SynthFrog » side projects

Sowing the SIDs of love

aris — Fri, 13 Mar 2009 07:53:00 +0000

All things come to those who wait. But even if you wait for an eternity, no SID will come your way unless you hunt it down because it has been long since it was discontinued! And so I did hunt it!!. Two found and thus, the quest for the MidiBox SID began.

It is a stereo SID synth. Two sids, one for each channel. Made the Core (the old 8 bit), got two 18f4685 (of which I toasted one because I gave it 12 volts!! Thank god I got two) made the boards and TADAAA!!!!

The SID works!! If you play something via midi you get a square lead sound.. nothing special but it is there.. So now I must add buttons and encoders.

The only thing that went wrong apart from the burnt PIC was that the 20×4 blue/white screen I had to put , went cookoo!! Maybe this was a result of the 12 volt jolt! But, no real harm done since I have a spare 40×2 screen.!!

Now I REALLY have to finish the midibox router and midibox sequencer.. I have no excuse, neither does Braska!!

Side projects

aris — Thu, 23 Oct 2008 10:23:00 +0000

This is an octal RGB clock. I made it so it can be impossible to actually tell the time but nevertheless its beautiful (in its own way).

There is an atmel AtMega8 µCU and 6 RGB leds. Two for hours, two for minutes and two for seconds.

Each led can be Red, Green, Blue, or a combination of them. So you get eight colors, Red, Green , Blue, Magenta, Cyan, Yellow, White and Black (all off)

Lets say now that a led (with all its colours) is a binary number and Red is bit 0 (rightmost), Green is bit 1 and Blue is bit 2. With the above combinations you get a number between 0 and 7 (hence the octal part) . Two leds can count up to 64 this way. So you can count easily up to 60 seconds (and minutes)

eg: the time on the second photo is:

Red, Cyan : Green Cyan : Red Green=
1×8 + 6 : 2×8 + 6 : 1×8 + 2 =
14:22:10

Nice eh?

(wouldn’t sell though : )

Making of the UV Oven

aris — Thu, 23 Oct 2008 09:40:00 +0000

To start, I had to make the array permanent and to such dimensions so as to have even lighting all over the surface of a typical photo-resistive PCB. So I laid them as shown, taking into account the distance of the leds which was enough to have overlaping beams of all leds. (so no blind spots where created) .

This was put in a ikea FIRA box, slightly modded for the purpose. (I left only the bottom drawer, didnt put the mid panels and used one of the mid panels as a swing door, attached to the top of the box with safety belt ribbon, glued and stapled to the box and door)

The first test consisted of burning two photoresistive boards with components needed to make MIDIBOX sequencer v3.3 . It was a total success. as it can be clearly be seen.

Before going into burning the midibox sets , I performed some tests. The results were as such.

* With the current setup (35 UV leds (UV =395nm) at about 20mA each from a distance of around 30cm) the board needed around 15 minutes to be developed
* Reasonable results were between 10 and 20 minutes
* The film used was simple inkjet transparency but I would print it TWICE (my printer is accurate enough) or use two printed transparencies one on top of the other

They were then developed using the standard procedures (NaOH in water for removing excess photo resist and then FeCl3 or Sodium persulfate or whatever you are used to)

The results were AMAZING. The Oven was (and still is) one of the most important tools in my “lab”. (The timer was dumped, I had a watch and pulled the plug)

PS. The array of leds needed quite a lot of current/voltage and I was lucky to find a hewlett-packard printer transformer with 1A/37V output.. Don’t test THAT with your tongue!

Board oven timer

aris — Thu, 23 Oct 2008 09:03:00 +0000

Not exactly synth-DIY but this is a timer I made for my soon-to-post PCB oven. You just set the time and keeps track of it, switching it off when it must and securing it from accidentaly opening the lid, saving my eyes from UV burn

Training day (night)

aris — Thu, 23 Oct 2008 08:46:00 +0000

Got a PIC (microchip.com) programmer off ebay (I wonder what I would do without ebay here is its anthem).

It is a el-cheapo clone, (cheapest USB programmer I found) able to programm only 8-bit microchip.com microcontrollers (such as the 16f84 and 16f877 and 18f452 that the good guys at microchip.com sent me as samples). I tried almost every language available for them (like picBasic pro etc) but settled for microchip’s own compilers (namely C18) which also comes in an educational edition that has optimizations disabled. No problem there. Since my C background is much better than Assembly, I felt right at home