Alternative opto switch??

Hello there!

I'm in the final research stage before ordering everything for my mendel!><

I thought that I could save up some money by doing the optoendstop circuits by myself on a stripboard etc.
The schematic is pretty simple and the components are simple too.
But I have a problem finding H21LOI or H21LOB. Basically I'm looking on ebay for European sellers (to save up from shipping costs & customs) that sell opto switches but I found some others like: that (KTIR0121DS Slotted Photo-Interrupter Opto Switch) or that (Opto H13B1 SWITCH 4PIN).

Does anybody know if they are going to work?

I can't really understand if they have any difference from the classic H21L looking the datasheets and I search here for other alternatives but no luck...

Thanks in advance and cheers from Greece,
John

4 pin optos just have a photo transistor that gives an analogue output, whereas 5 pin optos follow it with a Schmitt trigger to give a sharp switching point and a digital output.

I think the ATMEL chips have Schmitt trigger inputs, so the 4 pin version should work OK, perhaps a bit more prone to cable noise.

I used small micro switches fastened to the bars with P-clips to save needing PCB's. [hydraraptor.blogspot.com]

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[www.hydraraptor.blogspot.com]

Thanks for the fast reply nophead!

Now I can understand the difference between the two version of the optoswitches depending from how many pins they have!

I checked your version with the micro switches but the ones same as your are priced 9€ or £7,42 which is extremely high but nevertheless looks really good and must works good!!

I'll try my luck with the 4 pin version opto switch eventhough, as you mentioned, I might have some noise from the cables...

Just one last thing. I looked on the wiki and probably I'll have to do the extra instructions mentioned on the " ZD1901 Opto Switch " section. It says that I have to cut a trace and shortcut two points but because I'll do the six boards on stripboard, I checked the schematic and I couldn't figure out what are those changes...

I downloaded the schematics from the svn (opto-endstop.sch) but they are for a five pin optoswitch and they are for version 3.0 of the board.

Could anyone attach a link or a picture of the schematic for the 4pin version please?

Have a great day,
John

Edited 1 time(s). Last edit at 06/22/2010 06:14PM by stam.

Farnell do ones the same shape for £0.20 and upwards.

I assume the quality is a lot less. For X&Y they are not at all critical unless you want to recalibrate mid build. I only home when the machine is reset and I build objects with a slightly random start position to even the bed wear, so repeatability is not required.

Z needs to be repeatable to better than 0.05mm though so worth getting a decent switch or opto for that.

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[www.hydraraptor.blogspot.com]

Oh, those are much cheaper then!><

I'll order then some of those to try them too, but how do you connect them to the boards? They seem to have only 3 pins

John

You only use two of the connections but you also need a pull up resistor to 5V, ie: -

Connect the common to ground.
Connect the normally closed to the end stop input and also connect it via a 4K7 to +5V.

Edited 1 time(s). Last edit at 06/22/2010 08:19PM by nophead.

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[www.hydraraptor.blogspot.com]

Ok, I got that!

I'll use the switches for X and Y and I'll make two opto switch boards for the Z axis!

Still, I can't figure out how the 4 pin opto switch is connected to the board. On the schematic here I can't find the trace that is marked 'A' and the holes marked 'B' so I can make the whole circuit on a stripboard

Could anyone attach a schematic or a link with the 4 pin version?

Thanks a lot!
John

Pins 1 & 2 are the same.
Pins 3,4 & 5 are replaced by two pins numbered 3 & 4. Pin 4 is now where 5 was, as there is no middle pin..

Pin 3 is the output (Vo).
Pin 4 is GND.

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[www.hydraraptor.blogspot.com]

Thank you so much hophead!!!

You are really helpful!!!

John

The OPB625 from Farnell, £1.84 looks as if it is compatible. It has a 10k pull up resister built in, so this can be excluded from the pcb. The Vo pin may need to be bent slightly to fit the pcb, but if making on strip board will present no problem.

Do check the pins are numbered the same between HL21LOB and OPB 625.

Have just ordered one from Farnell, actually for a spindle speed indicator for a cnc lathe. If I can find my way back here, will post the findings.
ttfn.