knob tact switch like MXR

[POTL]

MXR uses tact switches for various functions, such as switching a buffer, changing the operation of a phaser, setting flanger presets, etc.
Such switches usually have 1, maximum 2 groups of DPDT / SPST contacts, but MXR in addition uses LEDs, sometimes functions where more contact groups are needed. What are the different switch methods (CMOS / Transistors) that can be controlled with tact switches?

[Ben N]

I'm not sure what a tact switch is, but I can think of a few politicians who could use one. 

[duck_arse]

a tactile switch is just a push button switch with an added flick/click/flinger thing, that adds something like hysteresis to the throwing action of the actuator. it says nothing at all about the switching contacts. you only need a single pole single throw pushbutton, probably, which once interfaced w/ a debouncer of some description will operate any electronic switching system you can think of. more or less. what you hang off the end of that switching system is only limited by your imagination, not by the switching action.

[Ben N]

Ahhh, tactile.

[Ice-9]

As it has been said above they are not tactile switches, I think the thing you may be looking for are this type of small push button switch , I have seen these in many MXR pedals. I have an MXR VH phaser which has a small switch at the top of the pedal and if that is the type you want then yes these are them.

https://uk.rs-online.com/web/p/tactile-switches/7561363/

[duck_arse]

As it has been said above they are not tactile switches, I think the thing you may be looking for are this type of small push button switch , I have seen these in many MXR pedals. I have an MXR VH phaser which has a small switch at the top of the pedal and if that is the type you want then yes these are them.

https://uk.rs-online.com/web/p/tactile-switches/7561363/

Yellow Lever Tactile Switch, Double Pole Double Throw (DPDT) 200 mA @ 14 V dc Through Hole

so tactile or not? and from lower down the RS page ....

The ESB33 type (stock number 756-1363) is a non-shorting DPDT Push Switch with a latching (self-lock) action. It has a 2.3mm full travel, 3N operating force, 13.5mm overall body height and straight terminals that are suitable for wave soldering.

non-shorting? what does that mean?

[EBK]

non-shorting? what does that mean?

Same as break-before-make, I believe.

[Ice-9]

Yellow Lever Tactile Switch, Double Pole Double Throw (DPDT) 200 mA @ 14 V dc Through Hole

so tactile or not? and from lower down the RS page ....


[/quote]

Good point, I use the latching dpdt ones rightly or wrongly I call the momentary push button ones as tactile, the latching dpdt I don't.

[POTL]

Hi again
I studied the subject matter of my question a bit and found options that interested me.
The idea is to use a microcontroller and clock buttons without locking.

I have the following questions, which is better to use for switching? CD4066 or jfet / mosfet transistors.
Which components less affect the sound, its capacity and resistance?
If you use transistors, which is preferable? jfet or mosfet? which models? j113 2n7000 or others?

The control will be done by a digital device, does it make sense to worry about the effect of the number on the sound (interference as an example), if so, how best to avoid problems?

[vigilante397]

I just read through the datasheet of the CD4066, having never used one before, and I wasn't super impressed. It says typical on-state resistance is 125ohms, which is TERRIBLE. If you're switching LEDs or things like that it doesn't really matter, but for switching audio you're effectively putting a resistor in series with your signal. MOSFETs typically have a lower resistance, which you can find in the datasheet usually labeled as rDS(on), or the resistance between drain and source when the device is on. I use 2N7000 a lot for switching simple stuff, and it has an rDS(on) of 5 ohms. J113 isn't much better than the CD4066 with an rDS(on) of 100 ohms.

So if you're switching audio, of the options you listed, I vote for 2N7000

[POTL]

I just read through the datasheet of the CD4066, having never used one before, and I wasn't super impressed. It says typical on-state resistance is 125ohms, which is TERRIBLE. If you're switching LEDs or things like that it doesn't really matter, but for switching audio you're effectively putting a resistor in series with your signal. MOSFETs typically have a lower resistance, which you can find in the datasheet usually labeled as rDS(on), or the resistance between drain and source when the device is on. I use 2N7000 a lot for switching simple stuff, and it has an rDS(on) of 5 ohms. J113 isn't much better than the CD4066 with an rDS(on) of 100 ohms.

