Anybody know what these are? - UK Vintage Radio Repair and Restoration Discussion Forum

lightning · 26th May 2023, 9:30 am

There are two wires coming from each end.

Apparently they are a "matched set" but what are they?

Still sealed in their bag.

daviddeakin · 26th May 2023, 10:16 am

The look like optocouplers to me (LED + LDR)

fetteler · 26th May 2023, 11:50 am

I wonder if they are 4 wire prescision resistors?

Have a measure and see what you get.

Steve.

elanman99 · 26th May 2023, 3:03 pm

They 'look' like Vactec/Vactrol optocouplers but its hard to see because of the polythene bag.

The Vactec devices are LED-LDR and all the ones I used had cylindrical bodies with two flats but always had a printed-on part number.

Easy to identify internals with a meter

Ian

Craig Sawyers · 26th May 2023, 6:35 pm

I think they could be Fluke, who supplied sets of resistors matched for temperature coefficient and close tolerance. Sometimes they were "aged" to get the resistance value to stabilise. Often funky values like 98.5k.

Anything written on the parts?

Craig

Diabolical Artificer · 27th May 2023, 5:37 pm

If they are Vactrol opto couples they are very much sought after as some vintage studio compressors used them.

Andy.

Keith956 · 28th May 2023, 8:47 am

Might be these - a NSL32SR3 optocoupler. I've used one in the past for a wien bridge oscillator.

https://uk.farnell.com/advanced-phot...-Test-Tools-PS

fetteler · 28th May 2023, 9:53 am

If the OP could make a couple of quick measurements we would know!

To that end I predict resistance between the opposing ends and a short between the pair on each end

Let's see...

Steve.

26th May 2023, 9:30 am	#1
lightning Heptode Join Date: Nov 2008 Location: Stockport, Cheshire, UK. Posts: 712	Anybody know what these are? There are two wires coming from each end. Apparently they are a "matched set" but what are they? Still sealed in their bag. Attached Thumbnails

26th May 2023, 10:16 am	#2
daviddeakin Hexode Join Date: Apr 2007 Location: W Yorks, UK. Posts: 407	Re: Anybody know what these are? The look like optocouplers to me (LED + LDR)

26th May 2023, 11:50 am	#3
fetteler Octode Join Date: Jul 2011 Location: Staffordshire Moorlands, UK. Posts: 1,475	Re: Anybody know what these are? I wonder if they are 4 wire prescision resistors? Have a measure and see what you get. Steve. __________________ Those who lack imagination cannot imagine what is lacking...

26th May 2023, 3:03 pm	#4
elanman99 Hexode Join Date: Oct 2010 Location: Sandiway, Cheshire, UK. Posts: 326	Re: Anybody know what these are? They 'look' like Vactec/Vactrol optocouplers but its hard to see because of the polythene bag. The Vactec devices are LED-LDR and all the ones I used had cylindrical bodies with two flats but always had a printed-on part number. Easy to identify internals with a meter Ian

26th May 2023, 6:35 pm	#5
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,982	Re: Anybody know what these are? I think they could be Fluke, who supplied sets of resistors matched for temperature coefficient and close tolerance. Sometimes they were "aged" to get the resistance value to stabilise. Often funky values like 98.5k. Anything written on the parts? Craig __________________ Doomed for a certain term to walk the night

27th May 2023, 5:37 pm	#6
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,658	Re: Anybody know what these are? If they are Vactrol opto couples they are very much sought after as some vintage studio compressors used them. Andy. __________________ Curiosity hasn't killed this cat...so far.

28th May 2023, 8:47 am	#7
Keith956 Heptode Join Date: Jun 2019 Location: Oxfordshire Posts: 738	Re: Anybody know what these are? Might be these - a NSL32SR3 optocoupler. I've used one in the past for a wien bridge oscillator. https://uk.farnell.com/advanced-phot...-Test-Tools-PS

28th May 2023, 9:53 am	#8
fetteler Octode Join Date: Jul 2011 Location: Staffordshire Moorlands, UK. Posts: 1,475	Re: Anybody know what these are? If the OP could make a couple of quick measurements we would know! To that end I predict resistance between the opposing ends and a short between the pair on each end Let's see... Steve. __________________ Those who lack imagination cannot imagine what is lacking...