Super simple NPN transistor curve tracer

[merlinb]

I found a circuit many years ago in a back issue of Elektor for making a super simple curver tracer for NPN transistors. I finally rediscovered it today and thought it deserves to be shared. It's extremely clever, I wish I'd thought of it!
https://www.eddybergman.com/2017/06/simple-but-effective-transistor-curve.html
https://archive.org/details/ElektorMagazine/Elektor%5Bnonlinear.ir%5D%201980-09/page/n37/mode/2up

[jorg777]

What are those mysterious part numbers "TUT" "TUP" "TUN" "DUG"?

How can ground drive the X axis?

What is that upside-down "T" marking on the middle of the three outputs?

[GibsonGM]

Thanks, Merlin!

Abbreviations are TUN = "transistor universal NPN"   TUP = "transistor universal PNP"
DUG = "diode universal germanium"

I take that as 'general purpose' transistors

TUT....'transistor under test'?

I don't know what the 'upside down T' is, maybe in the article?

[ulr]https://www.learningelectronics.net/VA3AVR/circ/tuptun/tuptun.htm[/url]

[Kevin Mitchell]

What are those mysterious part numbers "TUT" "TUP" "TUN" "DUG"?

How can ground drive the X axis?

What is that upside-down "T" marking on the middle of the three outputs?

TUT = Transistor Under Test
TUP = Transistor Universal PNP
TUN = Transistor Universal NPN
DUG = Diode Universal Germanium

I assumed the upside-down T was a reference for a ground point for the scope.

edit:
Mike wins.

[GibsonGM]

I did (for once) READ THE ARTICLE Merlin linked to first, LOL.  The Bergman article describes building and using this, and gives definitions 

[Kevin Mitchell]

Instructions are for nerds! For that, my IKEA furniture is inside-out on the first go.
Being used to seeing "DUT" I was able to manage. Though I was stumped on "DUG". Was not expecting a germanium there.

Tempted on breadboarding this. Wondering if that diode can be swapped with a fast switching signal diode (1N914, 1N4148). If not, would a typical 1N34A suffice?

[jorg777]

What are those mysterious part numbers "TUT" "TUP" "TUN" "DUG"?

How can ground drive the X axis?

What is that upside-down "T" marking on the middle of the three outputs?

TUT = Transistor Under Test
TUP = Transistor Universal PNP
TUN = Transistor Universal NPN
DUG = Diode Universal Germanium

I assumed the upside-down T was a reference for a ground point for the scope.

edit:
Mike wins.

Ah, thanks.  I went and read the article.  I think it relies on your scope having inputs which are isolated from each other (they don't share a ground).  I'm not sure all scopes are that way.
I liked WLIP's idea to use a true triangle generator made of op amps to eliminate the retrace.

[GibsonGM]

Tempted on breadboarding this. Wondering if that diode can be swapped with a fast switching signal diode (1N914, 1N4148). If not, would a typical 1N34A suffice?

Got a Schottky?

[PRR]

your scope having inputs which are isolated from each other (they don't share a ground).  I'm not sure all scopes are that way.

No; it does depend on a "floating" 6V supply. Maybe a battery? I just checked: the 'lantern' battery is still available at around five bucks. (There are bigger smaller more-exotic types at higher prices but why pay more?)

[merlinb]

You can use a Schottky diode instead of the germanium, and it also works fine with a 9V battery (and beyond).