draw is still probably under half a watt. Nixie tubes are actually surprisingly efficient IMO, considering the amount of light they put out.
Title: Re: My reverse geocache with nixie tubes
Post by: retrolefty on Jan 06, 2011, 04:57 am
Quote
I will be darned to see terrorists use arduino-contrlled bombs on the news one day.Maybe someone's code will even be used against their good intention.


Well they better be selective on whos code from this forum they copy. If they use any of mine, there will most likely be a few less terrorists to worry about.  ;D

Lefty
Title: Re: My reverse geocache with nixie tubes
Post by: pannen on Jan 06, 2011, 11:37 am
Quote
Very cool project... inspired me to get started on a nixie clock a few days ago. I gotta tell ya', making these things from scratch is a real challenge... After scouring over online schematics I just ordered a ton of MOSFETS, schottkys, inductors, HV caps, 25 MPSA42s, etc. from digikey only to realize that to multiplex tubes I also need HV PNP transistors.  :o
I'm also using way too many transistors, right now with my current schematic for only four tubes I'm at all 25 MPSA42s, 4 MPSA92s (anode switching), 14 general purpose switching transistors, and total of 13 IC pins just to switch the tubes (not including the pins of the ATTiny45 controlling the high voltage PSU).

Kudos to you for making a very clean, non-parts-intensive build (albeit with the help of some control ICs  :P).


I don't do any multiplexing, so I'm just using 3 anode resistors, 4 155id1 (= russian version of the SN74141) and 3 4017 binary counters. I drive them directly, because the tubes are brighter this way and I actually need less power because the firing of the tubes is pretty expensive power-wise.

I need the extra 155id1 for the decimal point on two tubes that is driven separately from the digits. I just need two outputs from that driver so I get along with two inputs. Switching on the digit one from this driver lights a decimal point before the second digit and the two is a decimal point in front of the third digit. I also could've wired the point on the first nixie, but I decided that something like .845 would look weird and 0.85 is precise enough for this application.

I also used a prebuilt power supply to get the 180 Volts (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140426808956) once I realized that you have to be very careful on placing the components on the converter to get an efficiency over 80%.

I can highly recommend this, it's not much more expansive than buying the components (Unless you order the MAX1771 that you need as a sample), it's tiny, works perfectly and can be switched off completely via the arduino.


Some comments on power:

With all three tubes lit the circuit draws 500mA and under 100mA without them. The tubes light for about 10 seconds per distance fix and it needs about 60 seconds to get the fix. So there's an average power consumption of 200mA.

The batteries (NiMH D-cells ) have 6000mAH but because of the voltage drop I'm just counting them in for 3000mAh.

That should be enough for 15hours continuous operation, or at 90 seconds per fix, 600 fixes which is enough to find the target coordinates.

[edit]
PS: This is where I got the tubes and driver ICs from: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250749058503, they also come with nice pins that you can solder to a board to make your own socket.

In case the auction is gone when you read this - this is the seller: http://shop.ebay.com/buyer.md/m.html . The tubes are called IN-12b.
[/edit]
Title: Another geocaching idea
Post by: pannen on Jan 06, 2011, 12:37 pm
As there seem to be some geocachers here - I have another idea for an arduino-powered traditional geocache.

I'd love to do this myself, but since I'm in the middle of a big city I can't find the right spot to pull this off anywhere near me where I could maintain it.


Here's the idea:

You make a plastic cache-container that can close with a servo from the inside like my reverse geocache. You'll add an arduino, some kind of display mounted in the lid and an rfid reader with the antenna on the bottom of the container. For power supply I'd add a 9V battery holder that can be accessed from the outside.

Then you hide the cachebox in a place from where you can see two distinct landmarks (a bench, some kind of tree stump, etc.). In the cache listing you'll tell the people to bring a 9V battery.

When the cacher finds the cache it won't open. They insert the 9V battery and the display says 'put me on the red mark on the bench behind you'.

There's an rfid card glued under that spot and when the cacher puts the box there the reader sees the rfid and the display says 'Put me on the treestump 200 meters north of here - you have 50 seconds... '. A countdown from 50 begins.

If the cacher does't put the box on the rfid chip in the tree stump within the 50 seconds he has to start over (put it on the bench). If he makes it the box says 'Now back to the bench, you got 45 seconds' :) and the countdown starts.

If he makes it back to the bench in time the box opens. To close it again he has to take out the battery and put it in again or put the box on a third rfid chip.

Would be real fun if you would install that somewhere where you could watch the people running around :)

You could also add more rfid stations or make them run faster.

[edit]
If you find a spot where there's something like a grid with different field on the ground (like these giant chess boards in parks) you could also make out a kind of puzzle where you have to place the box on different fields with rfids buried in them due to hints on the display. Like just displaying 'A3-D5-F3' with the chess board.
[/edit]
Title: Re: My reverse geocache with nixie tubes
Post by: Meinaart on Jan 06, 2011, 06:14 pm
Wow that's a really great idea RickP. Something to think about, and finally something useful for my bag of RFID tags I have here ;).
Title: Re: My reverse geocache with nixie tubes
Post by: Meinaart on Jan 06, 2011, 06:14 pm
BTW, great job on your project. Looks really great / professional :).
Title: Re: My reverse geocache with nixie tubes
Post by: cowjam on Jan 06, 2011, 06:52 pm
Quote
I will be darned to see terrorists use arduino-contrlled bombs on the news one day.


I don't think that's the kind of thing we get told about.
Title: Re: My reverse geocache with nixie tubes
Post by: liuzengqiang on Jan 06, 2011, 08:02 pm
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"  ;D

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.
Title: Re: My reverse geocache with nixie tubes
Post by: wyager on Jan 07, 2011, 05:22 pm
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).
Title: Re: My reverse geocache with nixie tubes
Post by: pannen on Jan 10, 2011, 05:52 pm
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  :-/
Title: Re: My reverse geocache with nixie tubes
Post by: wyager on Jan 11, 2011, 04:47 am
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.
Title: Re: My reverse geocache with nixie tubes
Post by: William_WD on Jan 11, 2011, 05:28 am
Very awesome job there :D Great concept. Congratulations :D
Title: Re: My reverse geocache with nixie tubes
Post by: TheRedGingerBaron on Jan 13, 2011, 02:27 am
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! :D
Title: Re: My reverse geocache with nixie tubes
Post by: williamanos on Jan 22, 2011, 01:53 am
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
Title: Re: My reverse geocache with nixie tubes
Post by: pannen on Jan 22, 2011, 04:21 am
Quote
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 :)

(http://i54.tinypic.com/jr673k.png)
[/edit]
Title: Re: My reverse geocache with nixie tubes
Post by: mikalhart on Jan 22, 2011, 06:58 am
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
Title: Re: My reverse geocache with nixie tubes
Post by: pannen on Jan 22, 2011, 01:54 pm
Quote
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]
Title: Re: My reverse geocache with nixie tubes
Post by: mikalhart on Jan 23, 2011, 01:51 am
Quote
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
Title: Re: My reverse geocache with nixie tubes
Post by: pannen on Jan 23, 2011, 01:42 pm
Quote

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.