Mystery Component

The laser diode in a laser printer doesn't have enough power. What you want is the laser from a DVD writer:

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

"Paul Hovnanian P.E."

** Two legs or three?

... Phil

TO-92 Typically three, but yes, good point.

"WoolyBully" "Phil Allison"

** Diacs are made in two leg TO92.

So are constant current diodes, eg:

Phil

Three.

-- Paul Hovnanian mailto: snipped-for-privacy@Hovnanian.com

------------------------------------------------------------------ This is the government our founding fathers warned us about.

On a sunny day (Wed, 30 Jan 2013 20:16:28 -0800) it happened "Paul Hovnanian P.E." wrote in :

Why not measure one? PNP-NPN? Beta Build a curve tracer (Vce breakdown).

:-)

Oh, Ft..

Three legs good, two legs better.

You might try printing some stunning graphics?...

Quick NPN PNP determination with a meter in diode test mode. Allow for base in center or to one side. Fets show a body diode in reverse and touching the meter between G-S will store enough charge to measure some forward conduction D-S. Grab the leads with your fingers to drain the charge and D-S should look open. Even nicer if your meter has a transistor tester function that gives a figure of merit on beta. Nothing beats a curve tracer though. I've got a 30 year old sencore one.

Hard to say if it's a house number but looks like it. When you buy enough or pay enough, vendors will private label. Saw that all the time when I worked with mil-spec stuff.

Have you ever sat on a two legged stool? :)

"Michael A. Terrell" wrote in news:vvidne0Hj9D4JZfMnZ2dnUVZ snipped-for-privacy@earthlink.com:

Even sat on a one-legged one. Used while milking a cow.(to sit on :) )

Which begs ( for ) the question: Has anyone attempted to develop a method for identifying components simply from their characeristics?

Plug a BJT into a test socket, drive the pins, measure the traces, feed the results into a database, and out pops...

"It's a 2N2222A, dummy!"

Hm... is there a way of testing ( say ) a BJT's BVce "gently", that is, so that it doesn't _stay_ broken down?

Jes' curious.

Frank McKenney

--
  Nearly every feature of the American system of manufacturing, from 
  the elements of the new textile machinery to the concept of 
  interchangeable parts, had actually been conceived earlier by 
  Europeans.  But while a few Europeans could see the possibilities, 
  their communities kept them powerless to give their ideas a free 
  trial.  Too many had a stake in the older ways.  Industrial progress 
  in Europe required extraordinary courage to break the prevailing 
  pattern; in America it required a willingness to try the obvious. 
  American genius was less for invention or discovery than for 
  experiment. 
    -- Daniel J. Boorstin / The Americans: The National Experience

On a sunny day (Thu, 31 Jan 2013 13:00:32 -0600) it happened Frnak McKenney wrote in :

Ferry Lon Taim AGOH I designed and build a transistor curve tracer. Was just not much work, and boss wanted one. To keep dissipation in limits you need to use low impulse duty cycle. It could find NPN or PNP automatically. No micros at that time, just relays and logic, output to a normal xy scope.

I am sure with a PC these days you could look up things in a database, and have a better display.

2N650 ?

Cheers

I have one of these:-

Sure, a real BJT (perhaps excepting some RF exotica) can be pushed beyond BVce so long as current is kept low. You can see this quite nicely on a curve tracer if you have access to one. I haven't heard of any problems with devices "abused" in this way, not even MTBF.

BVeb is another matter. Breaking down EB junctions reduces beta, increasing noise and may lead to shortened MTBF. Supposedly forward biasing "anneals", but I don't know if it's completely reversible. IIRC its a function of total-reverse-charge, so you should be able to go into a very limited breakdown for a short time without "significant" damage - perfectly sufficient for a tester.

-F

Apparently Peak-Atlas are marketing a (massively) upgraded version of their

3-terminal component analyser, it has a USB port for connection to a PC (I think it may actually do curve tracing).

The original version I bought about a decade ago will at least tell you if a device is transistor, MOSFET or just a pair of diodes - anything more complex and it'll just report "unrecognised or faulty component".

That would have been BP ... Before Plastic. A 2N650 is a PNP Ge in a TO-5 can.