Optical Attenuator/switches... any one ever even seen these. Opto isolated FETs

[Mooly]

With all the recent threads on attenuators and the "lightspeed" etc, wondered if anyone had ever come across this type of device.

First saw these in Elektor around 25 years ago (in an AGC circuit) and never seen the devices since.
http://www.nteinc.com/specs/3000to3099/pdf/nte3085.pdf

Wonder how they could be made to perform... noise/tracking etc. 100ohm to 300meg ohms is the quoted range of "resistance"

 

[Nrik]

That surely looks nice

 

[east electronics]

hei mooly ...ever had in your life an nte thing that works properly ??? ...

 

[gfle]

IS610 is the original part.
http://pdfdata.datasheetsite.com/web/59082/IS610.pdf

 

[Mooly]

hei mooly ...ever had in your life an nte thing that works properly ??? ...

can't recall having come across the NTE brand before for DIY parts... might have some old germaniums marked NTE, not sure.

You had bad experience ?

 

[Mooly]

IS610 is the original part.
http://pdfdata.datasheetsite.com/web/59082/IS610.pdf

Thanks for the link... keep thinking back to the old Elektor mag (summer circuits ?). Was it a dual or quad device even. Wish I had kept a lot of the old mags now.

 

[krachkiste]

I'm not sure if I fully understand your question.
Do you mean, specifically come accros this NTE thing? No.
But I've used the panasonic photomos switches, which are optically isolated FETs.

 

[CBS240]

I like the IL300 from Vishay. It has two matched photodiodes so that one of them can be used to servo the LED in order to linearize its characteristics. Great BW too. I have played with it in both photoconductive and photovoltaic mode. I use a couple of them in my latest amp circuit in photoconductive but only for DC bias control, not for signal coupling. I wonder if it would be possible to use one in place of the input cap? I am seriously considering giving it a try. One thing I hate in SS amps is coupling capacitors of any kind. The input cap is a requirement but if I can replace it with one of these linearized opto-couplers it would be cool. Hmm, maybe I should test it as an input coupler and see how it sounds first.

 

[poopydoopynoopy]

nielsen media research used to use those for metering video game switches and other devices...

 

[Mooly]

Some interesting devices out there for sure. The IL300 is another new one to me... thanks CBS240

krashkiste... The photomos relays are interesting... I remembered this thread a while back, have a look at post #6

http://www.diyaudio.com/forums/solid-state/155939-mosfet-relais.html

Any photomos ones high enough rated for this application i wonder.

It's good to see what's "out there"... you never know when you have an idea that can use it.

 

[krachkiste]

there is actually a "driver" IC (also from the panasonic phomos series) that enables you to build an optically isolatet FET relay out of the discrete FETs of your choice.
(http://pewa.panasonic.com/pcsd/product/pmos/pdf/mosfet.pdf)
I stumbled over it recently in this thread:
http://www.diyaudio.com/forums/soli...-amplifier-non-feedback-production-ready.html

hope I'm not telling old stories

regards,
krachkiste

 

[Mooly]

hope I'm not telling old stories
regards,
krachkiste

Not at all... that looks the perfect (never perfect is it ) missing link for a project of mine... DC offset protection without the normal integrator delay.

Relays are the weak point (speed and contact arcing)... so using FET's and a photo voltaic driver could be ideal.