i have attached a the schematic file of what i would like to built.
i have a 20pin header at the top that i use it to attach mu lcd on, and leave me of an other four holes to my pcb for +12v, -12v, GND, 5V. that i would need for this schematic. right next from the 4067 multiplexer is a modulator schematic. but for that i am pretty sure that works. it all ready tested on the breadboard and it works.
it is the multiplexer that makes me a little bit anxious here. i am not pretty sure if i have to get them all parallel powered up or in line ? and if this a good schematic or not.
it is the first time that i am going to send files like that to be printed and the first time to use tools like eagle to so. i am just an electrician so electronics are way out of my league. 
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what i would like to do is having 16 hall sensors and an lcd (16x2) working with a small arduino. so that has to involve a 4067 multiplexer. could anyone suggest if there is something wrong with this schematic? or make any kind of changes that might thing that would make more efficient ?
i wouldn't like to sent the files, wait for a couple of weeks to be shipped back and find out that they where wrong from the first point.
thank you all for rearing this.
