Wednesday, July 4, 2012

Under the Microscope

Cutting Under the Microscope
I think I have past a personal milestone on my forever quest to build ever smaller projects.

I noted the passing, when I realized it was much easier to cut-out my paper models of a new small PCB under the microscope.

The scissors look like huge shears under the microscope.

This new TCVCXO board is required due to pin mounting hole miss-alignment (my error) on the previous PCB. This time I am using the cut-out TO MAKE SURE it is correct.

Alignment Conformation
A straight pin pushed through the holes ensure hole alignment. The fifth pin is at an odd, non-standard location and has caused me trouble.

Note: for scaling, the protoboard holes are 1.0mm in diameter and on 1/10 inch centers.

The paper cut-out now confirms the new PCB layout

This paper image is the same that I would use to create a Homebrew Toner Transfer PCB (if that was my goal) but for this board I will be using the service of (again).

The five Crystal Pin Sockets (see previous post) are installed and ready to receive pins from the new TCVCXO board.

Pin-Sockets Installed
I took this pin-move opportunity to shrink the TCVCXO board even smaller, it is now only 0.34 X 0.5 inches, which is smaller by about 25 percent.

I do enjoy making projects as small as my abilities and eyes allow.

The two bottom Pin Sockets supply I2C Signals (jumper wires will be added on the back side), the next two Pin Sockets supply GND and 3.3Volts (the Propeller board already has them connect to VDD and VSS), and then the new TCVCXO board supplies its 10MHz output to the single Pin Socket (upper Center) to the Processor Crystal Input. The Processor multiplies its input by eight, to supply its internal required 80MHz clock frequency.

The sixth pin socket shown in the photo (upper right) is one of the the standard 5MHz Crystal sockets, which will not be used with the 10MHz TCVCXO board installed.

This is a proven circuit, I am just trying to get the final implementation right.


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