I've used TLP18* as generic optocouplers, well available in SMD packages. E.g. TLP184 is quad open-collector optocoupler. Not very tiny but significantly smaller than 4x DIL6 or its SMD "gullwing" counterpart. Quite cheap and performance similar to 4N25 or 4N35 types, and if I remember correct they do not provide external "base" connection, or at least not in 4-lead packages.
Another IC-family which is quite useful, altough not so inexpensive, is ADUM (
http://www.analog.com) digital isolators: bandwidth upto several Mbps or more, available in different configurations (e.g. 2x RX + 2x TX), capable of logic translation (3V logic to 5V logic and vice versa) and isolation is certified to over 1kV. Few con's are that those are 'active' devices so they need power supply to both sides of isolation barrier, and that they are not very cheap at least if compared to TLP or 4N* series.
Although ADUM's are integrated magnetic isolators they do have totem-pole outputs
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I just happened to find this site and as a short background regarding to myself, I have been interested EFI management for a very long time and I also have build/collaborated several megasquirt projects past few years. It (MS, MSnS, MS-extra) still has some limitations and I am not pleased of its hardware, so I have designed few own PCB versions for that platform, although few latest designs from Bowling/Grippo have been more close to "decent" than previous ones.
I have been working about 10 years as a HW designer in R&D industry, and last 5 years in a consulting/engineering company. Mostly I've been involving embedded electronics and control designs incorporating different kind interfaces to sensors and actuators, and I definitely like to keep myself more analog than digital designer.
Currently I am perhaps little bit too busy to participate fully for this kind of hobbies as I have a (building) construction yard awaiting for next few months. Unfortunately I don't have lots of free time to spend reading threads (until winter
) but I am definitely interested to give you guys help e.g. in terms of reviewing designs, helping out component issues etc...
Seems that there aren't other-than-native design files available - please correct if I'm wrong - and for me it would be nice if a PDF version of the design would be available somewhere.