Davo

A breadboard is a white thing with sockets for temporarily mounting parts for testing the viability of a circuit. Perfboard is a sheet of fiberglass or phenolic with holes punched and usually nothing else.

Can someone point me towards a source of positive uv-curable photoresist liquid that doesn't cost too much? I found some at http://www.injectorall.com/photoresist.htm, but those prices seem way too high compared to what I see available in the UK. I've pretty much given up on toner-transfer paper. My next project is a drying box for photoresist-made PCBs.

I can't seem to dig up a quote from Paia on their reason for using V/Hz. As it is now, the synth sounds rather flat if used for lead stuff. Adding a subharmonic generator and an LFO or two may help. I'm not sure about the 9700. I don't like its design of do-everything modules; and there are only four modules available. I've had my eye on modular synths for quite a while and Arrick (aka Synthesizers.com) looks like the best combination of price and performance. I'd like one of those with a couple modules from Blacet and/or Wiard. Wiard's Wogglebug seems especially interesting.

Not only is it cheap, but it's quite hackable. I'll have to take a pic of mine sometime. I cut out the front panel jack area and put in a piece of aluminum painted black (boy, that was an experience). On that panel I mounted five toggle switches and a pot. The pot is a 5k-ohm unit wired in series with the offset pot to allow fine control over the VCOs offset. I've applied Lee's diode mod and the CMOS 555 swap. Both combined seems worse than using just the Lee mod. The toggles are for "bandpass enable", "filter boost", "ring modulator", "hard sync", and something else. I replaced the AR/ASR with a center-off DPDT to cause the VCF to repeat itself. The output jack now has an "input level" pot in its place. All jacks were moved to the back of the optional chassis. I need to get some more parts to finish the mods, but other things have taken precedence. My only complaints about the Fatman are that the silk screening on the rack panel has a tendency to flake off and I wish that pitch-bend would do more than just one semitone. The sounds it makes are very nice. It's pretty easy for me to remember and come back to settings I like. I probably spoke to soon when I said V/Hz sounds worse.

FWIW, the Paia Fatman is a V/Hz machine and is still manufactured. In the manual this is justified by saying that V/Hz is cheaper to implement because you don't have to worry about temperature compensation. The math involved in V/Hz, however, seems hairier than in V/Oct and doesn't sound as nice.

I meant to ask what knobs or switches are required.

What additional controls are required for this filter? Does it connect only to the master core module?

Why not use a reset generator IC such as the TL7705ACP? These cost maybe forty cents apiece and are more reliable than building one from discretes.

This sounds very much like the toner-transfer process except you use acetone and a cotton ball instead of a clothes iron or laminator. How sharp are the edges when you do this? How much effort is required to remove the toner? I'll have to investigate this approach for making printed circuit boards.

That site looks good. I think I'll seriously consider them for my projects. Benefits: yes, you get a smaller board, a lot less wires, and a small mixer that mixes the four outputs to one mono output. I considered adding DIN and DOUT functionality, but that got messy. Mounting those directly behind the control panel seems cleaner anyhow.

After having a terrible time trying to get decent results from toner-transfer paper, I've decided to look into sending out to have some Quad SID boards made. Last time I posted about it, there was a decent amount of interest in it. I noticed that http://www.futurlec.com/ seems to have the best prices I've seen for small quantities. If I order ten, the price would be about $36 per board. How many of you are interested in a group buy?

Nifty! Anyone know if the sources to that are available? Can it be used as a drop-in replacement for a SID?

Note that there are two sockets on the C1 for SIDs. I'd assume then that "Monster SID" means that the SIDs can be stacked as in the Midibox SID and/or used in a superpoly mode as the Midibox SID hopefully soon will be.

Would someone please measure how high those things are so I can make sure I get the correct ones?

They're $120 for a complete kit. That gets you a board, components, 64K SRAM, two serial port pigtails, a boot floppy, and two CDs full of utilities, apps, info, docs, etc. The price includes shipping in the US. All surface-mount soldering (two qfp chips and three discretes) is already done for you. The whole NES approach also sounds viable, particularly if the second edition of the NES is used for space-saving purposes. I understand that it lacks RCA jacks, but I'm sure one can find the audio signal somewhere inside. The cartridge-based synth discussed earlier is nice and elegant, but its requirement of a TV is a big turnoff.

I think I might have a solution: a Z180 single board computer. Take a look here: (http://members.iinet.net.au/~daveb/p112/p112.html). I've made a new batch of these boards with the original designer's blessing and am selling them as complete kits. The original audience is old computer buffs, but it seems to have the kind of power and versatility you guys are talking about for controlling the 2A03.

I'm not TK, but I use gEDA for my schematics and board design. See http://www.geda.seul.org/

Well, I botched this design by forgetting to include headers to connect the DIN and DOUT modules. :P While going back to put it right, I wondered if things like the application header for the master core are really necessary. Can I get some suggestions on what other headers I should leave out of the master core section?

You don't lose anything by having the mixer, but if you don't want it, simply omit all parts related to it (numbered 5xx). You'll still need +12V if you want to use 6581 SIDs. I've found that Jameco #230535CJ is ideal for a racked midibox synth. It provides +5V for general purpose use and bipolar 12V for running my mini-mixer circuit and the FM module. +12V can be easily regulated down to +9V for running a 8580 SID. Try this in GIF: http://www.cs.csubak.edu/~dgriffi/pics/misc/quad.gif Is anyone else having trouble with that PNG image?

I'm not sure what the problem is. Are you able to view PNG images?

The board is about 240mm by 185mm. Solder-side traces are green. Jumpers wires are red. Silkscreening is white. The SID1 group has all the headers that a regular core board has. The slave groups are cut down to just what's required to be a slave group. I initially wanted to include DIN and DOUT circuitry, but decided that building them on the same perfboard that I mount the front panel stuff would be cleaner and save space. Each SID group is capable of using either a +9V or +12V SID. This is selected with a jumper just north of the SID. In practice, it would be safer to solder a wire jumper into place rather than risk having a shorting block fall off and possibly get put back wrong. The mixer unit requires +12V and -12V and provides a mono output. As the board is now, all these voltages must be supplied externally. I'm tinkering with making it accept +12V and regulate it down to +9V and +5, and somehow get it inverted for -12V. Perhaps that might introduce noise. A seperate regulator board between a +12V power supply may be a cleaner approach. Advice? Opinions?

I've almost completed design on a quad SID board. This incorporates four core and SID modules onto one single-sided board along with a simple four-channel mixer (to give a mono output composed of all the SIDs). Yes, there are jumpers. Would anyone here be interested in trying out the foil pattern? Another question, for you, TK. What license do the Midibox schematics fall under? So far, it seems to be BSD-ish with GPL for MIOS and its applications. What license would be appropriate for this board I'm making. FWIW, I have absolutely no plans whatsoever to make and sell these boards, though SmashTV is free do so as far as I'm concerned.

So, if you can't use shielded cable, how about twisting a ground wire around each signal wire? Perhaps try flat speaker wire?

Because voltage determines pitch, envelope, gate, velocity, etc; CVs are inherently monophonic. You can get polyphony using CVs, but you must manually set up each additional voice. Peruse http://www.synthesizers.com and you'll find more in-depth discussion of what CV is and how it's used. If you're thinking about running the output of, say, and MBSID through a Moog-style ladder filter, you need at least one CV channel to control the filter. Then you can run whatever audio signal you want through the filter.

Can you point me to a photo of the unit in question? I think I might have some of the switches you want (got them from Jameco).