OR what ?

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mousegarden
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OR what ?

Post by mousegarden » Fri Jun 17, 2016 4:10 am

This is me all over, I'm thinking of getting an OR module, but don't know exactly what it is ! The concept still mystifies me, a succinct explanation would suffice, so that when I do get one I'll know what to with it ! But I feel I should have one OR two :hmm: :oops:

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flo
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Post by flo » Fri Jun 17, 2016 4:41 am

There are two types of logic modules, binary and "continuous" ones (fuzzy logic). The latter always also does the former.

To wrap your head around the binary functions, truth tables are rather helpful:

Image

So, OR only returns 0 if both inputs are 0.

In continuous fuzzy logic, AND always returns the minimum of all values, OR returns the maximum (they're often called MAX/MIN on modules, e.g. the Doepfer A172). The negation is 1 minus the value (if values are expressed between 0 and 1). You'll see that these formulae also hold true for the binary implementation.

Tons of fun things you can do with either variant. Logic is great! :hihi:

Cheers :guinness:

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fac
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Post by fac » Fri Jun 17, 2016 6:58 am

You can see an OR module as a gate signal mixer. You have two gate signals as inputs and a gate signal as output. Whenever either of the two input gates goes high, the output goes high. When *both* inputs go low, the output goes low. That's it.

In contrast, an AND module would be like a gate chainer. If both inputs are high, the output goes high. If either input goes low, the output goes low. It's just as if you placed one gate after another gate.

BTW.- Don't just buy an OR module. Buy a logic module with multiple operations (AND/OR/XOR/NOT) so you can "mix" logic/gate signals in different ways.

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CMOSCrash
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Post by CMOSCrash » Fri Jun 17, 2016 8:36 am

Is my understanding correct that you have to use an OR gate to mix trigger/gate signals, and that a simple "multiples" module is not to be used to combine gates, as it would be connecting two "outs" together? And rather than integrated "OR" gates, a simple diode to prevent reverse current flow would be acceptable for an OR mixer, correct?

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flo
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Post by flo » Fri Jun 17, 2016 9:03 am

Yes. Do not mix with mults!

Generally, you can also just use a normal mixer to combine triggers / gates...

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Post by nuromantix » Fri Jun 17, 2016 12:47 pm

You can always use a VCA as an OR.
EDIT: NO YOU CAN'T….. i was half asleep

Alternatively, you can use a MakeNoise Maths if you have one.
If you don't then you should get one because it's very interesting ;)
Last edited by nuromantix on Sat Jun 18, 2016 1:36 am, edited 1 time in total.

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Post by vlk » Fri Jun 17, 2016 2:05 pm

nuromantix wrote:You can always use a VCA as an OR.
I think a vca does AND logic, no?

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Post by cheliosheart » Fri Jun 17, 2016 2:06 pm

vlk wrote:
nuromantix wrote:You can always use a VCA as an OR.
I think a vca does AND logic, no?
That's what I thought too.
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Post by unrecordings » Fri Jun 17, 2016 2:16 pm

OR you can very simply make one with some diodes

From the excellent Doepfer DIY page:
http://www.doepfer.de/DIY/a100_diy.htm

Image

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strangegravity
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Post by strangegravity » Fri Jun 17, 2016 2:54 pm

cheliosheart wrote:
vlk wrote:
nuromantix wrote:You can always use a VCA as an OR.
I think a vca does AND logic, no?
That's what I thought too.
No, a VCA opens on the gate signal regardless of the source signal. It may seem like an AND because most VCAs will pass the source signal in the absence of a CV plug. This is just a hardware function that bypasses the VCA if there is no plug in the CV jack.

So you could have silence on your source patch but the VCA gate will still open on a CV signal.

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Post by daverj » Fri Jun 17, 2016 3:02 pm

The key is in the name, and simply understanding the English definitions for the words "or" and "and".

The logic is based on the idea that a signal goes positive (high) to make something happen. Like a trigger or a gate. If you have more than one signal then you can combine two of them so that if one goes high OR the other goes high, the output goes high. An alternate way of combining them is that if one is high AND the other is high then the output is high.

So an OR gate puts out a high signal if either of it's inputs goes high, while an AND gate requires them both to go high or it won't put out a high signal.

The OR gate can be used like a mixer to combine two gates or triggers and let both of them through. The AND gate can be used to have one block the other, so only if both signals exist will the output gate or trigger something.

An "analog OR" and an "analog AND" follow similar kinds of thinking, but happen with analog waveforms, and the inputs and outputs have continuously changing voltages. With an analog OR the output is the highest voltage of the two inputs at any given instant in time. If input 1 reaches a specific voltage OR input 2 reaches a specific voltage, the output will be that voltage.

An analog AND puts out the highest voltage that input 1 AND input 2 have in common. So that is in fact the lowest of the two voltages. A common analog AND/OR module is also known as a MIN/MAX module.

With both of these it's also just as simple as understanding the definition of the English word "or" and "and", but since it is an analog version instead of digital you aren't simply comparing the existence of one signal vs another. Now you have to compare the voltage levels of one vs the other.

So with analog OR you think: if input 1 is 10v OR input 2 is 10v then the output is 10v, otherwise if input 1 is 9v OR input 2 is 9v then the output is 9v, otherwise if input 1 is 8v OR input 2 is 8v then the out is 8v, etc......

