Good article, pictures too-far-away...

Dear Joe, MRHers,

Good article, with accurate reference info on the various types of switches. I would note however that the example pics of many switches were seperated by a significant distance, in some cases a page or two, from their associated text descriptions. This may make reading<> visual association for some readers a little more difficult than maybe it could be?

I would also ask, where are "microswitches" in the "press button" section?

Overall, a good reference which I'm-sure will be a regular in the Search Box queries going-forward...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Going the extra mile

...and it's Always Appreciated!

Dear Joe,

...and rest assured both your and Patty's efforts are Very Greatly Appreciated by all of your loyal readers...

Many Thanks, and Happy Modelling,
Prof Klyzlr

Updated MRH mag posted

Outstanding article.

I don't know if anyone has taken the approach to figure out how reliable electrical switches are for model railroads, or which ones are the most reliable.  The one omission the wasn't mentioned were momentary spring loaded to off switches.  Some modelers perhaps may still use the old twin coil turnouts, and knowing what momentary spring loaded switches are most reliable  might be useful information. 

On a second reading I think the spring loaded off switch was probably covered in the section on push button switches, but I missed it because he didn't mention the push button switches may either make a connection when pushed and then need to be pushed again to break the connection or it may be spring loaded to make a momentary connection that either breaks when the switch is released or could make a momentary disconnect the returns to close when the button is released.

Good article

I would have liked to have seen some recommendations of what to use and where to obtain switches suitable for model railroading applications. Maybe beyond the source of this article, but suitable for a follow up.

The Care and Feeding of Switches

Thanks for the comments on my article. As to sources for switches, I suggest some online sources of suppliers:

All Electronics:  https://www.allelectronics.com/?gclid=CjwKCAjwzOqKBhAWEiwArQGwaIy0oblmXz-_u_ni7aeW14dW4xBgeoL-ccaWclya82Hpdkzn4lIoPBoCxB4QAvD_BwE

MPJA : MPJA.com

Mouser Electronics : https://www.mouser.com/ProductDetail/Schurter/13019315?qs=tGaZrb6HVSaeSttQbZxh%2FA%3D%3D&mgh=1&gclid=CjwKCAjwzOqKBhAWEiwArQGwaP4uroKCq4EX3fhMwPMislhzOrdb6wFfjgeDhlXQwiY2yQZVLaH7wxoC6_IQAvD_BwE

DigiKey : https://www.digikey.com/?utm_adgroup=DigiKey&utm_source=google&utm_medium=cpc&utm_campaign=EN_Brand_Digi-Key&utm_term=digikey&utm_content=DigiKey&gclid=CjwKCAjwzOqKBhAWEiwArQGwaJx55UTX25FFBEA3loYWL_3E0NtcnzehW6_A6w1bMMLmaizF22mdtxoCEvsQAvD_BwE

Also, Newark Electronics, Radio Shack (online), Sparkfun (https://www.sparkfun.com/categories/145?page=all)

The trick is to find a good quality switch which you can buy in low quantities without having to pay a minimum order. I have had good luck with the first three listed above. 

Manufacturers I like are C&K but there are many more listed here:

https://www.electric-switches.com/toggle-switches/

Make sure the switch ratings are printed or embossed on the side of the switch (if possible). Sometimes the switch may be too small.

Jack

capacitance touch switches

I would very much like to hear the author's take on the touch-screen switches now available for layout control.  I'd love to try them but this article now has me thinking I need much heavier toggle switches for both mechanical and electrical reliability.  As a newbie, I'm afraid of a major investment in time and effort using the wrong equipment or materials and so tend toward a very conservative view with respect to risk.  It seems to me from reading this article that the cost of much better reliability in the switches I purchase is a worthy investment to reduce the risk of future layout problems.  So, are those touch-screen switches prone to less risk of failure compared to traditional wiping metal contacts and solid construction, or are they more likely to fail?

