Well, we had a number of threads on this topic, now I finally got around constructing this variant. It’s a cheapo, total cost for each button is 0.19 Euro if you use parts from Reichelt:
LED 8MM XX (LED 8mm (green, red, orange, yellow)): 0.10 Euro
TASTER 3301B (tact switch, 9.5mm height): 0.08 Euro
one drop of superglue, one sheet of sanding paper (graining 240): 0.01 Euro (averaged)
Attached are some pictures of the result (this one uses the orange LED).
How to go about?
Sand off the top of the LED by sliding it over the sand paper lying on a flat surface. Use circular motion for best results. The more you sand off, the flatter and bigger your button will become. This takes 15 seconds.
Bend the legs of the LED carefully according to the grid of your board (grid is usually 2.56mm).
Use a knife or cutter to sharpen the top of the tact switch. See picture. The top should fit between the two legs of the LED.
Place one drop of superglue between the legs of the LED and glue it to the top of the tact switch.
That’s it. Don’t worry about the fragile joint between tact switch and LED - once the item is put into a case, the LED should be secured by the front plate, so no movement to the sides is possible any more.
Another advantage of this: front panel costs are reduced, because there is only one hole instead of two when using LED and switch separately.
Best regards, ilmenator
Edit: fixed a typo and added time it took me for sanding off the LED’s top.
I must thank Ilmenator again for this inspiration!
It’s not the same as demonstrated here, but today I tried a 5mm LED together with a tact button “TASTER 3301B” and a transparent button cap #705191 from Conrad (0,27 EUR) - it works great:
the only problem i have with this design of button, is that the led legs will eventually break. could you not put lengths of multi-core wire on the led legs to make it last longer? great idea otherwise though! ;D
That button cap is exactly what I’ve been searching for for my buttons! Looks nice, thx TK
Random (Mr modnaR) you’re kinda right… Although I suspect it would be decades away, I’m sure the design will stress the LED legs and eventually break them, or more likely, the solder joint. The movement is a rotation around the solder joint as a fulcrum, probably with a fair ellipse due to the downforce. The pins will be rather flexible and the solder itself will be soft (it’s lead), the solder bond with the copper will be quite strong, but the weakest link there is the bond between the copper pad and the PCB fibreglass. I think the trace would be torn off before the pin snapped (provided the integrity of the pin is sustained, ie no oxidation). I mentioned in another thread a good way to bend the wires to help move the stress away from the solder joint and into the pin itself but admittedly it’s not perfect…but I doubt it will be a big problem.
I have been playing with pay_c’s ‘silicone rubber tubing over long tact switch’ trick lately (if you don’t know what I mean, click those links), just took delivery of my new power supply so I’ll need to get a camera next so I can send pics… Long story short, it’s about as cheap as the above, but takes the LED out of the button, and uses the tubing as a light pipe. By slicing the tubing a certain way (not just the angled cut pay_c mentioned, but a few others too), I’ve been able to get pretty good even diffusion of the light, but I was disappointed with the diameter of it, because the tact switch is about 3mm and the tubing takes it to about 6-7mm. All I needed was some kind of clear cap to put over the end, to make it a bit wider …
the led legs (pins would be better off being bent in a curve from the base of the led to the pcb. having a right angled bend in them makes them highly susceptible to fatigue. i think they’ll last less than a decade, but if i’m wrong i’ll be happy for you! ;D
Here my experiences: by using verowire the LED connections can be made flexible enough so that there is no danger that the legs get broken over lifetime.
Verowire is expensive, but allows to wrap the connections between buttons, LEDs and shift registers quickly - compared to ribbon cable I used in previous projects, it only took 1/3 of the time to wire a complete board, since it was not required to deisolate the cables with a cutter - just heat up the isolation
Creating the whole module took about 5 hours.
Here some pictures:
Bottom of the board with all the button connections to the shift registers - you can also see the “Verowire pen” I’m using
Glueing the LEDs on the buttons - they are sitting very solid; later they will be held by the frontpanel in addition
…after I soldered the LED connections - it looks a little bit like tinsel over a christmas tree
The module was working immediately
I’m using Red/Green Duo-LEDs. When both LEDs are lit together, the resulting colour is yellow. So, I’ve three colours now
Disadvantage of this technique: I will have to consider a certain tolerance for all button holes, since it is difficult to adjust the distance between the buttons; the LEDs are not sitting 100% aligned! However, I guess (or hope) that with the frontpanel these cannot be noticed anymore
:o nice pics TK !! The verowire is isolated ?? looks more copper than anything else
What’s that in german - verowire ?? didn’t find something similar @reichelt. ??? How did you connect the leds to show the other color ?? are they connected to a DOUT ??
How did you connect the leds to show the other color ?? are they connected to a DOUT ??
Buttons are connected to a 4x8 matrix, and LEDs to a 4x16 matrix. I’ve written a special driver which allows to control the red and green LED seperately.
how tough is the insulation on that verowire? surely it’ll rub through, won’t it?
No problem here, it takes some time to melt the insulation with a soldering iron
good idea though! what’s the board for?
Together with a second board it will be an extension for MIDIbox SEQ.
