JonDent - Exploring Electronic Music: LZX Castle video Synth

Sunday 11 November 2018

LZX Castle video Synth - 101 quad gate

Some build pics of the LZX quad gate module.
This is in Eurorack format.
The LZX official site describes it thus:
"The Quad Gate uses a single quad logic chip and combines them in 4 different ways."
(A single CMOS input/output is called a Logic Gate.)

The Quad gate is similar to the multi gate in that it uses logic gates for binary combination, but it uses a single gate type (ex. Xor. Depends on what you build it with. I (Philip) suggest xor). There are 2 sets of 2 inputs. A1, b1 and a2, b2. These have they're own outputs, out1, out2. But there are 2 other outputs that are some combination of inputs and outputs to make further interesting combinations.

The important component is a CMOS logic gate.
I'm using a CD4070BE in this build but alternatives are the CD4011 and CD 4001

The CD4070 is a quad XOR gate.
It has four Exclusive OR gates. It has two inputs per gate.
A true output results if one, and only one, of the inputs to the gate is true. If both inputs are false (0/LOW) or both are true (1/HIGH), a false output results.
A way to remember XOR is "one or the other but not both".

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Alternatives:
The 4001 - NOR gate (NOT - OR)
It's an inverting OR gate.

A true output (1/HIGH) results if both inputs are false (0/LOW).
If either or both inputs are true (1/HIGH), a false output results.
(this is the reverse of the NAND gate)

Notice the small circle at the output on the schematic symbol. This means that the gate is inverting.
Remember that a NOT gate is an inverter.
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Alternative:
The CD 4011 - NAND gate (NOT - AND)
It's an inverting AND gate.
This produces a false output (0/LOW) only if all its inputs are true (1/HIGH)
If either or both inputs are true (1/HIGH), a true (1/HIGH) output results.
(This is the reverse of the NOR gate)

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So it may be interesting to build these 2 alternatives.
Back to the build.