Has anyone used these gems?

[jgedde]

HN3C51F and HN3A51F NPN and PNP matched pairs from Toshiba. So far they seem to be unobtainium, but worth pursuing.

150V VCbo, high and linear Hfe, and a whopping 1 db noise figure! JFET territory for sure...

Here are links to the datasheets:

http://www.bestweb.net/~jgedde/HN3C51.PDF
http://www.bestweb.net/~jgedde/HN3A51.PDF

[darkfenriz]

They seem very similar to popular 2sa970 and 2sc2240 in to-92 case.

[lineup]

Originally posted by darkfenriz
They seem very similar to popular 2sa970 and 2sc2240 in TO92 case.

... and 2SC2240 - 2SA970 are just great low noise transistors
and even though rather low power is recommended
they can take 120 Volt Collector-Emitter !!
Which makes them suitable, without cascoding,
as higher power amplifier input differential dual pair.

Compared to other common TO92, like BC550 - BC560 'only' 45 Volt C-E


Lineup Audio Lab
... uses both BC550 and 2SC2240 in circuits, frequently
... and results are very rarely disappointing

[jgedde]

For the ones I found low power is the word of the day also.

Note that the HN3*** beats the noise figure of the 2sa970 by 2db. Better yet, they are matched pairs (3%) matching. This means it is possible (a good idea?) to not use emitter degeneration resistors.

Since they are also Hfe matched, it means reductions in THD without having to go through the trouble of matching discrete transistors by hand.

I'm designing an amplifier that will use these (if I can find any). I was curious about opinions from those you have reviewed the datasheets.

[lineup]

Originally posted by jgedde
For the ones I found low power is the word of the day also.

Note that the HN3*** beats the noise figure of the 2sa970 by 2db. Better yet, they are matched pairs (3%) matching. This means it is possible (a good idea?) to not use emitter degeneration resistors.

Since they are also Hfe matched, it means reductions in THD without having to go through the trouble of matching discrete transistors by hand.

I'm designing an amplifier that will use these (if I can find any). I was curious about opinions from those you have reviewed the datasheets.

from what you say,
it has to be excellent transistors for input pair in any amplifier
because, there are not too many that can beat up 2SC2240 - 2SA970
or even come out even

but as you wish
I will download and have a look into datasheets

[lineup]

i did have a look at datasheet
and test diagrams

i must say it all look very nice and good

I would say, even though Toshiba have used 1mA for to get good data
I think they work the absolute best between like: 0.5 - 1.0 mA

It is a bit depending on the resistance at the input of your circuits.
Source resistance will a have some little effect due to some little bias current noise in resistors.

But also, of course one factor is what collector load you need to drive with input pair.

Sometimes we need more than 1mA to get good drive of collector loading.

[Jose Hidalgo]

Question : I'm looking for these two components (Toshiba HN3A51F and HN3C51F). I need about 50 pairs. Do you have any URL where I can buy them ? (Europe, US or elsewhere, I don't care).

BTW, I'm also looking for Toshiba 2SA1349 and 2SC3381 (same qty, about 50 pairs).

Thanks in advance.

[peranders]

If the voltage is not so important BC847BS is quite OK as a pair, very cheap also, less than a 1/4 dollar.
http://sjostromaudio.com/hifi_pics/h...363_detail.jpg

http://sjostromaudio.com/hifi_pics/h...L6toSOT363.jpg

[winhill2]

Originally Posted by lineup

from what you say,
it has to be excellent transistors for input pair in any amplifier
because, there are not too many that can beat up 2SC2240 - 2SA970
or even come out even...

This line of parts are in my estimation the lowest-noise BJTs now available (lowest r_bb') that have official low-noise specs**, now that Rohm's 2SD786 and 2SB737 have disappeared.

Sadly the 2SC2240 and 2SA970 (npn, pnp) super-low-noise trannies in TO-92 packages no longer appear on Toshiba's Bipolar Transistors Product List, and have been designated NRND by Toshiba (Not Recommended for New Designs). [link] This means the factory is presumably still taking (large) orders, but they are destined for the dust-bin of history. FYI, last chance, B&D still has some inventory.

But, not to fear, Toshiba offers what appears to be the same (or better) die in SOT-23 packages, the 2SC3324 and 2SA1312. These are stocked by Mouser, and cost only 15 cents qty 100. Their datasheets are fairly complete, including two NF contour plots. The 1kHz plot shows the 3dB contour dropping 35 ohms at 1mA and below 20 ohms at 10mA. That corresponds to voltage noise levels e_n of 1.4, 0.75 and 0.56nV at 0.1, 1 and 10mA. Using the 100Hz plots, we can calculate that the 1/f corner frequencies are about 14Hz, 35Hz and 170Hz, not too bad.

The hn3c51F and hn3a51F dual transistors, original subject of this thread, also appear on Toshiba's official Bipolar Transistors Product List. They come in easy-to-solder SC-74 (6-pin SOT-23) packages, and apparently use the same dies as the 2sc3324 and 2sa1312. Their datasheets have the same two impressive noise-figure contour plots. But even though several years have gone past since this thread started, no distributors have picked up these parts. If we want to use them, we'll have to make a large group purchase. A standard reel is 3000 parts.