Valve Itch phono

Hi,
Thank you.
Why this specific one?

Because of it was mentioned by Salas.

Btw I sampled some different 5-6 IR leds the other day. Quite a large difference in Vf drop, up to some 40% if I remember correctly. Also one has to make sure its stable down to half a milliamp or so. Not everyone are.

Was they different part numbers, or different specimens of the same part number?
 
Concerning the IR LED

The HIRL5020 recommended by Salas in unobtanium. It's rated 100mA forward voltage and 1.45-1.7 forward voltage.

There are other LEDS with similar specs stocked and there are LEDS with better-looking specs, rated 100mA 1.2V, 50mA 1.2V and 20mA 1.2V.

Before ordering many part numbers with various specs, which ones should I buy in order to test them?
 
The specifications from the manufacturers are often not consistant, for example Vf is not at a standardised current so it takes some figuring out in the datasheets and also testing to figure out.

If I have the time some day I will do the ones I have at 0,5, 1,0 and 1,5mA so we can se Vf drop and linearity at those currents.

You dont need 100 mA.
 
I did FYI a quick and dirty on one sample yesterday. Family wanted me elsewhere so I only had time for that, we'll see if I can sneak away quick in the weekend to do some more samples.

The test setup was bench supply plus side - one matched 10 k resistor - IR LED - bench supply minus. One DMM over the 10 k resistor and another over the LED.

To get 1,5 mA over the LED I adjusted the bench supply until I had 15,00 Vdc over the 10 k resistor. Then I did 1,0 mA same way, 10 V over the resistor and then 0,5 mA, ie 5 V.

I wrote down values over LED to test low current stability and linearity. The first and only I ran, dont remember brand or number now, was stable at all values and varied some tens or hundreds of microamps so it seemed fairly linear. Yesterday I found only two different brands, I have some more somewhere.

Vf drop values was somewhere between 1,0-1,1 V, forgot the note at home. Brb with more samples later. Cheers.
 
Right Joshua_G, heres some samples:

First out 3 samples of HIR7373B/L289 from Everlight Electronics
https://www1.elfa.se/data1/wwwroot/assets/datasheets/HIR7373B-L289_eng_tds.pdf

0,5 mA: 1,240 V 1,248 V 1,236 V
1,0 mA: 1,267 V 1,271 V 1,264 V
1,5 mA: 1,282 V 1,283 V 1,280 V

Linear and consistant but fairly high drop.

Then some IR 333/S2 from the same firm:
https://www1.elfa.se/data1/wwwroot/assets/datasheets/07522519.pdf

0,5 mA: 1,027 V 1,028 V 1,040 V
1,0 mA: 1,054 V 1,056 V 1,069 V
1,5 mA: 1,066 V 1,072 V 1,085 V

Also linear but much better Vf drop for this app.

And then some 1N4148 for fun:
https://www1.elfa.se/data1/wwwroot/assets/datasheets/DIOTEC_1n4148_eng_tds.pdf

0,5 mA: 0,578 V 0,577 V 0,578 V
1,0 mA: 0,611 V 0,611 V 0,611 V
1,5 mA: 0,632 V 0,633 V 0,631 V

How about that for consistency? Pretty linear to.

Well, the IR 333/S2 seems like a good choice for a LED if you can get it. I'd try the 1N4148 and maesure THD on the whole application and see if there is a noticable differance.

The current values is choosen for different 6N2PEV samples you might get your hands on.