So if you're switching audio, of the options you listed, I vote for 2N7000

thanks for the answer
I'm interested in switching directly to the audio part of the devices.
I do not plan to use them for bypass, I am interested in using buttons to replace toggle switches, I plan to change capacitors and resistors.
As a primitive example, fat mod in scrimer or mid scoop / flat / boost in big muff.

[Ripthorn]

There are rotary encoders with built in switches that can be interfaced with microcontrollers pretty easily. If you are wanting to change things like caps or other components, the microcontroller could control relays which will do the actual path switching, so no digital audio path. Do you have a specific example of what you want to do in a specific circuit. This would help us find what the best solution to your problem might be.

[vigilante397]

There are rotary encoders with built in switches that can be interfaced with microcontrollers pretty easily. If you are wanting to change things like caps or other components, the microcontroller could control relays which will do the actual path switching, so no digital audio path. Do you have a specific example of what you want to do in a specific circuit. This would help us find what the best solution to your problem might be.

Relays are the best for switching audio as they have a series resistance of nearly zero, but to clarify using a FET or CD4066 as a switch is very different from a digital audio path. If you have the space and can supply the current required for relays, that's your best bet. Otherwise MOSFETs are a pretty good second place.

[POTL]

There are rotary encoders with built in switches that can be interfaced with microcontrollers pretty easily. If you are wanting to change things like caps or other components, the microcontroller could control relays which will do the actual path switching, so no digital audio path. Do you have a specific example of what you want to do in a specific circuit. This would help us find what the best solution to your problem might be.

I have no specific ideas, I'm just curious to use buttons instead of toggle switches.
There can be many variations of use.
1) Simple things where spst is required, in the spirit of disabling clipping or fat mod on overdrive pedals.
2) Switching capacities in the spirit of the mesa boogie mark series when capacitances in the cathodes or in the tone stack change.
3) Переключение емкости в конденсаторах в clock в модуляции.


I am interested in what it can painlessly replace conventional toggle switches, without creating problems with resistance and capacitance, without creating interference and without spoiling the sound.
Or are classic switches the easiest and most practical solution nowadays?

Why am I interested in buttons? The reason is simple, the place, with one button you can switch several components, but it will take up less space than the toggle switch for 3 or 4 groups of contacts.
Buttons can be installed under two rows of buttons and the chance to touch them with your foot is less than a protruding toggle switch.

[ElectricDruid]

I just read through the datasheet of the CD4066, having never used one before, and I wasn't super impressed. It says typical on-state resistance is 125ohms, which is TERRIBLE. If you're switching LEDs or things like that it doesn't really matter, but for switching audio you're effectively putting a resistor in series with your signal.

It's true that the CD4066 isn't a fantastic chip, but it's definitely *old* tech at this point, and there are many better options available with much lower on resistances. That said, they were widely used in the audio path of many famous vintage synths, and no-one complains about those, so they're not all bad.

Anyway, what's the problem with 125R of series resistance? It's not like we don't ever put resistors in series with our signal. Every RC lowpass filter does exactly that. Every inverting op-amp does exactly that. I generally put a 560R in series with the output of all my pedals, and many other designs do something similar, to avoid the output getting fried if someone shorts it to ground, and to help the output cope with capacitive loads. If you want to switch signals on and off going into a mixer, use a 4066. The input resistors for the mixer can be 10K, and the extra resistance of the switch is only 1.25% (e.g. only a fraction over the variation between the resistors themselves, assuming you used 1% resistors). There's no way you'll hear that.

That's not to say 4066's aren't without their problems. The biasing requirements can be a pain, and worse still the resistance can vary with signal level, which introduces some distortion. So they're perhaps not "ultimate hi-fi", but they're not bad for the 1980's, or the price.

For the OP's purposes of switching components inside a circuit...it'd depend on the exact situation, as it so often does. Some places it might be pretty easy to arrange, whereas others will be harder. That's also true for FETs. Relays are conceptually simple from that point of view, since you're just banging two bits of metal together. But for me personally that's the downside - you're just banging two bits of metal together! It all feels a bit 19th century, even if we control the relay with encoders and a microprocessor. Other people feel differently and that's fine, but for me I like purely electronic solutions where possible.

