Dec182010

Kit building: vacuum fluorescent display clock

Published by paul at 2:51 PM under Kit Building | VFD

I've always been intrigued by vacuum fluorescent displays (VFDs) so I picked up the Ice Tube Clock Kit from AdaFruit Industries that uses a Russian VFD tube.

(Click any photo for a 1024x768 image.)

Here's what came in the kit:

 

And here are a couple of shots of the VFD tube. It has 8 x 7-segment digits, with decimal points and a minus sign.

 

There's a great page on AdaFruit's website that describes the circuit and the calculations that went into designing it - check it out!

The building instructions are very thorough, as always, and this time includes test points as building progresses. On the left is a shot of testing the 7805 regulator, and on the right is testing the voltage booster circuit for the VFD.

 

Once I had the main board made, it was time to thread the VFD into it's PCB. This was a finnicky task but with patience it only took 15 minutes. The leads from the VFD bend very easily, which is a blessing and a curse. On the left you can see what I mean, and on the right I've got it ready to solder.

 

And here's it soldered and nicely clipped.

 

Did a quick test and it worked! Then I put in the final few components on the main board and assembled the laser-cut perspex case.

Here are a couple of shots of the completed main PCB:

 

 

And the clock itself... and in it's final resting place.

 

Hope you enjoyed the photos - let me know if these kinds of posts are interesting!



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Oct022010

Kit building: Four interactive light panels connected together

Published by paul at 7:24 AM under Kit Building | LED Projects

Well, summer's over and that means I can justify being indoors playing with (and blogging about) electronics again. Expect this blog to get busy again!

Back in March I blogged about building an interactive light panel from Evil Mad Science Laboratories. Over the summer I built the other three light panel kits I'd ordered and finally got around to hooking them together and testing them out.

They fit together using 8-pin connectors in any configuration imaginable. Below are two photos of the connectors (borrowed from their website):

 

Below are three photos showing my four panels in a variety of configurations (click for larger versions):

 

 

Finally, I shot some short videos showing the 1 x 4 configuration in action:

Next up will be some more Arduino stuff...



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Mar122010

Kit building: Evil Mad Science interactive light board

Published by paul at 12:53 PM under Kit Building | LED Projects

It's been another few weeks of traveling and client work so I haven't had any chance to tinker. Apologies to those subscribers expecting the frenetic pace of my SQL blog - ain't gonna happen. I'm at home for a few weeks now though, so should have spare cycles to get back to the Arduino.

This week I decided to build a kit, as I didn't have time to get stuck into something more intellectually challenging. A while ago I'd ordered a set of 4 interactive light panel kits from Evil Mad Science so I chose to make one of those (I've also got an RGB Peggy 2 board that I'm itching to make!).

I'm very impressed with the kit - the instructions are *excellent* - totally suitable for a novice, but easily digestable by someone more advanced without being annoyingly simple. The packaging is great too - with all components packed and labeled separately - not something I expect, but a nice time saver.

The kit took me about 4 hours of soldering and neat lead-snipping to put together. I powered it on and it worked first time. However, it's supposed to work in the dark and I couldn't get anything out of it. The board looked perfectly put together so I contacted Evil Mad Science. Windell replied within 90 minutes with some suggestions. I replied that I've got a degree in electronics so talk techie - smileys ensued and we troubleshooted (troubleshot?). I'd hooked up a spare IR LED and shown that the phototransistors were working, but obviously the IR LEDs on the board weren't - with only about 10mV foward voltage across each. The whole IR LED circuit has 24V through it, so something was sucking down the power. I traced it to a broken IR LED with very high resistance both ways, and taking 18V - no wonder it wasn't working. I swapped out the broken LED and put in another, and hey presto! Great technical support!

Great kit to put together and I'm going to build a wall tile to hang in the house somewhere!

Here's a link to a 25sec video I shot on YouTube: http://www.youtube.com/watch?v=51dUYjEgTi8

Here are some photos (click for larger images):

Left: kit contents for one board. Right: PCB (*really* well produced).

 

Left: ready to start soldering. Right: Completed board ready for testing.

 



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Jan252010

Kit building: Hansen Hobbies mini-scrolling LED sign kit

Published by paul at 2:30 PM under Kit Building | LED matrix

Over the weekend I found some time to solder together a kit that I'd picked up before getting stuck into the Arduino. It's the mini-scrolling LED sign kit from Hansen Hobbies and seems to be the only non-RC kit they make. It's a really nice kit that's fun to put together and at $40 it's not too expensive.

The finished kit produces an 24x8 red-LED display, using three 8x8 LED matrices. The LEDs are driven from the PIC16F628A microcontroller through three 74AC164 shift registers and eight PN2222A NPN transistors, with the transistors switching power to the rows of the matrices and the shift registers controlling the columns. The kit comes with comprehensive instructions and explanations of the circuit operation. Nicely done overall.

