[sdiy] moog module designs

[Kevin Lightner]

>
>
>All the  modules I've built (40+ different - I stopped counting after
>40) cost less than $5 a peice. The only exceptions to this were the
>power supply modules and some of the sequencer modules (8 pots at $0.41
>eats up the budget fast.)

Well I'm guessing you're not attempting to make these modules to the 
same standards of the originals. The price for the pots I use on 
Moogs cost more than $5 each. ;-)

>
>Actually the output decoupling caps was one of the areas that would
>probabily be redesigned to meet the standards of the rest of my modules.
>I know that is hearesy, but my system uses a single wire patch cable and
>current signals instead of two wire voltage signals with shielded plugs.
>I live in an area with so much radio interferance that AC coupling is
>just asking for trouble. I have had to add 10K to 100K resistors and pf
>bypass capacitors to ground on some equipment just to keep the inputs
>from picking up noise.

How does one mult things if using current instead of voltage?

>
>>  know there's some loading after them, so you may well want to be
>>  precise.
>
>. . . and this is where one of the questions of the 308 vs the 071 comes
>in. The input impediance of the 308 is 10 to 40 Megs, the 071 is much
>greater.  I thought about hanging a 10M resistor on the 071 input to
>reduce its impediance.

The bandwidth and slew rate of the 071 is higher too.

>
>>  >Another problem with the 923 is finding something to replace the SD10
>>  >noise diode. I'm probably going to go with a zener.
>>
>>  That *is* a zener in the circuit.
>>  If I could recommend, buy several zeners and do listening tests.
>
>That's good to know. My preliminary search for the SD10 hadn't come up
>with a data sheet. All my noise modules (5+) have been built with zener
>diode noise sources. I haven't built any with transistor noise sources
>yet. Is transistor noise that much better?

Zeners offer a flatter response without "spitting".
Transistors can put out bumps and peaks.
Zeners tend to provide a more predictable range when used with S/H's 
too, where notes average within a tighter band.

>
>If someone wants to donate a 308, I could do this. Otherwise it will
>have to wait till my autumn parts order.

If I donated parts everytime I was asked, I'd be out of business. ;-)

>
>
>Exactly, that was why the survey questions. In the past, I've bought
>things only to be disappointed. My first commercial computer was the TI
>99/4 for the same price I could have bought the RS color computer. I
>trusted TI more than RS. The TI ultimitley proved to be a
>disappointment. I got my first CoCo as a freebe tossed in when I bought
>a printer off a guy. It was easier to learn the CoCo then build an
>interface for the printer for the TI.

I didn't like either and used Apple II's. :)
Still have a couple and one has a promburner, 12 bit A/D card, 12 bit 
D/A card, accelerator (10mhz!), light pen, etc, etc. Which reminds 
me. Winter is over and I have to hook the sprinklers back up to the 
Apple. They're controlled using BASIC and a clock/calendar card. :)


-- 
Regards,
Kevin Lightner

Myself: http://www.synthfool.com
Service and sales: http://www.moogmusic.com/service.php
Sales: http://www.cluboftheknobs.com