I was wondering

what on/off toggle switch I was going to buy for the staging tracks.  Good timing on Jack's article for me. Good article!  After reading his article, I opted for the,   All Electronics, their advertised SPST ON-OFF HEAVY DUTY TOGGLE SWITCH.  Hole in the facia mount, 15A  screw terminal.    5 for staging tracks, the rest, where ever I might need one......

Capacitive Touch

I know someone who due to skin chemistry or some such unknown conditions cannot make a capacitive touch switch, or screen, operate! For some reason she has low capacitance through her skin. So keep that in mind if you have lots of people over, or you are a club, there might be people that, for no fault of their own, cannot get such a switch to operate!

"touch switches"

Dear ???(dendyal)

"Touch Switches", either Capacitive or Resistive, typically do not do "heavy lift" switching of high-voltages/currents.

Rather, the "Touch Switch" acts as a "input device"
(a method for the Human to tell the Circuitry what the Human wants the Circuitry to do),

and some form of "motherboard" or "base unit" does the actual "heavy lift" switching.
(using Relays, sillicon switches, or similar, which are much closer electro-mechanically to the switches described).

Ergo, the question is not "can a Touch Switch handle the Volts/Current I need to switch?"

but rather

"does the 'host unit' that the Touch Switches plug into have the ability to switch the Volts/Current I need to switch?"
(above pic shows a "Real Switch" base-unit, as offered by Barrett Hill. It features Relay Switching to do the "heavy lifting", but takes it's "Commands" from a plug-in "Touch Switch" unit...   ).

Most "Touch Switch" systems offered for Model RR tasks come as part of proprietary packages,
which neatly takes the "can it handle the task?" question out of the modeller's hands,
and basically says "the manuf has engineered the whole system to work together, just buy the bits, plug together as the instructions say, and enjoy"...

EG Barrett Hills
https://www.berretthillshop.com/store/products/touch-controls/

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Problems with capacitive touch

Dear Brent,

In a previous Professional Role, I was a Factory TechSupport guy for an company that manuf's audio mixing consoles. All of the Faders and Knobs were "touch sensitive", using capacitive-touch. We found that, at least with the first-gen consoles, the knobs/faders could react differently before/after lunch due to the audio engineer having eaten an incredibly greasy hamburger...

Those first-gen touch-controls used an induced sine-wave, referenced to the GND of the console. When the knob/fader was touched, it "flattened" the sine, and the circuitry "knew" it was being touched/manipulated. Dry skin and environment required the Threshold for "touch detection" to be turned-up quite high, which was a manual calibration exercise. Not particularly difficult, but One had to Know how and where to do it...
...and it made it more-painful for "hot console" studios where each session may be handled by a different Operator/Engineer... :-(

One the 2nd-gen consoles, we developed a different technique. The underlying circuitry constantly read the induced sine-wave in the knob/fader, relative to console GND. The Threshold was then set in realtime to half-way between the 2 states. Every time any control was touched, that control "read" the "touch state", and adjusted the "half-way threshold" so it was always a clear "Yay/Nay" state. This worked great, and long-time users of the consoles approved. However, it also masked slow drifts and similar "out of calibration spec" issues with the underlying circuitry, meaning it stayed "working" for longer, but when it "broke", it was definitely broken... (made field-diagnosing easier though....   ).

Anywho, for your friend who "can't make capacitive touch work", look for the "touch calibration" settings in the device (all touch-devices have such "calibration" settings by definition, although they may be hidden in a diagnostic menu), or try to find a "better engineered" device with "realtime auto touch calibration"...

...and re-assure her that she's not alone!

Happy Modelling,
Aim to Improve,
Prof Klyzlr

@prof you may have a suggestion for me.

Hi @prof. 
I don’t want to hijack this thread, but I have a minor issue with the Berrett Hill Touch Toggles. I have them mounted in a cheap photo frame, connected to an Arduino to control servos. The frames have glass (about 3mm) not plastic in them. I find that the toggles can be a little too sensitive, and will sometimes switch unexpectedly, sometimes when I stand too close to the panel - like “bum dialling” a mobile phone.

