MUFF WIGGLER Forum Index
 FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 
WIGGLING 'LITE' IN GUEST MODE

CGS89 Wire-OR Gates
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author CGS89 Wire-OR Gates
Revok
https://sdiy.info/wiki/CGS_gate_sequencer

"That is right, this module has been designed so it's outputs can be connected together with its other outputs, or outputs of other CGS89 gate sequencers via wire ORing."

The wire-OR is a really cool function on this one. Can these buffers be added to any gate output assuming the incoming levels are the same or is it more complicated than that?
Graham Hinton
Revok wrote:

The wire-OR is a really cool function on this one. Can these buffers be added to any gate output assuming the incoming levels are the same or is it more complicated than that?


Assuming the levels are the same--don't mix with 5V gates.

The purpose of the 10k outputs resistor is to pull down the output when it is not driven high. The disadvantage is that the more you put in parallel the more current is needed which might not be available. It would be better to have a higher output resistor and a lower input pull down resistor, say 100k and 10k.

Wire-OR is used in instrumentation applications, but it is done the other way around, i.e. low asserted by an open collector transistor or contact to 0V, similar to the Moog S-trig. A 4k7 pullup resistor will be sufficient for most gate signals, but if you want to use higher speed pulses a 220R/330R termination network may be used.
Revok
Thanks for the insight, Graham. I was a bit confused by the current limiting resistors in the schematic but your explanation made it clearer as to why they exist. I'll try some experimenting with the suggested values.

I'll have to dig into the the S-trig style version of this. It sounds like a better solution. I guess the downside would be that gate inputs and outputs would have to be isolated from everything else.
Graham Hinton
Revok wrote:
I'll have to dig into the the S-trig style version of this. It sounds like a better solution. I guess the downside would be that gate inputs and outputs would have to be isolated from everything else.


It's a simpler solution, but not compatible with analogue signals which is why they used a different connector (not a very nice one). The advantage is that sources don't have to be powered, you could just use a switch contact, but that tends to be outweighed by the disadvantage of a different connector.

My thinking is that if you are going to use the same connector for analogue and logic signals then the logic inputs have to be analogue comparators capable of accepting any signal in the system. The advantages of that outweigh the cost of a little extra circuitry and not being able to wire-OR.

How many times do you want to OR? The main application is combining multiple gate outputs from a step sequencer, but that can be done internally with a gate bus. Cheaper too once you factor in the cost of all the cables and mults. Otherwise just make a few OR gates.
Revok
Thanks again, Graham. The comparator on the inputs idea is a good one. I wouldn't have thought of that.

I'm currently building a few CGS sequencers and having recently learned that the wire-OR was even a possibility from the CGS89, I thought to myself, why aren't all of my gates like this? So there's not really a set goal in mind. It seemed odd to me that these weren't used everywhere if it were as simple as the buffer in the schematic so I was skeptical of my understanding of how they worked.

There are probably around 50 or so gate outputs on my current system but it's probably unlikely that I'll need to OR all of them at any point. I imagine even reaching 16 would get difficult without giant banana plug towers. 8 or less is probably a realistic amount that would be used at this time. However, it would be cool to have the ability to stack them all up.
MUFF WIGGLER Forum Index -> Music Tech DIY  
Page 1 of 1
Powered by phpBB © phpBB Group