Bridechamber : CGS Analog Computer

andrewF

spotted this one this morning - http://www.bridechamber.com/bridechamber.com/C%20Analog%20Comp.html

very nice idea!
it looks like a combination of ASR, Pulse divider and logic gates, but what is the function of the "COMP OUT" jacks?

Rykhaard · Joined: Sep 02, 2007 Posts: 1290 Location: Canada

neandrewthal · Joined: May 11, 2007 Posts: 672 Location: Canada

Well, it says there is a gate converter on the panel so I'm assuming it's that.

mono-poly · Posted: Sat Aug 30, 2008 2:09 am Post subject:

This is a handy module!

sduck · Posted: Tue Oct 28, 2008 8:07 pm Post subject:

I bought one of the panels for this and the pcb's, and it's mostly put together now. Still waiting on some more jacks - this one takes a lot of them! A ton of wires to connect soon...

Luka · Joined: Jun 29, 2007 Posts: 1003 Location: Melb.

i am about to grab this too

is it all on one pcb sduck?
or is the just the selection of cgs pcbs?

Rykhaard · Joined: Sep 02, 2007 Posts: 1290 Location: Canada

Luka · Joined: Jun 29, 2007 Posts: 1003 Location: Melb.

it is a combination of a few cgs boards
bridechamber have a few custom cgs pcbs so was wondering

i just sent an email to scott so ill report my findings Smile

sduck · Posted: Wed Oct 29, 2008 5:52 am Post subject:

Scott is probably up to his elbows in new parenting duties, so here I go - it's on 4 pcb's. Two regular larger ones, and two tiny ones.

cgsACconst.JPG

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BananaPlug · Posted: Wed Oct 29, 2008 6:41 am Post subject:

Let us know what you think of the analog shift register. Those often are less than ideal. Typical problems: Less than instantaneous capture of the new level (slight portamento), leaky hold (voltage slowly sinks), level differences from stage to stage (e.g. one output always a little higher or lower than others). The circuit description at cgs looks pretty good.

sduck · Posted: Mon Nov 03, 2008 7:45 pm Post subject:

I'd like to let you know what I think about the asr, but that's the one part of it that doesn't work. I'm going to have to do some troubleshooting with it. My first guess is the four big caps - I was just guessing with those, and am pretty sure I've got the completely wrong kind in there (I can't remember what they are offhand). Any suggestions for what to use for these?

In the schematic, they are labeled cx - and Ken's note - "The capacitors specified as CX on the circuit board and diagram are the S&H capacitors and as such should be high quality low leakage sorts, such as polypropylene. The value of them will depend on the speed at which you intend to run the unit. The larger the capacitor, the lower the maximum speed at which it will run, but the longer it will be able to hold the voltage without drooping. 47n is probably the smallest that should be used, though drooping becomes quite noticeable at slow speeds. It may be possible to go as high as 470n for really slow operation, though this will somewhat limit the maximum speed (see the notes below). "

In other words, if anyone's gotten this to work well, what caps did you use?

eyjolv · Joined: Nov 14, 2008 Posts: 1 Location: Norway

Hi.

Luka · Joined: Jun 29, 2007 Posts: 1003 Location: Melb.

it has been mentioned that the asr is extremely sensitive to dirty power lines, perhaps separate it from you analog computer (if it isn't already) and try power it up by itself

Phillip Jeffries · Joined: Aug 23, 2008 Posts: 15 Location: Black Lodge

sduck · Posted: Sun Nov 23, 2008 12:02 pm Post subject:

Cool! Umm... - what is it? And where can I get one?

Phillip Jeffries · Joined: Aug 23, 2008 Posts: 15 Location: Black Lodge

Why its a General Purpose Analog Computer of course!

http://www.computerhistory.org/collections/accession/X42.79

sduck · Posted: Sun Nov 23, 2008 6:15 pm Post subject:

Ok. General purpose, check. Computer, check. Lots of knobs and 1/4" jacks, check. Hard to read, inscrutable labels on knobs, check. Lots and lots of blinky lights, double check. But does it handle +10v? Hmmm? And where's the clock in? Hmmm?

sduck · Posted: Thu Dec 11, 2008 7:28 am Post subject:

Ok, a follow up. The way I put mine together, it was going to be a huge pain to remove it, replace the parts, and then remember which wire went where, so I just did a complete board transplant. Bought a new pcb and parts - cost around 20$. Built it up, and then was able to do the whole replace in one sitting, so no problem with remembering wiring issues. And it works now!

I have the same issues as others have reported, namely, the voltages coming out of the various stages aren't the same as the one I'm putting in. They're pretty close, though, so it's just a matter of tuning the affected vco if that's an issue. I'm not getting drift or anything, although I haven't tried it with really slow clock speeds yet. My guess is that this is an issue with the type of caps used - they're what's storing the values, right?