Posted: 11/13/2004 6:31:35 PM EDT
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I bought a parts cabinet at the flea market, and in one drawer was a bunch of parts. The package is metal covered, 3/4 " square and 1/4" thick, with a 1/8" hole through the center. It appears to be meant to be mounted with the 4 leads "up", held with a screw to whatever chassis. The manufacturer is Unitrode (now owned by TI, the site refers to power management devices). The 4 leads are basically small eyes coming out of the epoxy and are numbered with a digit 1 through 4. Connecting pairs of leads, some would show a 100 ohm path. I the idea these may go back to the 80s, and long purged from their web site. Googling isn't getting me anywhere, and ideas on what the package type is called? Or a lead to a site with a good, older reference guide? Thanks, PRK |
| My first guess would have been a bridge rectifier, but you mentioned 100 ohms between the leads. Maybe it is a wheatstone bridge. Or it is 100 ohms between 2 leads and each pair is shorted? Then it could be a 100ohm 4 wire RTD (usually at 0 degC tit is 100 ohms though). I'll look around....do you have a picture? Or it could be a transformer or common mode inductor, and each coil happens to have a resistance of 100 ohms... |
Identifying marks? Numbers? Do you have a digital camera 
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Probably looks somthing like this 
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Well.. if I remember correctly from my electronics classes.. a diode creates somewhat of a one way street. current can flow one direction through the diode however it cannot (most of the time) travel through the other direction. "An electronic device that restricts current flow chiefly to one direction" If you use an ohm meter to test the diode it will show a certain amount of resistance. |
A diode is a non-linear device, which means that the resistance isn't constant, but instead depends on how much current your test meter is sending through it. (This is why diodes aren't rated in Ohms, btw). Since this particular diode array is a high-current device, it will only be in full conduction (e.g. have a low resistance) when high currents are sent through it - much higher currents than your meter is using. If you had a meter capable of running several amps through it, the measured resistance would drop to a very small value. |
That's very similar. The leads on this one look more recent, on mine the leads are wires formed into eyes. I forgot to mention, below "Unitrode", are two number groups: 655 and 009 . The probe reversal is a good idea. Bridge rectifier does sound likely. ETA the picture software isn't on the ole computer, and might not be possible. |