Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

whats the fastet opto-isolator avilable ?

Status
Not open for further replies.

max_imum2000

New Member
i need to add an optical isolation stage to the parallel port of my computer to control some stepper driver units.
whats the best avilable that i can buy with decent price

thanks
 
Best available & Decent price don't usually go hand in hand. Maybe try looking at the iCouplers from Analog Devices? They aren't opto-couplers per se, they use mini-transformers rather than optoelectronics.

What speeds do you need, how many devices do you need in parallel, and what driving capability do you have (ie. to drive the optocouplers).
 
Last edited:
Can't you use a pulse transformer?
 
max_imum2000 said:
i need to add an optical isolation stage to the parallel port of my computer to control some stepper driver units.
whats the best avilable that i can buy with decent price

thanks

Some years ago I recall a ham magazine (QST) publishing a circuit on a regenerative receiver that used an HP optical isolator to pass the feedback signal to keep the detector just a verge of oscillation. I seem to recall this being a 7 mhz receiver, so the isolator selected was at least that fast...

Lefty
 
You can get opto-couplers that pass video signals quite happily, so you're looking a good few MHz for that - but you need to use the right type, and use them correctly.

A stepper motor doesn't require anything fast - although I would use the serial port and a PIC to drive the stepper motor, rather than use the parallel port and the PC doing the work. Assuming you wanted it opto-isolated?, then you would only need one instead of four!.
 
well... you can get very fast opto's but you pay (I'm talking about $90 a pop, hemitically sealed and fantastic!!!)

however... there is something else that looks promosing and that is magnetic-isolation chips.

Two types
type #1 a mini-XFMR on-chip (basically an SOIC with a pulse-transformer innit, made out of the tracks!!!)

type #2 using GMR elements (of which there is the latching and passive type)

THe GRM type boast silly-speeds over opto's BUT early gen had issues! very susceptible to supply-variation and some other not well documented annoyances

I have tried using the GMR type when they came out (the latching type), these were VERY quickly replaced with opto's and a massive web of mod-wire

I keep getting hassled by the Rhopoint rep to try the GMR-passive type (since I bitched at him for not explaining all the problems with the other type.. in all fairness they wern't really known... teach me for going for very new tech)
 
High speed as measured by frequency and low delay as measured by time are two different features of opto isolators. Which one do you think will be more appropriate for your purposes. The HCPL-0710 has a propagation delay of 40 nano seconds. We use them for isolation of CAN transceivers. They are more expensive than 4N25's but in the dollar range they are still affordable.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top