Panel Controls

[Bo Deadly]

I'm looking at panel controls and trying to figure out what to use based on availability and what will work in my vertical mount system. This has always been a huge problem for me. I'm building one-off projects just for kicks. I don't sell boards or anything like that. This is strictly a hobby.

I have modeled various common panel controls in Sketchup. From left to right you have an SMD momentary button, 2mm LED, Alps 9mm, sub-mini toggles, Alpha 9mm vertical, Alpha R17 rotary switch, Lorlin rotary, Grayhill 71BD30 rotary, Bourns 51AAA and at the end is a Bantam TT jack. This is not an actual unit, it's just supposed to show the relative positions of bushings and such. These are accurate models created from datasheets and from measurements made with a micrometer:

The translucent grey is the 3 mm aluminum panel and the green is PCB.

So the general idea is that the Alpha 9mm vertical pot would be used wherever possible. This defines a 10mm gap between the panel and the first PCB (each module is a stack of PCBs connected with standoffs extending back from the panel). The toggles fit well, I can use right angle 9mm w/ adapters and I could make holes for somethings if necessary. Most modules have LEDs (at least 1, probably 2, some have 10) and momentary buttons that need to be mounted close to the panel so really big controls like the Lorlin switches are not going to work.

So, my first question is, in general, does anyone have recommendations for improving this scheme? I have been flip flopping between the above scheme OR mounting the controls on the PCBs and not the panel like this:

But I am concerned about structural integrity. And unfortunately it looks like 15mm long shafts are starting to dominate and they just don't reach through the 1.2mm PCB + ~3.9mm gap + 2.5mm panel and still grab the set screw of even the smallest knob.

Another question is, what do you think of the Alpha SR1712F rotary switch? It is highly available and comes in 2 pole 4 pos and 1 pole 8 pos. It could be used a LOT in a vertical mount system like this. It's rated 16V DC 0.3A so I think it should be able to handle 32V AC 0.15A no problem right?

Can anyone recommend parts that I should look at? I have a lot of momentary buttons and LEDs so if I use the 10mm space, I need to find a different momentary button (maybe with builtin LED).

 

[abbey road d enfer]

As a result of all the constraints you expose, many manufacturers have opted for a right-angle position of the PCB (resulting in controls not being in a straight line). Others, who have the possibility to order custom parts, use custom-length shafts and custom knobs. Unfortunately, DIYers do not have these possibilities, which restrict the choice. Most of the times, you'll need to have several daughter boards bearing the rotary switches or some large push-buttons.

 

[ruffrecords]

I have struggled with this same problem for years in trying to design tube mixer modules. I do not think there is a single easy solution.  Because my modules are Eurocard plug in types, there is a main PCB at right angles to the front panel. On this you can mount right angle controls, like the Grayhill switches and ALPS push buttons and simply adjust their position on the PCB so they protrude correctly through the front panel. However, you can have only one vertical line of them and the line is ragged because each right angled control often has its shaft at a different height above the PCB. So, for flexibility I later mounted other controls directly on the front and hand wired them to the PCB. This give total front panel flexibility but is a nightmare to wire up.

My current scheme uses a combination. I still have Grayhill switches mounton the Eurocard PCB. I then have a separate PCB for pots and switches that works much like your scheme and I have standardised on Alpha 9mm vertical pots and sub-min toggle switches, both of which are almost identical in height. I use the pots to fix the PCB to the front panel and let the toggles just protude. The problem with this is finding suitable compatible rotary switches. However, Holger Classen recently showed me a very handy miniature switch, the NKK MRK series, which just so happens also be be almost exactly the same height as the alpha verical pots and the sub min toggles. It comes in 1P12W and 2P6W types

http://uk.farnell.com/nkk-switches/mra112-a/rotary-switch-sealed-long-shaft/dp/1524323

The only problem is it has a 2.3mm diameter shaft - there is a version that comes with a black knob.

I have not looked at the alps SR1712F but  they look to be mechanically compatible with the 9mm vertical pots so that alone makes them worth investigating. Are they readily avilable?

Cheers

Ian

 

[JohnRoberts]

No easy answers. At Peavey I had access to series of pots and switches standardized for similar vertical or horizontal mounting height, a luxury you can afford when tooling up semi custom parts and buying thousands at a pop.

For one-off DIY you need to do exactly what you are doing.  Good luck.

JR

 

[Bo Deadly]

... the NKK MRK series, which just so happens also be be almost exactly the same height as the alpha verical pots and the sub min toggles.

Indeed. I actually have some of these switches (the Alco ones are basically identical). I always discounted them because of the 1/8" shaft. But I didn't realize they are exactly the right size so I am in the process of reconsidering these switches.

Actually Grayhill 56DP30 is a little better I think. It has better AC specs and it's actually a little less than 10mm. Multiple vendors have SP12T and DP6T and Mouser has 4P3T.