Pro Audio Design Forum

Thanks for sharing this. Your file cabinets are a treasure-trove. Though the center-tapped LDR might not be available (VTL5C?2) I think you could get pretty good linearity by using two LDRs with series-connected LEDs. I've seen some modern optoisolator linearization techniques based on your circuit....

BTW I see "RoHS By Exemption" on a lot of items listed at Mouser.
They may have gotten an exemption for CdS cells.

Thanks Brian.
Did you have to force it to the Programs (x86) Directory?
It looks like a nice free program and worth trying.

Thanks to everyone for contributing to this thread. We haven't heard from JP in awhile... One quick question... any thoughts on common mode issues with matching/tracking errors between the two LDRs? I realize the question wasn't posed to me but I don't think the CdS cells impact common mode rejectio...

Slightly OT but one of the things I found in our 1954-era two-wire home was grounded boxes and switch frames that were near water. Those switches and boxes had solid copper which extended to cold water - also copper. I also found the gas heater had a ground lead running from the attic through the ch...

So what platform are you running the old Eagle on?
Will an OS obsolescence eventually force an upgrade?
Some of the stuff I still use runs on XP.
Not much but some.

I think figure 24 intends to show it differentially, though the way its drawn it looks like neither IH or IR pass through the core.



The LM1851 GFI is drawn better.

Thank you for posting this and following up.
I know that I never tried this because, using the 1510/INA217, 1570 etc., there is no access to that node.
With a discrete front end it seems very simple to do.
So you going to share the final schematic when you're done?

Cool!

They still have the two signal layer Freeware: http://www.cadsoftusa.com/download-eagle/freeware/

And there's a $69 version as well. http://www.mcmelectronics.com/manufactu ... E/01008405