Opto Endstop v1.0-ZD1901
An alternative design for the opto end stop used on the Darwin RepRap.
In the Australasian area the most common - and in some cases the only available - opto end stop sensor is the ZD1901, stocked by companies such as Jaycar. This is a 4-lead device and the simplest way to make it work - unless anyone particularly wants to do a board - is to solder it up onto a 6x11 hole piece of stripboard or veroboard. You will need to make 3 for the basic design, 6 if you wish to develop end-stop software for the far ends of the axes.
Aside from the board and ZD1901 you will need a header to match your connectors for the RepRap wiring harness, a 220 ohm resistor and three bits of wire:<div class="thumb tright">
Click on that image to enlarge it, and you'll see that the board has 2 holes and 3 slashes on it. The slashes were engraved in with a dremmel tool, the 3mm holes were started with a dremmel and finished with a low-speed 3mm drill bit. The positions for the holes are found by marking through the retaining holes on the ZD1901 (note orientation of the arrow on the diode symbol of the ZD1901):<div class="thumb tright">
Solder things together using the resistor and 3 bits of wire as per this shot. Note that the pins of the connector will need to be slid half-way out of their tight plastic shroud to solder them in place. Make sure the ZD1901 is fixed securely and as close to the board as possible, as the mounting bolts will otherwise put stress on the board:<div class="thumb tright">
That's it. Mount it as per the standard endstop assembly instructions.
-- Main.VikOlliver - 29 Aug 2007