Passive Box (maybe a little guidance is in order)

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rimbod
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Passive Box (maybe a little guidance is in order)

Post by rimbod » Tue Mar 28, 2017 7:41 am

Hi folks. Venturing into my first uber-simple DIY project. Making a box of passive utilities to use with my eurorack synth. The box has three sections. The theory behind each of the three sections is so simple, though, that I'm afraid that I'm succumbing to my own "troll physics."

The first section is a SPDT switch, intended to toggle one input between two outputs, and vice versa.

It seems self-evident that, if wired as indicated, I could take an input from the jack on the right and toggle between the two outputs on the left. (and potentially vice versa?)

Image

I'm willing to be wrong. I'm willing to require more parts. I'm not made of glass, so please let me know what you think, even if I'm being unbelievably ignorant.

But shouldn't this work? I'm using the following parts:

SPDT
http://akizukidenshi.com/download/1MS1T1B1M1QN.pdf
Kobiconn 3.5 inch jack
http://www.mouser.com/ds/2/449/KC-300411-202203.pdf
Last edited by rimbod on Tue Mar 28, 2017 8:12 am, edited 2 times in total.

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Post by keninverse » Tue Mar 28, 2017 7:46 am

Yep, this will work and it is bidirectional. A multimeter set to continuity test would be of a lot of benefit in this situation. If you have one available set it it to continuity test (which sometimes looks like a radio signal) and test each switch position.

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Post by rimbod » Tue Mar 28, 2017 7:56 am

Here goes the second section I think I may be being silly about. It's a bunch of one-input two-output mults.

It's based on this document: http://www.megaohmaudio.com/images/PassiveAttMult1.pdf

Image

They're the same Kobiconn jacks as before.
Last edited by rimbod on Tue Mar 28, 2017 8:10 am, edited 2 times in total.

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Post by rimbod » Tue Mar 28, 2017 8:00 am

The last section is based on the same document as in the second section. It's passive attenuators.

Image

As we are viewing things from the back, the input is on the right and the output is on the left.

Same Kobiconn jacks as above.
These are the attenuators:
http://akizukidenshi.com/download/Supertech_vr.pdf
They are 50K, as per recommendations from different threads on MW.

Thanks in advance for any advice you can give me, even it it's a simple confirmation or a lengthy explanation of how this shouldn't work.

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Post by rimbod » Tue Mar 28, 2017 8:02 am

keninverse wrote:Yep, this will work and it is bidirectional. A multimeter set to continuity test would be of a lot of benefit in this situation. If you have one available set it it to continuity test (which sometimes looks like a radio signal) and test each switch position.
Thank you. I'm going to be having my industrial arts teacher friend helping me out, and one of the things I'll be having him teach me is how to use/read a multimeter.

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Post by rimbod » Tue Mar 28, 2017 9:57 pm

Here's a photo for context.
Image
Huh, it came in sideways. Weird.

So yeah. A lot of repetitive soldering.

If someone could comment on the other two wiring diagrams, I'd appreciate it.

Also, as a beginner, I'm a bit concerned about holding the soldering iron to the parts too long and rendering them useless. Is this a reasonable concern? I plan on using a 30 watt iron.

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Post by ClausF » Wed Mar 29, 2017 2:18 am

All three circuits should work as expected, and all three are bi-directional.
Anywway, as someone before said: best for you to discover these things (and how switches work or how the switch on the jacks works etc. etc.) would be a mulitimeter. $20 from Amazon is ok, but look that it has a beep (an acustical sign if there's connection or not).

Anyway: I would connect all GNDs of all Jacks (like a metal faceplate), so you don't have to think about that anymore..

At the end a useful box....

And: check the Doepfer DIY page, that helps a lot: http://www.doepfer.de/DIY/a100_diy.htm

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Post by rimbod » Wed Mar 29, 2017 3:48 am

ClausF wrote:All three circuits should work as expected, and all three are bi-directional.
Phew! Thank you.
ClausF wrote:Anyway: I would connect all GNDs of all Jacks (like a metal faceplate), so you don't have to think about that anymore..
I've seen in other threads people connecting all the grounds to one another. You suggest a separate piece of conductive metal?

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Post by ClausF » Wed Mar 29, 2017 4:35 am

no, if I have a row of Jacks I use the residue wire of resitors for example and connect all the grounds with that (and a bit of solder). Or silver(ed) wire, that is used for jewellery and pretty cheap

And your jacks are pretty in row, just connect the grounds in the row, then connect the rows, and there you are, one big GND... At the end it's not better then your concept, it just keeps all the GND away from your thinking and you can concentrate on the signal flow.

I do it that way on modules, small (Lunetta) synths etc...

