A PCB Isolation PCB for a D-Latch/Flipflop

A project log for A Discrete Transistor 7400 NAND GATE

If we did not have ICs then this is what a 7400 NAND gate would look like!

agp.cooperagp.cooper 07/30/2016 at 03:500 Comments

PCB Isolation Failure

Well I had a few hour too myself (my partner is working a double shift tonight - best not to run my CNC machine wile she is at home) so I found the files and knocked up the gCode file for the D-Latch/Flip-Flop PCB. Double the design up for two boards. Just after I started I realised I had not offset the engraver tool (my macro traces the exact outside of the PCB image). So the tracks and pads will be smaller than planned. Too small to be practical and I scrubbed one off while cleaning the board:

I had some other problems that I have not quite figured out. How to mount the board without it bowing in the middle.

I also need a new soldering iron with a smaller tip. My old Weller is 30 years old, electronics has shrunk in that time but not the old Weller.

I am not going to waste my time with these boards.

Another Attempt

Here is the updated design. This time I added a clamp area left and right, and the isolation is properly offset (~0.1mm):

Well it is done. Found a few more set up issues that took some time to resolve:

This cheap Chinese PCB (about $0.50 per 3" x 4") is a bit fragile. May be better to pay a bit more money for better quality.