simple curve tracer

[Pars]

I was thinking about slapping this together on a breadboard:

https://www.fairchildsemi.com/application-notes/AN/AN-6610.pdf

The transistors listed (92PU01 / 92PU51) must be ancient as I cannot find them. I ran across somewhat of a datasheet here:

http://www.datasheets360.com/part/detail/92pu01/3582415256795608549/?alternatePartManufacturerId=0

It looks like a Fairchild KSD882Y might come close? Or could I use anything capable of a bit of power (such as MPSW06/56)? It would seem that an Ic of 2A on the 92PU01 is pretty high for what might be required here?

[swt61]

I have no idea how to read that. I can barely slap one of these together on a breadboard...

 

[cetoole]

I don't think part is gonna be too important here as long as it has sufficient power handling, looks to just be an output buffer to drive the fairly low impedance of the feedback network and JFET.

[Craig Sawyers]

Why not buy a kit from eBay? This (Chinese) kit handles +/-34V at up to 2.5A http://www.ebay.com/itm/locky-zs-Intelligent-curve-tracer-PCB-New-/112168145773?hash=item1a1dbe136d:g:on8AAOSw4shYAujt

Or a Tektronix 575 ebay 262701477638 which will does up to 200V/10A characteristics.

[kevin gilmore]

locky must have run out of metal boxes, that is the same one just as a bare board. (not that the boxes are really very good anyway, but are needed as a heatsink)

that Tektronix transistor tester is all tubes, and loads of fun to keep working.  i'm sure lots of unavailable tubes inside. Still a great piece I used one a bunch

[Pars]

Yes, if I wanted to get serious about it I would buy the locky_z kit  (read about it on diyaudio as well). Marc (luvdunhill) has one and did some jfet measurements/matching for me. The Tek 575 does look like fun (in a special sort of personal hell way :)), though it always has seemed odd that old tube stuff is probably more supportable that old SS stuff as some of the devices may have been MD'd with no replacements available (Counterpoint MOSFETs come to mind, as well as the one chip in the Tek 2465s).

As for the transistors in the Fairchild app note, it looks like 2SD1801 / 2SB1201 are equivalents and available from Mouser.

Edited November 26, 2016 by Pars

[kevin gilmore]

Actually there are a number of chips in the 2465 that are obsolete. And that goes for just about every single tektronix analog scope including the mainframe ones. Sucks. I own 4. There is a guy in Greece that repairs them and seems to have infinite amounts of stock of parts.

[Craig Sawyers]

On 11/26/2016 at 0:29 PM, kevin gilmore said:

that Tektronix transistor tester is all tubes, and loads of fun to keep working.  i'm sure lots of unavailable tubes inside. Still a great piece I used one a bunch

39 of them. And two transistors (both germanium). I have two (don't ask) one with the hernia inducing 175 high current unit (internal wiring is welding cable). First time I used it I stuck a random TO220 on it, and without much effort at all blew a red hot heatsink tab across the room in a hail storm of hot epoxy shards.

I've just resurrected a 576 - a much more useful all transistor tracer. Tek went through a brain dead period when they stopped wax potting their HV transformers and went over to epoxy potting. Alas in the late 60's epoxies were not too well developed, and degrade. Transformer overheats and then crowbars the LT supply feeding the oscillator. Tek woke up to this issue pretty quick, and soon turned over to silicone potting, which worked much better.

So I rewound it. Bit of a faff, particularly the 1400T of 40AWG wire on the 2.7kV secondary. I wax potted it, and the 576 now works perfectly - needs a re-cal though.

Sawyers re-wind in place. Left over ptfe sleeved wire lurking around from my T2 build