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Post by rimbod » Wed Mar 29, 2017 10:33 am

ClausF wrote:no, if I have a row of Jacks I use the residue wire of resitors for example and connect all the grounds with that (and a bit of solder). Or silver(ed) wire, that is used for jewellery and pretty cheap

And your jacks are pretty in row, just connect the grounds in the row, then connect the rows, and there you are, one big GND.
I'll keep that in mind. My soldering skill is fairly low, so I'm gonna just connect the grounds together for now. If there is a problem, though, I'll definitely follow your suggestion.

BTW, I did a prototype of the switch circuit, and it works! Hooray, electrons!

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Post by keninverse » Wed Mar 29, 2017 10:56 am

Just get some 20-24AWG bare tinned copper buss wire.

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Post by controlFreak » Wed Mar 29, 2017 12:26 pm

With separate grounds you are less likely to run into funky interactions between unrelated circuits.

Good luck with your build!

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Post by snercle » Wed Mar 29, 2017 8:00 pm

Those switches can get a bit hot if you spend too long with the iron on them, so be sure to save them til last. Also be aware that passive multis won't stop the sources of your inputs from interfering with each other, which won't damage anything but sometimes one signal can overpower the other or change the behaviour of the source.
I tend to connect every ground, that way you know you can plug in external sources without losing ground reference.
If you're a guitar player you can use an old guitar string as ground bus wire.
Looks like fun.

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Post by rimbod » Thu Mar 30, 2017 2:11 am

Wired up and tested all the switches. That's one thing down! I did that before the advice rolled in to do them last... but they all worked just fine when I tested them!

For now I'm just connecting all the grounds in a single unit, like all the grounds from the jacks in one switch are connected with one another and not to those of other switches. I figured that would minimize cross-interference between switches, if that's a thing. I may go back and do the guitar string thing later, though, if problems arise.

I'll post pics after the whole thing's done. Tomorrow I'll be doing the mults if I have time.

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Post by rimbod » Tue Apr 04, 2017 2:07 am

Wired up the mults and attenuators today. It took some time, but it was really easy! I'll upload a picture when my phone isn't being so much of a jerk.

I was really surprised to find virtually no voltage drop when two outputs are writed out of the mults. I believe it was Heterodyne who first recommended me to build a ton of passive utilities, and I thank him for that.

If someone wants clear wiring diagrams and doesn't have much of a background in electronics diy, please feel free to direct them to the photos I uploaded above. Excellent soldering practice and easily achieved.

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Post by nigel » Tue Apr 04, 2017 8:02 am

ClausF wrote:All three circuits should work as expected, and all three are bi-directional.
NOT the attenuators! Feeding a signal into the output jack (instead of the input jack) will short it to ground if the attenuator is turned all the way down. (It's unlikely to break anything, but it can have undesirable effects.)

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Post by ClausF » Tue Apr 04, 2017 9:00 am

Yep, your right, nigel. Was not aware of that, but after painting it and thinking about it... :bang:

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Post by rimbod » Thu Apr 06, 2017 7:35 am

nigel wrote:NOT the attenuators!
I kindof had a feeling that was true, but now I know why. Thank you!

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Post by rimbod » Fri Apr 07, 2017 2:56 am

Here ya go. Not the prettiest job, but it works well and I like the outside look.

Image
Image
Huh, second one came in sideways again. Whatever.

I'll upload another photo (not sideways) when I work it into a solid patch.

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Post by rimbod » Mon Oct 16, 2017 12:18 am

I don't mean to draw attention to myself, but holy crow this box has turned out to be intensely useful.

I'd like to encourage folks to use this project as a way to get into soldering and figuring out how to use passive utilities in their rig.

Peace:)

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Post by Navs » Mon Oct 16, 2017 1:30 am

Well done! :tu:

Switches are great.

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Post by FetidEye » Mon Oct 16, 2017 6:53 am

your wiring looks like an artwork! (hang it on the wall!)

cool :sb:

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Post by ClausF » Mon Oct 16, 2017 7:36 am

rimbod wrote:I don't mean to draw attention to myself, but holy crow this box has turned out to be intensely useful.
I'd like to encourage folks to use this project as a way to get into soldering and figuring out how to use passive utilities in their rig.
Peace:)
Absolutely, this is very useful and a very cool and simple first soldering project... :guinness:

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Post by rimbod » Tue Sep 17, 2019 12:02 am

Hey. Gonna make one of those switches in a four-hole 1U pulp logic panel. Will report back with pix.

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Post by rimbod » Tue Sep 17, 2019 3:44 am

Oh darn. Help plz.

So this is the back...
Image

And this is the front...
Image

And it's only throwing to the light brown wire (the black cable) no matter which direction the switch is.

This is what I get for not keeping up with soldering, but I plan to do a _lot_ over the next two weeks, so you might understand how this might feel discouraging.

Aside from my feeble human emotions, tho, what do you think has gone wrong?

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