If these nails could be replaced with say a slot?
The plastic card fits half way into the slot, when its IN a microswitch is operated, when it its OUT, the 'musw' is released and the contact closes.
The state of the switches are relayed thru a cable to your frying area.
If a switch contact shows a close state a LED lights up.
A buzzer/latch using a relay, sounds the buzzer and you cancel the buzzer/latch.
.
I was thinking vertical slots for the cards. How many cards to you expect to use?
Have funKevinAlaska said:Okay... about to out for a 'late' 4th of July party think with family.
FWIW it occurred to me that my "cheap and easy" paper clips+foil idea might well end up more work and more expensive than Eric's scrap bronze strip idea, even if there were no other problems. Not that I've worked it out properly, just speculating.I plan on taking my notes and hopefully when I get back I can come up with some kind of idea to bounce back on you all.
Tomble said:Have fun
FWIW it occurred to me that my "cheap and easy" paper clips+foil idea might well end up more work and more expensive than Eric's scrap bronze strip idea, even if there were no other problems. Not that I've worked it out properly, just speculating.
Also I think the polarity of my version would be opposite (switch would be on when the card is in) and would probably need a little transistor inverter or such to get the same behaviour.Each of those might be only about 5p or equivalent (10c?) but might end up a lot of soldering if you've 50 of them. Not sure how any of this might fit in with Eric's matrix suggestion though, got a headache this morning so I can't think clear. Maybe matrices suffer from collisions(?) though, if you expect to have multiple cards out at once.
One medium-tech answer to the lots-of-wires problem (for either switch type) if PICs are out of the question: maybe a couple of shift registers, a clock generator and some other logic chips might make a workable multiplexer to get a collision-free representation of the cards over 2 or 3 lines. No I don't have a design for such a thing ATM XD And yeah, digital circuits might be a PITA to work with
Meanwhile, I realise I don't entirely understand what the situation is with this, I think I missed some earlier thread: is it that you've got one booth where people order stuff and get given the cards from the switchboard, and another somewhere further on where they bring the cards to to collect their order ("fryer's booth"? Food?) from you?
If so, just how far apart are these booths? Perhaps there could be an even simpler approach. And is it necessary here to get the cards back to the ordering booth? Or switch off the indicators for an order you've got ready which hasn't been collected yet (so they don't distract you)? Any possibility of an overstretched booth attendant putting a card back in the wrong slot?
ericgibbs said:maybe a couple of shift registers, a clock generator and some other logic chips might make a workable multiplexer to get a collision-free representation of the cards over 2 or 3 lines.
hi tomble,
Same way as I would do it.
hi kevin,
If you go to the scrap yard, look thru their cable dump, quiet often they have cables ready for burning off, for the copper.
A few metres of old telephone multi-core twisted pairs would be ideal.
You will be suprised what 'goodies' you can pick up, just for the scrap value cost.
Eric
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