Do you have any suggestions as to how I might lower the sensitivity of the Touch Toggles? I’ve emailed Kevin a couple of times, but surprisingly have not received a reply. I love the TTs as they elegantly solve the problem of indicating which way the turnouts are thrown.

All of the Faders and Knobs were "touch sensitive"

Hi Prof,   What was the advantage of using touch controls over sliders or knobs? ....DaveB

Pro Audio "touch knobs/faders"

Dear Dave,

Important distinction, these were actual physical knob and faders (not "graphics of knobs and faders on a flat touch-sensitive panel").

The reason for "adding" touch sensitivity to what were physical knobs and faders was that these were digital audio workstation consoles, not just "analog audio mixers". The 1st gen console knobs were motorised, so could both _Input_ rotation values (like PAN, Balance, Gain, etc), but also _replay_ Mix Automation from a multi-track timeline. Touch sense enabled various Automation Write and Read modes, and allowed the system to discern between:

- human moving control, to make changes Inc "Automation in Realtime"

- Automation replay of existing settings changes

Ensuring the Rotation circuitry stayed calibrated so that "knob pointing exactly to 12 o'clock" = "Pan Centre" was one trade-off with this approach. (When you "Blue + Touch" a Pan knob to snap back to "Pan Centre", but the knob moves to 2 o'clock because drift in the circuit means the physical 2 o'clock position IS where the Knob thinks "Pan Centre" is... but the Human looks at their console as thinks "why is that track Panned slightly to the Right?"... it's a unique feeling...)

The later 2nd Gen consoles used "headless" encoder type knobs, so did not "rotate and move" when replaying Automation. (No indicator mark on the physical knob suggesting "2 o'clock = Pan Centre" to keep calibrated   ).

 This also avoided a number of "switching between modes/scenes/tracks VS Physical Knob Position" contradictions which had to be coded-for in the Software <> Human User Interface. (A 12-chanbel console may only have 12 physical knobs + faders "channel strips", but by Bank switching, those 12 control strips can access any of over 1000 tracks... and when you "call" a given track to a Console Channel Strip, all knobs and faders better "jump to" the current values of the audio track you "called for"...)

In both Gen consoles, the Faders were motorised and touch sensitive, so could both Write and Read/Replay Automation moves and other values as needs required. A fave trick for trade shows was to flip between banks, making every motorised control "jump" between different values, or program an automation timeline with "moving snake" sequence of fader/volume moves...

(Cue "Vegas Mode"...  

He who dies with the most knob/faders/controls moving and lit-up on the console wins...   )

It's the knowledge of these "Tactile User Interface" controls, for missions far more critical than "the typical model railroad", that inform my personal choices Re 

- pots over encoders

- tactile hardware knobs over raw "touch screens"

- dedicated control input devices for defined tasks over "generalised User Interfaces"

- "1st Order Accessibility" over "SHIFT Key" or "Swipe to access..." user interfaces.

I hope thus helps...

Happy Modelling, 

Aim to Improve, 

Prof Klyzlr

PS Google "Fairlight Dream II Constellation console" (1st Gen) and "Fairlight POST EVO console" (Gen 2)

I've been exploring

I've been exploring capacitive touch control with Arduinos... there should be lines in the sketch that refer to the sensitivity of the sensor. By adjusting those threshold numbers, you can fine tune the sensors to the point you actually have to make contact with them (or the glass over them...) If you output the values the sensors are reading to serial print , you can see exactly what the value is at any given moment, and adjust them in the sketch accordingly.

One of the entries in my blog (Touch control panels for pennies - Literally... see link below!) has a short sketch that dumps the output of the sensor to serial print for monitoring. That should help you figure out what you should be setting up the sensors to respond to.