With analog AND you think similarly: if one input is 10v AND the other input is at least 10v then the output is 10v, otherwise if one input is 9v AND the other input is at least 9v then the output is 9v, otherwise if one input is 8v AND the other input is at least 8v then the output is 8v......

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Post by Rigo » Fri Jun 17, 2016 3:19 pm

strangegravity wrote:
cheliosheart wrote:
vlk wrote:
nuromantix wrote:You can always use a VCA as an OR.
I think a vca does AND logic, no?
That's what I thought too.
No, a VCA opens on the gate signal regardless of the source signal. It may seem like an AND because most VCAs will pass the source signal in the absence of a CV plug. This is just a hardware function that bypasses the VCA if there is no plug in the CV jack.

So you could have silence on your source patch but the VCA gate will still open on a CV signal.
You will only get a signal out of the VCA if the CV is high and there is an actual signal on the input. I call that an AND ...

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Post by cheliosheart » Fri Jun 17, 2016 3:35 pm

Rigo wrote:
strangegravity wrote:
cheliosheart wrote:
vlk wrote:
nuromantix wrote:You can always use a VCA as an OR.
I think a vca does AND logic, no?
That's what I thought too.
No, a VCA opens on the gate signal regardless of the source signal. It may seem like an AND because most VCAs will pass the source signal in the absence of a CV plug. This is just a hardware function that bypasses the VCA if there is no plug in the CV jack.

So you could have silence on your source patch but the VCA gate will still open on a CV signal.
You will only get a signal out of the VCA if the CV is high and there is an actual signal on the input. I call that an AND ...
This is my understanding as well and know I've done this patch before.
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Post by fac » Fri Jun 17, 2016 3:56 pm

VCA = Multiply = AND
Mixer = Sum = OR

I'm talking only about logic signals, of course.

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Post by nuromantix » Sat Jun 18, 2016 1:35 am

Sorry I made a mistake, slip of the mind :)
of course a VCA behaves like an AND, not an OR.

MATHS has OR amongst its many functions!

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Post by mousegarden » Sat Jun 18, 2016 11:49 am

Thanks folks, jeeze !

:ripbanana:

I'm thinking that like some other modules, to get the best out of an OR/logic module, you really have to understand it, some modules you can just mess around with and get results, but not this one I think.

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Post by daverj » Sat Jun 18, 2016 1:17 pm

Here's a couple of graphics I made a few years ago that have probably faded into the distance here on the forum:

Logic gates for AND and OR: (for triggers and gates)
Image


Analog AND and OR (MIN/MAX):
Image

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Post by mousegarden » Sat Jun 18, 2016 1:25 pm

:tu: :tu:

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Post by Dr. Sketch-n-Etch » Sat Jun 18, 2016 2:14 pm

What daverj said.

BTW, the Intellijel uMod II has analog OR and AND functions, and the Intellijel Plog has all six common 2-input digital logic gates available (AND, OR, NAND, NOR, XOR, XNOR). I'll leave it to you to look up the relevant truth tables for the ones daverj didn't mention.

Just as an aside, analog OR and AND are very simple and very useful analog circuit elements. Indeed, four cleverly arranged analog AND circuits provide the basis for the Intellijel Planar, and an analog OR circuit is embedded in the CV control network for the Intellijel uFade.
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Post by orlog24 » Sat Jun 18, 2016 3:50 pm

Thanks for the explanation, I too was a little boggled by it all.

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mousegarden
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Post by mousegarden » Sat Jun 18, 2016 4:48 pm

Dr. Sketch-n-Etch wrote:What daverj said.

BTW, the Intellijel uMod II has analog OR and AND functions, and the Intellijel Plog has all six common 2-input digital logic gates available (AND, OR, NAND, NOR, XOR, XNOR). I'll leave it to you to look up the relevant truth tables for the ones daverj didn't mention.

Just as an aside, analog OR and AND are very simple and very useful analog circuit elements. Indeed, four cleverly arranged analog AND circuits provide the basis for the Intellijel Planar, and an analog OR circuit is embedded in the CV control network for the Intellijel uFade.
Strange that, the Planar is on my shopping list...

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Post by mgscheue » Sat Jun 18, 2016 6:44 pm

I just mentioned in the Ladik Love thread, in the Eurorack forum, that I recently got the Ladik B-010 Bool2. It's a nice little inexpensive module that does digital AND, OR, XOR, NAND, NOR, and XNOR (or NOT, with a jumper setting).

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Post by M6live » Sat Jun 18, 2016 8:05 pm

Redacted.
Last edited by M6live on Sun Nov 26, 2017 11:47 pm, edited 1 time in total.

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Post by mousegarden » Sun Jun 19, 2016 3:20 am

M6live wrote:
Dr. Sketch-n-Etch wrote: BTW, the Intellijel uMod II has analog OR and AND functions, and the Intellijel Plog has all six common 2-input digital logic gates available (AND, OR, NAND, NOR, XOR, XNOR). I'll leave it to you to look up the relevant truth tables for the ones daverj didn't mention.
Hint: Check out the Plog manual. It's helpful and to the point.
Plog sounds cool, I may jump in with that....

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