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Minor notes on the Zach's Opto-endstop PCBTuesday, July 22. 2008
Two minor notes on Zach's opto-endstop PCB for Darwin...
After doing the final assembly of the y-axis for Tommelise 2.0, I decided to wire in the opto-endstop for that axis before going on to the x-axis. I bought a handfull of the Zach's Darwin opto-endstops shortly after he took delivery on his first batch of these thumbprint-sized PCB's. The two items that I will be discussing here might not apply to later versions of the boards since Zach is meticulous about correcting problems on his board designs on-the-fly, as it were. It would be good to check on yours, however. Over the last few years I've collected an impressive inventory of electronic components. When I started to assemble the board, therefore, I was able to pull the 10K Ohm and 220 Ohm resistors from stock. Interestingly, the board had obviously been designed with 1/4 watt resistors in mind. The 10K Ohm resistor was rated at 1/2 watt and was considerably bulkier than the 220 Ohm resistor that also used in the board assembly. I had to bend the connector wires for the 10K Ohm resistor under it to meet the holes in the PCB.  You can see in the pic how that worked out. It works, but looks awkward. Widening the spacing between the holes for the resistor would help for those of us who use whatever resistor comes to hand make a better job of the board.  More alarmingly, the back-side soldering pads for the resistors (inside the red circle of the above pic) were virtually non-existent compared to the other connectors. This made securing the resistors electrically to the circuit something that I had to do quite carefully and then check with my multimeter to make sure that they were connected. If this problem hasn't already been corrected on the most recent prints of the board, it needs to be. Aside from those notes, the little opto-endstop board that Zach kindly designed for the Darwin printer is brilliant and I am sure will work just as well on Tommelise 2.0. Trackbacks
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