Stuff you wanted to know but were afraid to ask

I was just thinking about something I always wondered but never was able to find out and remembered this thread. I wanted to use a CA3130EZ in a rat style circuit, do I need to protect the input like one does with a standalone mosfet? Do I just use the standard Zener to ground at the input? Also wondered If I have a mosfet after different amplifier in the middle of a circuit, do I need the Zener there too?
 
mhshizz said:
I truly appreciate all your efforts. Chuck's post seems to be above my technically, while Mr Black's article features a painfully juvenile writing style and analogies I can't quite parse.

It seems this is a "me" problem, so I'll just go back to telling myself to not worry about and trust that people I respect behind the projects I like know what they're doing.
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I'm with you, stuck between technical jargon above my pay grade and confusing metaphors.

A Fuzz Face cleans up because it has low impedance and therefore it loads the pickups?
Whereas a Tone Bender Mk2 has a buffer, i.e. the 1st transistor stage, so it doesn't clean up?

Or maybe I should just keep building by numbers and play my guitars...
 
I think any gain pedal “cleans up” if you turn the volume down, in the sense that the sound gets cleaner because the overall gain is being reduced. The thing with the fuzz face is that when you do that, you are dramatically changing the relation between your pickup’s output impedance and the pedal’s input impedance, which ends up really affecting the sound in ways that people love. It’s a bit of a happy accident: the impedance mismatch is notoriously a “bug” not a feature (it goes against any EE 101 design practice) but it seems to work well in this case. Buffered pedals (or really any pedal with a high input impedance) don’t do that because even if you roll the guitar volume down, the pedal will not “load” the pickup; the pedal’s input impedance is still high enough to handle the changing impedance due to the volume roll off on the guitar side.
It’s hard to understand this stuff without knowing the math because I don’t think there are really good equivalents in the mechanical world or in any other every day experience that could help with understanding. I could come up with some metaphors but they will most likely all fall short.
 
spi said:
High impedance input: peeing into a toilet, you're going to make the water yellow.
Low impedance input: peeing off a cliff, you're not going to make the water yellow.
Yellow is your highs.

That metaphor sounded better before I wrote it down.
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No I get it now. The ocean is low impedance so you need a lot of pee to make it yellow.
The ocean loads your peen much more than a toilet. Eventually you fall off the cliff and you shatter on the shore. Then the garbage collectors pick up your pieces aka "cleanup."
 
I often think about it in terms of water pressure. If your pipe gets wider, you will lose pressure. That’s what a pedal with low input impedance does: it’s a wider pipe than what you have before and thus your guitar signal loses high end (pressure in this analogy). On the other hand, a pedal with high input impedance is analog to a very narrow pipe so even if the one before is already pretty narrow, you won’t lose pressure. If we want to make the metaphor a bit more accurate, when it comes to electrical signal we have different pipes for different frequencies, and high end pipes are affected more than low end ones… am I making any sense?
 
Am I crazy or was there a Product Requests subforum that has recently disappeared? Reading through the thread containing sort of an origin story of what became the Hen's Tooth was fascinating. Or am I gaslighting or Mandela effecting myself?
 
I had one (a question) but forgot it, so here's another one I came up with...

Most PullDownResistors are 1M or 2M2, but I've got a shipload of 6M2 — is this too high of a PDR value, how will it affect the rest of the circuit?

I read somewhere once that a PDR could be anywhere from 1M to 10M, but I can't find that reference again and whoever said it may have been full of bunk.

Sorry, I've been too lazy to do the math on input impedance etc...

Can I use my 6M2 stash for PDRs?
 
Feral Feline said:
I had one (a question) but forgot it, so here's another one I came up with...

Most PullDownResistors are 1M or 2M2, but I've got a shipload of 6M2 — is this too high of a PDR value, how will it affect the rest of the circuit?

I read somewhere once that a PDR could be anywhere from 1M to 10M, but I can't find that reference again and whoever said it may have been full of bunk.

Sorry, I've been too lazy to do the math on input impedance etc...

Can I use my 6M2 stash for PDRs?
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I dunno, but I’m breadboarding later…I’ll try it (though I’m sure someone will let you know anyway).
 
Feral Feline said:
I had one (a question) but forgot it, so here's another one I came up with...

Most PullDownResistors are 1M or 2M2, but I've got a shipload of 6M2 — is this too high of a PDR value, how will it affect the rest of the circuit?

I read somewhere once that a PDR could be anywhere from 1M to 10M, but I can't find that reference again and whoever said it may have been full of bunk.

Sorry, I've been too lazy to do the math on input impedance etc...

Can I use my 6M2 stash for PDRs?
Click to expand...
Here was my rudimentary finding; yes Virginia, you can use a 6m2Ω PDR…at least on a Burnin’ Rubber pedal (my personal breadboard of the Raincoat). I’ll just leave the 6m2 in there.
 
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