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You can hide airwires only on a per signal basis.  If you turn off the  airwires for ground and power suplies you should have a much cleaner screen. Instead of using ratsnest ! signal_name, you can use the info command on a signal (airwire or trace) in the board window and you will see a check box “Airwires hidden” for that signal in the popup “Properties” window. Click on it and all airwires for that signal will be gone.

Hiding selected airwires
Sometimes it may be useful to hide the airwires of selected signals, for instance if these will later be connected through a polygon. Typically this could be supply signals, which have a lot of airwires that will never be routed explicitly and just obscure the other signals’ airwires.
To hide airwires the RATSNEST command can be given the exclamation mark (‘!’), followed by a list of signals, as in

RATSNEST ! GND VCC

which would hide the airwires of the signals GND and VCC.
To have the airwires displayed again just enter the RATSNEST command without the ‘!’ character, and the list of signals:

RATSNEST GND VCC

This will activate the display of the airwires of the signals GND and VCC and also recalculates them. You can also recalculate the airwires (and polygons) of particular signals this way.
The signal names may contain wildcards, and the two variants may be combined, as in

RATSNEST D* ! ?GND VCC

which would recalculate and display the airwires of all signals with names beginning with ‘D’, and hide the airwires of all the various GND signals (like AGND, DGND etc.) and the VCC signal. Note that the command is processed from left to right, so in case there is a DGND signal the example would first process it for display, but then hide its airwires.
To make sure all airwires are displayed enter

RATSNEST *

Use ‘RATS *’ at the command prompt to show all airwires.”


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I started designing a new board for Alarm security system today, It would be having components that would be running on 3.3V and some at 5V. Although I can power micro-controller by 3.3V, but still I would require it to run at higher frequency, and Max485 wont work on something very close to 3.3V, not even at 3.9V. So I browsed some forums to check what are the best approaches and came across this document called 3V Tips ‘n Tricks by Microchip. Its so useful that I wished to share it here.

Cheers

DOWNLOAD  LINK:
http://www.microchip.com/stellent/groups/techpub_sg/documents/devicedoc/en026368.pdf

3V TIPS  AND TRICKS (mirror on dms)

The Complete Book:
ww1.microchip.com/downloads/en/DeviceDoc/01146B.pdf 

Mirror