[cnc kiwi]

Hi
Can anyone tell me whether or not a fairly standard optoisolator such as
http://www.datasheetcatalog.com/data...TLP521GB.shtml
this one will be able to work as an electrical isolator between my PC/s LPT and my CNC drivers step and direction pins. I wouldn't need any frequencies higher than 5kHz. So, will these optoisolators work fine at such a frequency?
Thanks a lot
cnc kiwi

[martinw]

I wouldn't need any frequencies higher than 5kHz. So, will these optoisolators work fine at such a frequency?
Thanks a lot
cnc kiwi

Dear cnc kiwi,

At 5kHz, an opto-isolator isn't even "getting out of bed". You will have absolutely no problems as regards frequency as long as you stay within specifications elsewhere.

5kHz really is nothing

Best wishes,

Martin

[epineh]

The opto you listed has a forward input current of 50mA from the datasheet, this is a little too much for the parallel port to sink and way too much for it to source, I am using PC817's for IO and HCPL 2630's for step/dir though for 5KHz the PC817 should be fine, it has an input current of 20mA and if you use them active low the P.Port should be OK.

Cheers.

Russell.