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 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
Priority Keyboard
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PHOBoS



Joined: Jan 14, 2010
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Location: Moon Base
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PostPosted: Mon Apr 25, 2016 12:29 pm    Post subject: Priority Keyboard
Subject description: basic digital keyboard, can be adjusted for CV keyboard
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I just drew this up as part of a bigger circuit but it might come in handy for a lunetta controller. It's very basic, just 8 keys with a priority
encoder so if more than one key is pressed only 1 output is high. It also comes with a bonus gate output which is high when any key
is pressed. You could add some pots to the outputs (like a baby 10) to make it into an adjustable CV keyboard.

The datasheet for the CD4532 has an example on how to cascade the chips by adding 4 OR gates in case you need more than 8 keys.

edit: drew up a 16 key version as well.

-- untested --


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PHOBoS



Joined: Jan 14, 2010
Posts: 4536
Location: Moon Base
Audio files: 633

PostPosted: Wed Apr 27, 2016 5:15 am    Post subject: Re: Priority Keyboard
Subject description: basic digital keyboard, can be adjusted for CV keyboard
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PHOBoS wrote:
You could add some pots to the outputs (like a baby 10) to make it into an adjustable CV keyboard.

Since it uses a mux you could of course just use pots wired bewteen + and GND with the wipers connected to the keyoutputs
and take the CV out from pin 3.

also I guess the following schematic should work for a 16 (or larger) key version as well:


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richardc64



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PostPosted: Sat Apr 30, 2016 10:40 am    Post subject: Reply with quote  Mark this post and the followings unread

Back in the day, I used priority encoders to interface with a 32-key keyboard. I used TTL, though.

The 5-bit code the four 74LS148s (plus gates) generated went to a latch, DAC and opamps, etc. Since that worked pretty good, I built a 2nd priority+DAC board wired to the same keys, but in opposite order, so that one circuit detected the lowest note played, and the other detected the highest -- a 2-voice keyboard. (The bits of the 2nd encoder had to be inverted.) When one key at a time was played, the result was "Unison."

My less-than-virtuoso keyboarding could very often confuse the logic, though.

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dianusindustrial



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PostPosted: Wed Feb 15, 2017 12:20 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi, I've been looking to make a dead simple CV keyboard with keys that are etched like those you see in remotes:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

I understand the circuit well, but I am trying to figure out the output section. The 4051 generates 8 signals. Are these summed together to make a CV signal? The schematic for the mofos mini controller just has a singular cv output. What am I missing here?
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PHOBoS



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PostPosted: Wed Feb 15, 2017 2:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

In it's current form it doesn't produce a CV signal, it just outputs the status from the keys/switches, but because of the priority encoder
only one output can be high at a time. You could however turn it into a simple CV keyboard by a adding resistor string to what are now
labeled KEY1 OUT to KEY8 OUT and take the CV output from pin 3 of the mux.

You could also replace the switches with some (digital) inputs, hook up a bunch of oscillators and have it play by itself, this is afterall
the lunetta section. Laughing

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