#1
I have notice that it was also common to use inverter (NOT gates) for analog electronic projects, such as distortion box.

While I understand tube/transistor operations in analog circuits, and understad gates in digital circuits, I am uncertain as to how the gates are used in analog projects. do they flip the signal (making it out of phase) or something, or does it do something else?

Particularly, i am wondering how the 4049 are used http://www.generalguitargadgets.com/diagrams/catrssc.gif and the Double D circuit in runoffgroove.

Also, aside from NOT gates, are there any other logic chips that can be used for analog purpose?

Lastly, if it is a phase invertion, how would it sounds when compare to use a good FET?
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Last edited by Jestersage at Jun 14, 2008,
#2
Thats an interesting subject, id guess that with a NOT gate, you'd get output signal, up until the threshold at which the input signal would be deemed "high". At which point it would cut off. Now that would be a weird and kind'uve useless effect to use!!

Although, thinking about it, "high" is normally about 9 volts, yet a guitar signal, even when heavily boosted, is only ever gonna be 2 volts absolute maximum. Perhaps the NOT gate is a over-volting protection device?

Also, the logic gates might not actually be in the signal path, and might be being used digitally, but to control the analog signal. Like in my homemade vibrato: one half of an ecc83 valve is used to self oscillate, and that signal in turn varies the gain of the other ecc83 stage, causing a oscillating gain. This of course give you your classic vibrato. if the oscillator is digital, it is possible it may use logic gates to control it.
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Last edited by blub man at Jun 14, 2008,
#3
Interesting indeed, but get that rick roll out of your sig or I'll report you. That was fucking annoying.
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#4
Hahaha, so it got someone, well it does say don't click... Consider it gone...
MIM Tele
Yamaha Pacifica 112
Marshall ED-1 Compressor
Morley Power Wah
Boutique booster
Digitech Bad Monkey
Electro Harmonix Small Clone
Electro Harmonix #1 echo
THE BEAST (head)
Line 6 Spider II head
D130F
Greenbacks
#5
Okay, read up a bit on electronic gate more. Basically, electronic gate is still "analog", in the sense that it will output something based on the voltage it output. Since voltage will always be varied, even in solid state, they set it so that, for a certain range of voltage, it becomes 1, and for another voltage, it becomes 0. Guess that's how they built the computers with tubes.

The question then is... how does the NOT gate do "out of phase"? I want to create a stereo lesile or stereo tremolo.
Ibanez SA-120 (ed.2006)
BluesJr 1996-B + cathode follower + texas Heat
Crate CPB150
Homemade 4 x 10 cab Bass closeback
Metal Muff
Last edited by Jestersage at Jun 14, 2008,
#6
Inverting buffers are basically just inverting comparators, not amplifiers. Amplifiers are meant to copy and amplify a signal, regardless of voltage, within its limits. A comparator's output switches quickly from high to low, or low to high, depending on the input voltage. The input voltage is compared to a set threshold. With an inverter, if the threshold is exceeded, the device sinks the output, implementing a low. If the input is below the threshold, the output sources, or is high. The analog aspect of the circuitry is retained because it takes time for the output to switch, usually tens of nanoseconds.

What do you mean, "out of phase"? That circuit you posted should work for what you want to do, I would think. The buffers are only used to create an oscillator, and won't affect the "tone" of your signal, just the amplitude.