End of Lifecycle: Our Beloved H21LOB Optical Interupt Switch

So, it appears that this sacred switch thats been adopted into a number of reprap hardwares is no longer being manufactured!

Mouser says that Fairchild ended the lifecycle of the H21LOB and that it is considered "Obsolete"

Same is reported from Digikey and a number of other suppliers....


Does anyone know of a replacement part specific to the H21LOB???

Yes, a replacement would be a great thing. Currently you can still get them on ebay, likely not forever.

Some people apparently use the TCST 1103/2103 successfully.

---

Generation 7 Electronics	Teacup Firmware	RepRap DIY

H21LOB is already out of business for quite a long time. EOL 2006 i guess.

TCST2103 is a usable replacement, however the wiring is a little different as this is not a photologic but phototransistor device. Example wiring can be found in gen6 documentation.

A real drop-in replacement is made by Optek. However this one is quite expensive. I'm sorry, forgot the partnumber

Happened to see this thread a bit late I'm afraid...

I never really understood why the optos went that design path. Considering every printer I've ever scrapped had 4 pin optocouples, this seemed like a really odd part to source.

I built my own opto endstops for my makerbot using 4 pin optos (just generic things salvaged from printers) and a few SMT resistors. CDrom drives, printers, and basically anything that needs to stop at a predetermined location typically has one of these sensors, so they are much easier to find.

I would have to pull them off to draw up an accurate schematic since I don't remember exactly what I did, but it is basically a path of least resistance circuit. There is a pull up (or maybe a pull down?) resistor. The optocouple just overrides the resistor to change the signal state.

I used the GP1A51HRJ00F on mine, which are basically a drop in replacement, with the exception that the mounting holes are perpendicular to what the H21LOB has.

There are still sources for them

There are enough H21lob's available on this world, so there is really no need to panic

Edited 1 time(s). Last edit at 03/25/2011 02:51AM by brupje.

---

---

reprapworld.com
PLA, ABS, PETG multiple colors (3 and 1.75 mm) €16,49 / kg
Megatronics 3.0 €79.99 / Minitronics €37,19