I found a bag of diodes in my parts box but I'm struggling to identify them. Google does not seem to know the part. They have a labeled with "TFK" (top) and "S 191 D" (bottom row) written on them.
I first thought they are 1N191s but they look more like hefty rectifiers to me. In the attached photo, a 1N4004, for comparison, is on the left and the mystery part is on the right. I've tried one in a simple test circuit (really just connected the diode in series with a resistor) and measured the forward/backward voltage and it seems to behave much like a 1N4004, at least with small currents < 100mA. I suspect the parts may be quite old.
Thanks for the info! Still trying to find the datasheet, but I'll take your word on it that it's hefty enough for most uses I have. Actually using the diodes on a breadboard is a little difficult because the wires are almost too thick to fit in the connectors.
raschemmel:
Do you have a scope and a current shunt and a variable power supply ?
Unfortunately no. I've been planning to buy a scope and a good lab power supply for some time, but there are so many models I've been unable to decide which one to get. Any recommendations? Total for both should be < $1000. Out of interest, how would I measure the properties of a diode with that setup?
@Paul: I cut the wires but I didn't notice anything special. The material looks the same as in those 1N4004s.
Find a similar diode.
Do you have any calipers to measure the lead diameter ?
Find a similar rated diode and look at the "Test Circuit " on the data sheet.
It's a 2 to 20 uS pulse with a load within the rating .( resistive and inductive)
Your looking for turn on response and turn- off response.
Good power diide test waveforms and test setups or test circuit.
First measure the lead diameter, diode length and width and record thise values.
Google power diodes and compare dimensions (at the bottom of the data sheet).
Look at test circuit when you find a match.
SCOPE SETUP:
ch-1 => cathode of diode
ch-2 => anode of diode/INVERT (or SUBTRACT)
SELECT : ADD (or SUBTRACT)
Hi PetriH...
If you just want to rectify a lowish voltage at 50/60Hz pretty much anything will do if it will handle the current.
Anything fancier, don't chance it - buy something rated for the job you want. (Most) diodes are cheap.
And there are loads of different sorts. Schottky, Gunn , avalanche, zener, step recovery, PIN .... the list goes on and on.
While that may be true, I have done diode testing and just for the record, that's what the tests are for.
If done properly, it is possible to ascertain if a particular diode is adequate for a job. The fact that you don't have the datasheet doesn't mean you can't test the diode. You do usually need a scope but even that isn't absolutely necessary. There are ways to collect data without one.
fair enough if characterising diodes interests you .. You'd have a job with a psu, pulse gen
and scope to test a step recovery or Gunn diode at 10+ GHz though . I designed rf for years, and some rf diodes are pretty weird.
fair enough if characterising diodes interests you .. You'd have a job with a psu, pulse gen
and scope to test a step recovery or Gunn diode at 10+ GHz though . I designed rf for years, and some rf diodes are pretty weird.
LOL ! ;D
Ok, just for the record, that is not what I meant. The OP described what looked like rectifier diodes.
Does THIS look like a garden variety rectifier diode ?
