High Speed Optocouplers

Hello All

I am a newbie with absolutely no idea about electronics, so am in need of some help.

I have some 1um SINO KA Series Glass Linear scales.
I wish to splice into the signals, using optocouplers to feed into a second device.

I have Signals A, B, Z.

The Manual to the glass scale Says:
+5v(+-5%) 80ma
Maximum of 60cm per second

The DRO display console showing the scales position says:
Allowable Input signal: TTL square wave.
Allowable input signal frequency: >100K Hz
Power voltage: +5v
Signal: TTL Square signals are sent out from two channels with a phase difference of 90degree (with zero position signal) current 50mA

The device I am trying to optocouple to has internal resistors pulling logic High by default, +5v 100mA and max 500Khz input.

The scales would be powered by the DRO +5v
and the optos output side by the device +5v

I have directly wired the scales to the device and it works.

I need to know what opto to use, and it needs to be high speed to handle upto 100 or 500Khz.

Thanks
Carl

You get more help if you had a circuit to look at but I would say any 4n35. I use 2 of them for a sound card scope I made.

Thanks for replying

I have had some outside help, here is the current info:

"It sounds like you DRO could run into trouble at the maximum federate. 100KHz at 1micron resolution is 100,000 x 0.001 = 100mm/sec which is not very fast. You may lose count if you go any faster although I bet the cut-off frequency is probably quite a bit higher.

If you have an opto with 3uS switching time, the best you could hope for would be 6uS for a complete cycle which is 1/6e-6= 167KHz. In reality, this wouldn’t be any good even at that frequency because the signal would look more like a sine wave than a square wave ie it would only just crawl up to a logic 1 in time to slowly sink to a logic 0 with no clean edges. This is more like an analogue signal than a digital one.

Basically the brain Device can cope with 500KHz at say 1um resolution ie 500e3 x 1e-3 = 500mm/second. You need to decide how fast a traverse rate you require and the resolution to work out the max frequency."

Does this help, any comments fom other members on Opto model numbers would be most welcome at this stage, I guess with the Brain Device maxing out at 500Khz, this would be the upper frequency range for the optos range?

Thanks

Hi be80be

Just seen your reply post, I have looked at the 4n35 and the PC817, PC900 and currently looking at 10M/bits sec types, I’m not the expert on these things, so I am hoping members would be the best ones to decide on the opto model.

Oh and the circuit diagram is
Two DB9 connectors Male and Female but passing through, keeping the same physical location on the pins. Like an extension cord.
3 of the pins would also be taped into to be individually opto isolated to give another output.(1 input, 1 output, 1 opt isolated output.)
The optos would be powered inside the DB9 to DB9 housing, emitter side by the DRO also powering the Scales. With the receiver/opto output side powered by the second device.

Hope someone can understand this, but circuit diagram not drawn yet, this is all supposed to fit inside one of those DB9 to DB9 housing, using some thing like a SO-8 solder on opto package.

Thanks be80be

hi,

I web searched for high speed optocoupler

Lots of hits, this for example.

High-Speed Optocoupler