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MFOS Voltage Distributor II - added assembly questione!
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author MFOS Voltage Distributor II - added assembly questione!
HeWhoWantsJeans
Hey kids,

So I've been interested in building a MFOS Voltage Distributor II for the last few days. It seems simple enough, though I have 0 experience ordering IC's. A cursory search on DigiKey for a TL084 came up with fields unknown to the people in this area (but destined to take the place of the Mudshark in your mythology) so I decided to pop in here for assistance.

A narrower search for TL084ac came up with these results. The differences between them are alien to me.

Anyone have advice on what one to order for building the Distributor?

Thanks,
Erik
Dave Kendall
Hi.

You want a THRU-hole (DIP) package for the IC. On the MFOS home page, there are a couple of pictures of ICs, in the box marked MFOS USES DIP. The difference in thepin length of the chip is easy to see.

On the page you linked to, the first and last items are in DIP packages.
There is another item a few up from the bottom that's cheaper, but is listed as "non-stock" I don't know whether that means it has to be specially ordered, or is no longer stocked (I'm eastpondian, so don't use digikey)

FWIW, the TL074 is often the same price as the 084, and I believe has slightly better specs. It's very widely used as a common quad op-amp in synth DIY, and shows up all over the place in schematics, so it may be a better bet if buying in bulk. It would certainly work fine in the MFOS unit.

In case you don't know of it yet, alldatasheet.com is a great place to find datasheets (and it's completely free - no sign up smile )

Hope this helps.

cheers,
Dave
chocolatyshatner
Man, I just went through some IC confusion ordering parts for some CGS boards. Anyway, as Dave Kendall said, look for a DIP package. When you search for TL082 at most electronics supplyers, you'll find a bunch of different numbers/letters before or after (or both) the TL082 designation. This confused the hell out of me. After looking through some data sheets trying to compare specs, I decided to screw it and go with the cheapest TL082 type DIP chip I could find lol

This is a little more diffictult when ordering CMOS chips, as you need to know if you're getting unbuffered, buffered, high-speed. . .
Luka
i would recommend buying kits from elby designs for cgs stuff
fast turnaround, well marked parts, awesome service
takes all the trouble out of it
HeWhoWantsJeans
Dave Kendall wrote:
Hi.

You want a THRU-hole (DIP) package for the IC. On the MFOS home page, there are a couple of pictures of ICs, in the box marked MFOS USES DIP. The difference in thepin length of the chip is easy to see.

On the page you linked to, the first and last items are in DIP packages.
There is another item a few up from the bottom that's cheaper, but is listed as "non-stock" I don't know whether that means it has to be specially ordered, or is no longer stocked (I'm eastpondian, so don't use digikey)

FWIW, the TL074 is often the same price as the 084, and I believe has slightly better specs. It's very widely used as a common quad op-amp in synth DIY, and shows up all over the place in schematics, so it may be a better bet if buying in bulk. It would certainly work fine in the MFOS unit.

Thanks, Dave. If I'm not mistaken, the op-amp replacement for a A-119 is a TL074 too, eh? If I can use the 074 with the MFOS Voltage Distributor, I'll just get a bunch of those.

Luka wrote:
i would recommend buying kits from elby designs for cgs stuff
fast turnaround, well marked parts, awesome service
takes all the trouble out of it

I'd be interested in that, but elby doesn't stock a MFOS kit for the Voltage Distributor. Back to the real DIY world for me.
Luka
just ask laurie at elby, he can do custom kits
he is the best kit seller that ive come across
falafelbiels
bridechamber has MFOS kits, but for this one I would just use a stripboard really.
HeWhoWantsJeans
Question: would the TL074 here fit the 14DIP socket here?

What I'd like to do is put the TL074's into a socket (to keep them extra safe from the sexy hotness of my soldering iron) on a breadboard (same thing as a stripboard, IIRC) and mount it all behind a custom plate.

Also, anyone know a good source for some damn sexy 1/8" jacks?

I know I can get the resistors and pots locally at a surplus store or two, so bam. I figure I order this stuff up, hit the bricks with FrontDesigner and we've got Buffered Mult City in the future.
Luka
you should be able to get TL074s and DIP sockets at your local store also
but to answer the question, yup socket and IC ok
HeWhoWantsJeans
Luka wrote:
you should be able to get TL074s and DIP sockets at your local store also
but to answer the question, yup socket and IC ok

Man, I wish. I work at a local electronic surplus store and we don't have any of the TL074's or the sockets. Called another one last week, no TL074's.

And man, Radioshack. Don't even get me started on them.
Luka
that sucks

you can also use TL084s

if you dont want a quad package try

tL072, tl082
HeWhoWantsJeans
So all my parts arrived, and I'm working on assembling it on a breadboard.

Looking at the schematic here, can I connect the grounds (from the mono jacks and the potentiometers) to the same ground in the 12+v circuit coming in off the bus board?

If not, where should I connect them to?

Thx thx,
Erik
fonik
HeWhoWantsJeans wrote:
Looking at the schematic here, can I connect the grounds (from the mono jacks and the potentiometers) to the same ground in the 12+v circuit coming in off the bus board?

yes, you will have to. this is your common ground (or COM).
HeWhoWantsJeans
fonik wrote:
HeWhoWantsJeans wrote:
Looking at the schematic here, can I connect the grounds (from the mono jacks and the potentiometers) to the same ground in the 12+v circuit coming in off the bus board?

yes, you will have to. this is your common ground (or COM).

Awesome.

Now I've just gotta do my COM soldering and it's done. Well, half of it.

Thanks, Fonik! thumbs up

In case anybody heard my cries of OMG, it works now. I'll be adding another and having a dual MFOS Volt. Distributor II soon.

Bam bam.
-Erik
HeWhoWantsJeans
*ump ump*

After I realized I put all the potentiometers in upside down (in relation to where the slotted part of the shaft lies), I re-soldered them all in on "unit 1".

After that was done, I decided to put in a 2nd unit on the same proto-board and using the original as a template, I'm now getting inverted voltages (ie - 9.6 neg. VDC out) from the unit across all jacks.

very frustrating

Carp. Any ideas? I'll entertain them tomorrow - after five hours on the soldering iron for today, 'tis enough.
HeWhoWantsJeans
*edited*

I chalk it up to goddamn gnomes or trolls. Seems to work now.

Just pass along, folks.
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