Adafruit “Ice Tube” clock kit — build log

First of all, you can get the KIT here! It may be out of stock, but that is a different story ;-)

3954072899_8abd2149f2_o

These 3 pictures show the output voltage of the onboard open loop step-up converter. The voltage base line for the big image is the first div separator from the bottom. The amplification is set to 10V/div. In the 2nd and third image the timebase is set to 5µs/div and 100ns/div, the amplification to 10mV/div.

3954865348_73378cb483_o

3954084573_bfd84da4d3_o

3954865584_3675116cea_o

When testing it for the very first time it delivered 55.2V DC with only about 40mV of ripple. I haven’t checked if the ripple’s frequency ( about 250kHz ) corresponds to the driving voltage that is fed to the FET. The HF ripple has a frequency of about 15MHz and is way faster than what the ATmega168 should use to drive the boost converter.

All the parts:

3954084081_d02f7cefc6_o

3954078509_567c5afb5e_o

Populating the main PCB:

3954080439_714e690949_o

The backup battery needs a small blob of solder to get good contact with the board. Also the battery clip must be put on before the diode.

3954084327_02d14c24bc_o

Too much solder will block the battery, so don’t ;-)

3954859192_9bb7c36320_o

Hooking up the VFD tube:

3954854794_87e6c52a7e_o

If you cut the tube’s wires like this, you’ll have almost no trouble inserting it into the PCB.

3954076079_b72bdba0d1_o

Aligning the VFD tube, so it fits well ( flush with the left cover ) :

3954074237_ae61cb0b0c_o

Boxing the clock:

3954856284_ca38f4c568_o

The assumed spare pair of nuts is used as spacers for the main PCB, so don’t repurpose them before you’re done with the KIT. The bottom cover also contains a short manual – sneaky.

3954071121_e36ce3860c_o

Some of the nuts must be hacked, so they fit perfectlly:

3954072031_fcb8a164b7_o

The finished thing:

3954852924_4dfdf9a2b2_o

3958491751_e78c277e52_o

The acrylic is very prone to finger prints, so make sure you’ve cleaned the pieces before you assemble the box!

The clock is quite easy to build, but needs some care nevertheless. Especially the vacuum fluorescence tube is easily hurt. For one thing it is made of glass. Also the wires coming out of it don’t seem to like being bent to often. The rest is simple. If you’ve built a boarduino DIY KIT or similar, you won’t have any problems with it.

All pictures of the build can be found in the flickr set. The clock’s home page with assembly instructions and firmware download is here. In case you need it and don’t want to poke around in the Makefile, the fuse and lock-bit settings for the ATmega168 chip are: lfuse: 0xE2, hfuse: 0xC6, efuse: 0x01, lock: 0x3F. Programming the chip using the ICSP connector only works after removing the VFD driver and backup battery. Otherwise the programmer can’t talk to the chip properly.

Here are some IV-18 clocks, that look quite similar to this one:

Update 1: 22.10.2009:

I and others have had problems with the clock resetting randomly when buttons were pressed. It turns out that this was caused by nested interrupts due to switch bouncing. Each time the ISR gets called some registers, and more importantly a return address, are pushed onto the stack until it runs out of memory and all goes bad.

Memory Areas and Using malloc():

During interrupts and subroutine calls, the return address Program Counter (PC) is stored on the
Stack. The Stack is effectively allocated in the general data SRAM, and consequently the Stack
size is only limited by the total SRAM size and the usage of the SRAM…

Nesting can be avoided by disabling the interrupts inside the ISR. Now the interrupt cannot occur anymore while the handler is running. All the resets are gone !

This is based on this post.

This entry was posted in Electronics. and tagged , , , . Bookmark the permalink.

5 Responses to Adafruit “Ice Tube” clock kit — build log

  1. Helmut says:

    Kennt dein Prof. deinen Blog? :-)

  2. robert says:

    Heute ist Samstag. Ausserdem ist es bestimmt nicht kontraproduktiv sich ausserhalb der normalen Bürozeiten anderweitig geistig zu stimulieren. Erhaltung des Wohlbefindens, seelische Balance usw.

  3. Helmut says:

    Wenn es der “Wahrheitsfindung” dient. :-)

  4. robert says:

    Eben nicht!

    Ein Bratwurstverkäufer will zum Mittagessen sicherlich auch was anderes als gerade Bratwurst.

  5. Helmut says:

    Du hast mich voellig missverstanden.
    Ich wollte ausdruecken, dass Entspannung ausserhalb der “Buerozeiten”
    effizienzsteigernd sein kann.:-)

Comments are closed.