Clarification on Gen3 Opto mod?

First off I'm currently working on modding and collecting all those loose electronics for a Gen 3 Mendel; I broke down and got the Gen 3 kit (motherboard V1.2, 3X Stepper Drivers V2.3 and the Extruder Control V2.2) I need to produce 6 Endstops on my own (as well as figure out what other random cables and bit I haven't realized I need yet -____-)

I am a student with very little money to spare on the smaller pre-made boards and such; BUT I do have access to tons of electronic components for free. My understanding of circuits is pretty basic, but given a schematic I can usually make do. I've just hit a bit of a wall.

My school doesn't have the 5-Pinned H21LOB switches in stock but is does have the 4-Pinned TCST2103 Optoswitch!
If I had the premade PCB it would be simple, snip here and connect there. I just cant QUITE seem to figure out exactly where those to cuts would be correlated on the Schematic so I can strip board them.

If someone with a little more know how could employ a little paint magic and alter it for me I would be extremely thankful.

Why not go for mechanical endstops? They are much cheaper and more reliable, in my experience. Also, you really don't need more than 3 endstops for one system, to use them for homing (MIN-endstops). You could even run without endstops if you so please, although the Z axis is a bit of a pain to home manually.

If you still really want to use opto endstops, I have six techzone endstops laying around after changing them for mechanical, and I could sell them to you dirt cheap.

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-Nudel
Blog with RepRap Comic

Generation 7 Electronics Endstops are compatible to Gen3, if you watch out for the different pin layouts on the connectors.

Also, I don't share Nudels good experience with mechanical endstops. Their cabling is like an antenna and trigger sometimes just by catching up electromagnetical noise being around. So, if you use mechanical ones, use at least shielded cables.

The later isn't to promote Gen7, just the result of a few hosed PCB millings.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Hi I have just had a similar problem that one of my opto end stop PCB v2.1and H21LOB has failed and I can't find them anywhere, including ebay. Heres what I did - replaced the H21LOB with a OPB625 from farnell. Bend pins 3 and 5 and it fits in the holes, with just a little stand off from the PCB. Changed R2 to 47 ohm and removed R1 as they have a 10k pull up resistor. They seem to work ok. these work the same way as the H21LOB i.e. inverted, so you don't have to change your firmware config setup.Photo of OPB625 mod
Another way is to replace with a TCST2103 and cut the track as shown here Opto PCB MOD R1 changed to 1k Ohm R2 to 180 ohm, R3 to 2.2k Ohm.
I found however I had to put R3 from the LED and connect the other end to ground rather than to the hole marked on the PCB (Sig) that way the LED lights when the opto switchs. This method will work opposite to the H21LOB or OPB625.
Photo of TCST2103 Mod
Hope this helps people.

Edited 2 time(s). Last edit at 03/07/2012 05:04PM by bobert.