Ever look in a stereo receiver or something similar, and there is a selector switch. Maybe it is the switch that selects phono, tape, aux, tc.
Inside behind the knob there is a shaft sticking back through the switch assembly. There will be a more or less disc shaped flat thing with the moving contacts. Often times there is more than one of these flat disc things, spaced along the knob shaft. A couple long screws down two sides holds this whole thing together.
Each of those flat disc things with moving contacts is a deck.
You might want 4 poles with three positions each. You could fit all that on one deck. But maybe for channel separation you might want some space betwen them, so you might put 2 poles and their switched positions on one deck and the other two on a second deck. For that matter, maybe you are switching bands on a short wave radio and you need each switch section spatially separate from the others, so you could specify four decks.
Here is a three decker:
Inside behind the knob there is a shaft sticking back through the switch assembly. There will be a more or less disc shaped flat thing with the moving contacts. Often times there is more than one of these flat disc things, spaced along the knob shaft. A couple long screws down two sides holds this whole thing together.
Each of those flat disc things with moving contacts is a deck.
You might want 4 poles with three positions each. You could fit all that on one deck. But maybe for channel separation you might want some space betwen them, so you might put 2 poles and their switched positions on one deck and the other two on a second deck. For that matter, maybe you are switching bands on a short wave radio and you need each switch section spatially separate from the others, so you could specify four decks.
Here is a three decker:
An externally hosted image should be here but it was not working when we last tested it.
So having two decks (DPDT) is like having two DPDT switches controlled by a single shaft? My assumption was that the decks are not electrically connected in any way so they are independent. Is that right, or are all the decks electrically connected?
There are 2 incoming sources, but these 2 sources must not come into contact with each other at the rotary switch.
I want to use 4 different values of capacitance for the left and right channels. Instead of having to desolder and solder a cap everytime I want to change the capacitance for the right and left channels, I thought of using a rotary switch for it.
That said, what type of rotary switch is it? Or what would you recommend for this type of situation?
There are 2 incoming sources, but these 2 sources must not come into contact with each other at the rotary switch.
I want to use 4 different values of capacitance for the left and right channels. Instead of having to desolder and solder a cap everytime I want to change the capacitance for the right and left channels, I thought of using a rotary switch for it.
That said, what type of rotary switch is it? Or what would you recommend for this type of situation?
The decks are electrically independent, with no connections between.
If you are making a selector, for example you could space two decks apart enough that each cap was wired from the same position on each deck, then the common from each deck becomes the two ends of the selected cap, if you follow me.
These open frame switches are very old school. Nothing wrong with them, but old school. There are newer little rotary switches that look more like pots, and they can be had ganged.
Look inside some old Pioneer or Sansui or something with rotary selector switches on the panel and see how they are used.
If you are making a selector, for example you could space two decks apart enough that each cap was wired from the same position on each deck, then the common from each deck becomes the two ends of the selected cap, if you follow me.
These open frame switches are very old school. Nothing wrong with them, but old school. There are newer little rotary switches that look more like pots, and they can be had ganged.
Look inside some old Pioneer or Sansui or something with rotary selector switches on the panel and see how they are used.
I see now. So a 2 deck with one pole each is what I would be looking for right? Makes sense since there's only one input and one output per channel. I'm currently looking at the Grayhill 71 series.
The only thing that worries me is the switch. It's when there is a momentary break in contact when changing positions. Not to mention the possibility of it being left in between 2 positions! This is equivalent to pulling the caps out and inserting another one in while the amp is on. In the original design there is never a break there. I don't know, maybe I'm over-thinking it.
The only thing that worries me is the switch. It's when there is a momentary break in contact when changing positions. Not to mention the possibility of it being left in between 2 positions! This is equivalent to pulling the caps out and inserting another one in while the amp is on. In the original design there is never a break there. I don't know, maybe I'm over-thinking it.
OK, valid points.
The switch positions have detents. Mechanical stops. Just like the selector switches you find on some old Pioneer receiver. You probably COULD manage to stick a switch halfway between positions, but you would have to be trying to do it. Think about all the switches you encounter day after day, toggles, rockers, rotary, any others, how many of them can you set halfway between states? And without making a large effort to do so, how many times have you moved a switch only to find it stopped between positions? I don;t think that is a major concern here.
In switches, there are two ways to move a contact. One is to make contact with the next position before breaking contact with the last - "make before break" - and the more common break contact with the old position before making contact with the new position - "break before make." The term for make before break is a "shorting" switch. The term for the break before make switch is a "non-shorting" switch
If you are concerned with a momentary open circuit between selections, then a shorting switch would be your choice. Of course that would mean the two adjacent caps would be briefly in parallel before the switch setttled on the new selection, but if that is preferable to a brief open, then that is a choice.
Look at available switch deck options and see if they offer both shorting and non-shorting contacts.
Here is another option. I will make up an example. Say you wanted to select from .01uf, .02uf, .04uf, and 1uf. You could get each of those caps and switch between them. You would then have to either have the brief open circuit of a non-shorting switch, or the brief over-value when the two positons were in parallel with a shorting switch. Alternatively, since caps add in parallel, you wire the .01uf in permanently, then for the .02uf, instead of a .02uf cap, you just switch in a second .01uf cap in parallel, then add yet another additional .02uf cap to make .04uf, and finally add in a .06uf to make a total of 1.0uf. Basically you add three new on switches. That way there is never an open, and ther is never that unwanted combination.
There are switch decks that connect the common progressively to each pole without disconnecting the ones already selected. If you follow me.
We do this in guitar amps when we want to change cathode bypass caps for tonal reasons. Instead of selecting betwen a 0.68uf and a 22uf cap, we just wire the 0.68uf cap permanently and switch the 22uf in and out in parallel.
The switch positions have detents. Mechanical stops. Just like the selector switches you find on some old Pioneer receiver. You probably COULD manage to stick a switch halfway between positions, but you would have to be trying to do it. Think about all the switches you encounter day after day, toggles, rockers, rotary, any others, how many of them can you set halfway between states? And without making a large effort to do so, how many times have you moved a switch only to find it stopped between positions? I don;t think that is a major concern here.
In switches, there are two ways to move a contact. One is to make contact with the next position before breaking contact with the last - "make before break" - and the more common break contact with the old position before making contact with the new position - "break before make." The term for make before break is a "shorting" switch. The term for the break before make switch is a "non-shorting" switch
If you are concerned with a momentary open circuit between selections, then a shorting switch would be your choice. Of course that would mean the two adjacent caps would be briefly in parallel before the switch setttled on the new selection, but if that is preferable to a brief open, then that is a choice.
Look at available switch deck options and see if they offer both shorting and non-shorting contacts.
Here is another option. I will make up an example. Say you wanted to select from .01uf, .02uf, .04uf, and 1uf. You could get each of those caps and switch between them. You would then have to either have the brief open circuit of a non-shorting switch, or the brief over-value when the two positons were in parallel with a shorting switch. Alternatively, since caps add in parallel, you wire the .01uf in permanently, then for the .02uf, instead of a .02uf cap, you just switch in a second .01uf cap in parallel, then add yet another additional .02uf cap to make .04uf, and finally add in a .06uf to make a total of 1.0uf. Basically you add three new on switches. That way there is never an open, and ther is never that unwanted combination.
There are switch decks that connect the common progressively to each pole without disconnecting the ones already selected. If you follow me.
We do this in guitar amps when we want to change cathode bypass caps for tonal reasons. Instead of selecting betwen a 0.68uf and a 22uf cap, we just wire the 0.68uf cap permanently and switch the 22uf in and out in parallel.
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