Here are some photos of the build process (click the image for a larger version):

1) The kit contents (I'd already started soldering when I realized I'd forgotten to take the initial photo)

 

2) Finished with passive components. One of the resistors broke so I substituted one I had lying around - can you guess which one? :-)

  

3) Finished with everything except the LED matrices. The components are packed in tight and the solder pads are very small - making for a few tricky soldering moments.

  

4) Everything in place. The LED matrices required some jiggling to get in - quite a few tiny movements to the pins with needle-nose pliers to get them to slot into the tiny through-holes. The PCB is very well put together with the shift register ICs on the underside from everything else to save space.

  

Everything worked on the first test! The four micro-tact switches control the editing of the message (all ASCII characters are there) and the message scrolling speed (8 speeds from stopped to blur). You can also connect the board up to a PC using RS232 or directly to another microcontroller - pretty neat.

The PIC is programmed with a 'well done' message that displays until you put in your own. Below is a video of the first one I entered (click to play).

 

Next up - using transistors with the Arduino to multiplex LED 10-bar arrays - eventually working up to designing and building my own scrolling sign using the Arduino, and beyond!



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Jan172010

Kit building: Mod Amp Kits guitar reverb pedal

Published by paul at 5:11 PM under Kit Building | Audio

My 8-year old daughter started learning to play the electric guitar in September and that gave me an idea for one of the first kits to make to brush up my soldering skills. I'm using a Weller WD1001 soldering station which is light-years better than the old unregulated soldering irons I used to use 15 years ago in the UK. I made a couple of little light-following bugs (the MK129 and MK127 - the MK127 has much better movement) and then a reverb module from Build Your Own Clone (BYOC). It had a nice PCB but when I made it there was a weird short-circuit I couldn't figure out on Christmas Eve in time to wrap it up for a present the next day (all three pins of the 78L05 regulator gave 9v!!) so decided to try another brand.

I settled on the The Verb kit from Mod Amp Kits. It uses the Belton BTDR-1 DigiLog Reverb module (here's the PDF datasheet) and has a cool green box that my daughter thinks is groovy. The kit circuit is pretty simple but I'd failed to notice that it's not PCB based - it's all built using tag strips - aaarrgh! I find tag strips *really* annoying to solder on, and this kit is especially finicky as the instructions call for the tag strips to be mounted inside the box and then the components soldered in, however the instructions are excellent and everything went to plan - the kit is very well designed and I'd recommend it.

The following photos show the build process at various steps so anyone else building this can see what it's supposed to look like. Click the image for a 1024x768 blow-up.

1) Here are the contents of the kit. There's also a printed assembly manual and the case. The manual for this kit is much better than the BYOC kit.

 

2) End of Section 1 (Drawing 2 in the manual). Note that the footswitch must be mounted with the lugs horizontally, but it doesn't matter which way up. It's a 3PDT (three-pole, double-throw) switch. The BYOC kit didn't explain this, so I wasted a bunch of time figuring out how the switch worked. Notice how close the tag strips come to the input and output jacks. I had to do some tag bending to make sure there were no short-circuits. Everything's very close together, and the box gets very crowded (as we'll see below) so I wouldn't recommend this for soldering beginners.

 

3) End of Section 2 (Drawing 3 in the manual). I liked their idea to use sleeving from the hook-up wire to insulate the unused pins on the reverb module, but it left me a little short of wire in the final stage - luckily I had some of the same color and gauge lying around (couldn't possibly have multi-colored hook-up wire inside the box - very untidy :-)

  

4) End of Sections 3 (Drawing 4) and 4 (Drawing 5). Drawing 5 doesn't give a simple representation of the footswitch wiring. Pay attention to the last line of paragraph 3 in Section 3 - I misread and soldered it - and then had to unsolder again when I realized more wires would connect to log 3 of the pot.

 

5) End of Section 5 (Drawing 5). I ended up mounting the reverb module as soon as I could to get it out the way of everything else.

  

6) Working through Section 6 (Drawing 6). Although the soldering order given in the manual is pretty good, I found it better to slightly reorder how I did things for easier access to the terminals as I went along. I also worked out how to layer the components vertically so I could solder them individually rather than trying to have 4 components balanced inside the box an solder them all at once - almost impossible. Pay particular attention to the orientation of the two transistors - they're both soldered gate-source-drain left-to-right. The images show the progression through the terminal wiring. You can see a few little nicks in the insulation on two of the wires in the right-hand of the box - testament to how closely packed everything is.

  

 

7) End of sections 6 and 7 (Drawing 6). Not quite as tidy as the image on their website but I was very pleased with my handiwork!

 

8) The finished unit from the outside.

 

Total build time was around 6 hours. We tried it out last weekend and it worked perfectly first time!

Enjoy!



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