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 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
Diodes on inputs and outputs?
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commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
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PostPosted: Tue Oct 21, 2014 6:35 pm    Post subject: Diodes on inputs and outputs? Reply with quote  Mark this post and the followings unread

I see this especially in PHOBoS' designs. They don't seem necessary to me, but there must be some logic to them, so what is it?
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DUBmatze



Joined: Feb 18, 2013
Posts: 150
Location: south Germaica (schwabilon)

PostPosted: Wed Oct 22, 2014 2:46 am    Post subject: Reply with quote  Mark this post and the followings unread

i start also to use that diodes... is mutch easier when you use your lunetta stuff with other (more analog) projects. (r2r Ladders or somthing) it make it easyer to add the signals (just patch 2 or more outputs to one input). so i bougth a stack of 500 1N4148 .... (somthing like 3€)

Edit: 1N not 2N

Last edited by DUBmatze on Wed Oct 22, 2014 8:27 am; edited 1 time in total
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PHOBoS



Joined: Jan 14, 2010
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PostPosted: Wed Oct 22, 2014 5:38 am    Post subject: Reply with quote  Mark this post and the followings unread

The diodes on the inputs are to protect against negative voltages. Not needed for lunetta use but can be useful
if you want to interface it with other (analog) synths. I usually only add these to CLK inputs.

The diodes on the outputs make it possible to connect multiple outputs to 1 input (as DUBmatze already mentioned).
I also place resistors on the outputs to protect against possible shorts.

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commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Wed Oct 22, 2014 7:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

So what happens if you don't have diodes on the outputs?
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PHOBoS



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PostPosted: Thu Oct 23, 2014 2:57 am    Post subject: Reply with quote  Mark this post and the followings unread

depends if you use resistors or not.

- connecting 2 outputs together without diodes or resistors will cause a short when one output is low and the other high.
Which can damage the chips.
- connecting 2 outputs together without diodes but with resistors will cause an undefined level (somewhere between Vcc/GND)
when one output is low and the other high, but it won't damage anything.

if you don't plan on connecting multiple outputs together you can leave the diodes out of course.

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http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube
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commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Thu Oct 23, 2014 8:21 am    Post subject: Reply with quote  Mark this post and the followings unread

Fantastic! Thanks guys!
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