I suspect for the required uses, relays are the way to go. You can use one button to control as many relays as you need, so you can have a "7PDT" or an "SP9T" switch or some crazy thing if that's what you want. And since it's just joining up metal and metal, you shouldn't have any trouble with extra resistance or capacitance. The only trouble will be power and space to run all this stuff, and possibly clunking noises when it all switches.

Tom

[POTL]

I just read through the datasheet of the CD4066, having never used one before, and I wasn't super impressed. It says typical on-state resistance is 125ohms, which is TERRIBLE. If you're switching LEDs or things like that it doesn't really matter, but for switching audio you're effectively putting a resistor in series with your signal.

It's true that the CD4066 isn't a fantastic chip, but it's definitely *old* tech at this point, and there are many better options available with much lower on resistances. That said, they were widely used in the audio path of many famous vintage synths, and no-one complains about those, so they're not all bad.

Thanks for the detailed answer.
I wrote about cd4066 because only I saw it in simple effects (EHX Big Muff with tone wicker).
I do not chase old technologies and taking into account all the nuances, I will drop the idea with cd4066.
We still have a fet, judging by datasheets mosfets look preferable to jfets, maybe I'm missing obvious things and are there still more relevant ways to switch?
As for the relay, yes this is the most obvious option and you are right, they take up too much space, this completely makes the idea meaningless.
Anyway, what's the problem with 125R of series resistance? It's not like we don't ever put resistors in series with our signal. Every RC lowpass filter does exactly that. Every inverting op-amp does exactly that. I generally put a 560R in series with the output of all my pedals, and many other designs do something similar, to avoid the output getting fried if someone shorts it to ground, and to help the output cope with capacitive loads. If you want to switch signals on and off going into a mixer, use a 4066. The input resistors for the mixer can be 10K, and the extra resistance of the switch is only 1.25% (e.g. only a fraction over the variation between the resistors themselves, assuming you used 1% resistors). There's no way you'll hear that.

That's not to say 4066's aren't without their problems. The biasing requirements can be a pain, and worse still the resistance can vary with signal level, which introduces some distortion. So they're perhaps not "ultimate hi-fi", but they're not bad for the 1980's, or the price.

For the OP's purposes of switching components inside a circuit...it'd depend on the exact situation, as it so often does. Some places it might be pretty easy to arrange, whereas others will be harder. That's also true for FETs. Relays are conceptually simple from that point of view, since you're just banging two bits of metal together. But for me personally that's the downside - you're just banging two bits of metal together! It all feels a bit 19th century, even if we control the relay with encoders and a microprocessor. Other people feel differently and that's fine, but for me I like purely electronic solutions where possible.

I suspect for the required uses, relays are the way to go. You can use one button to control as many relays as you need, so you can have a "7PDT" or an "SP9T" switch or some crazy thing if that's what you want. And since it's just joining up metal and metal, you shouldn't have any trouble with extra resistance or capacitance. The only trouble will be power and space to run all this stuff, and possibly clunking noises when it all switches.

Tom

[PRR]

I just read through the datasheet of the CD4066,..., and I wasn't super impressed. It says typical on-state resistance is 125ohms, which is TERRIBLE.

You kids today! Get off my CMOS!  (yes boomer)

4066 was used in many still-respected mixing consoles. With excellent overall specs. Yes, you do have to know the tricks and pitfalls. Yes, today it may not be worth any hard thinking. Unless you will make a million units and need to shave part-pennies.

[POTL]

A relay would be ideal if not for size.
My idea is to replace the switches with clock buttons in order to gain a place inside and increase safety, the buttons that protrude slightly out of the case are more difficult to break with a foot than switches.
Transistors are smaller, although there may be very compact relays, but I think they will be noticeably more expensive than transistors.
I looked at datasheets on jfet and mosfet, mosfet resistance is lower, however, I don't understand which capacitance parameter to look for me =)