geekhack
geekhack Projects => Making Stuff Together! => Topic started by: suicidal_orange on Wed, 25 February 2015, 15:39:01
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I'm in the early stages of planning a board and am thinking about things which look useful, but aren't used in any designs that I've seen. This makes me wonder why not, so I'll ask some people who have some experience - you lot :))
Firstly there is the issue of the left handed numberpad. If a PCB was made with two holes for each switch pin in a figure 8 you could simply flip the PCB over and have a left handed version. If I'm thinking straight it would only need two plated through holes (as normal) plus one extra pad per switch on each side of the PCB so shouldn't add much to the cost.
The other thing is diodes. There are holes in the switches for them and most designs use through hole as they're cheaper, but they are always outside the switches. If they were in the switch they would be better protected (I'm thinking Swill case - PCB in contact with the casing) and the height of the assembled PCB would be reduced, albeit slightly. Filling all the switches with diode pointing the same way is easier than positioning them correctly at random angles on a PCB and the reduced footprint will leave more empty space to make seeing the routing easier - the only disadvantage I can think of is if you need to remove the switch, which is rare. So why aren't they used?
Thanks for any thoughts :)
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I'm in the early stages of planning a board and am thinking about things which look useful, but aren't used in any designs that I've seen. This makes me wonder why not, so I'll ask some people who have some experience - you lot :))
Firstly there is the issue of the left handed numberpad. If a PCB was made with two holes for each switch pin in a figure 8 you could simply flip the PCB over and have a left handed version. If I'm thinking straight it would only need two plated through holes (as normal) plus one extra pad per switch on each side of the PCB so shouldn't add much to the cost.
The other thing is diodes. There are holes in the switches for them and most designs use through hole as they're cheaper, but they are always outside the switches. If they were in the switch they would be better protected (I'm thinking Swill case - PCB in contact with the casing) and the height of the assembled PCB would be reduced, albeit slightly. Filling all the switches with diode pointing the same way is easier than positioning them correctly at random angles on a PCB and the reduced footprint will leave more empty space to make seeing the routing easier - the only disadvantage I can think of is if you need to remove the switch, which is rare. So why aren't they used?
Thanks for any thoughts :)
Reversible PCB's are quite possible:
(http://mechanicalkeyboards.com/shop/images/products/large_537_DSC_1167.jpg)
Putting diodes inside the switches requires that you have to open every single switch to insert the diode. And if you discover on your plate mounted board that one diode is the wrong orientation you have to desolder the switch AND diode pins to open the switch to change it. Then there's the PCB layout issue, you've got more freedom of track layout with external diodes, since you can place them where you want and they won't interfere as easily with the LED traces. Which brings me to the point that you can either have diodes inside the switch or use LED's. Not both, since the LED leads would need to go through the diode...
So, external diodes FTW.
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Thanks, I hadn't considered normal people who just buy switches and fit them when there's so much talk of spring swapping, jailhousing, lube and stickers around here, and I hadn't considered backlighting. I'm learning :)