Opto-coupler choices driving me insane!

[cdev]

Which opto-couplers offer the fastest response with very short 3.3 volt pulses?

[T3sl4co1l]

How fast is "fastest"?

Optos don't look good above 10Mbps (~100ns pulse width), fiber optics aside.

Tim

[cdev]

This is 1pps from a GPS chip that I want to have available to its computer's GPIO, and the problem is - if I use the output from the module as is, it causes RF noise for some reason, a little blip once a second. So i want to opto-isolate it. 

Its not an official 1PPS output, its a 'bodge wire' so to speak connected to the pin where 1PPS appears , added by me. Its a $10 USB GPS dongle - the kind that doesn't normally have 1PPS.

Its quite a decent GPS, especially for the price, and pulls in satellites really well. It just was not meant to be used for 1pps -

before I waste people's time here I need to put it on my scope and see what's going on. This problem predates my owning a real oscilloscope.

Opto-coupler seems like the thing most likely to make it noise free. Just a very short wire going to the CP2102 (another non optimal solution) radiates a little RF blip throughout the house.

[HwAoRrDk]

Okay, so back again.

I realised I was being a dumbass and worrying about nothing with the reverse voltage business.

So, I ordered a few opto-couplers and began to do some experiments on breadboard. Unfortunately, I began to blow the opto-couplers left and right. The LED sides were dead. Huh, what gives? Maybe too much current, so changed the resistors to allow the bare minimum - 10K both sides. No dice, optos still failing after a while. Okay, maybe I do need to handle reverse current after all?Put some 1N4148s in series. But blew another couple of optos! Alright, in parallel then. Nope, more dead components.

I was tearing my hair out at this point, double-checking everything in my test circuit. WTF, do I have a bad batch of opto-couplers or something?

I mentioned my problem to a relative and they told me how I could make absolutely sure to prevent reverse voltage problems using 3V zener diodes in parallel. I was about to order some zeners (and more optos!) when, after staring for too long at the same circuit diagram I posted last, I suddenly realised what my problem was!

The ****ing switch is not perfect, and on the odd occasion (particularly when mashing on the buttons) is making a short circuit path through a pair of optos. The LEDs were being killed by excess forward current, not reverse!

I can't change anything about the switch, so I thought I need to put some current limiting in elsewhere. I think on the ground pin off the switch - perhaps a 1K resistor. So that'll make 11K total (assuming I continue to use 10K) on the LEDs in normal operation, which doesn't affect much, and in case of switch shorting, max of about 10mA through the LEDs. Sounds good?