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Pots in schematics

Started by muddyfox, July 18, 2014, 06:35:53 PM

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muddyfox

OK I'm just too dense for certain things... can someone handhold me through this one, please?
Here's a schematic. There are five pots in there and for the life of me I can't figure out which way should pins 1 face and why?
Thanks!



jtn191

#1
Had a quick look at this vero layout...
Spacing (1= top?)
Smoothness (1= bottom)
Depth (1= top)

If you get 1&3 swapped, the worst that can happen is your pot works backwards: turning it left will speed the trem up etc

alanp

I get tripped up on this quite badly as well! (The Resonance on my Steiner Parker VCF is backwards. I think.)

I try and figure out which end of the rotation is supposed to be what, and work that back to the pot's rotation. And get it wrong sometimes, too :(
"A man is not dead while his name is still spoken."
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madbean

It's pure laziness not to give some indication on schematics. I don't know why people do that.

The only way to know for sure is by analyzing the circuit and figuring out is the pot is supposed to increase or decrease resistance when it is turned clockwise. If it is increasing resistance, the two connections must go to lugs 1 and 2 of the pot. If it decreasing, then it is lugs 2 and 3 (lug 2 is the wiper in both cases). Sometimes the wiper and the remaining outside lug will be tied together, sometimes not. For example, in the case of decreasing resistance, you could have lug1 and 2 tied together. It is the same result as leaving lug1 un-tied.

Here is an easy way to connect a visual to the action: lugs 1 and 2 EXPAND resistance, lugs 2 and 3 CONTRACT resistance.

In the example shown, I can tell right away that in the trimpot on the upper schematic that lugs 2 and 3 are tied together to EXPAND resistance. This is because increasing resistance in that spot will increase output of the circuit. Conversely, on the Depth knob on the schem below, I can tell that lug 3 is tied to the 330R resistor and the wiper connects to that 1k in parallel with the LED. That's because the depth of tremolo will increase as the LED gets brighter, and the LED gets brighter when there is less resistance going to it. For the Speed and Fine pots, the rate of the LFO increases as the resistance decreases. So, those are lugs 3 and 2 that are connected.  And, so on.

muddyfox


Thanks B.!
Makes perfect sense, it's just gonna take a few dozen read-throughs to internalize it.  ;)