Uses for diodes

Vermin on two legs.

FOAD.

.... Phil

Thermo-Electric-Coolers.. made with diodes... well alternating slabs of n and p semi-conductor... close enough to a diode in my book.

George H.

No. He is dead. But he was twice-married.

No. Forget them, since they don't exist.

You forgot 'Stabistor' diodes.

We almost forgot one:

grounding protector (for corrosion problems on metal hulls when docked and on shore-supplied power)

I assume he meant *varicap* diodes (used for tuning RF circuits).

The ones with the big black knobs on top?

I never claimed to include all possible uses.

But a stabistor is covered under "Voltage reference."

How does that work?

Is it *really* a voltage reference, though?

Sacrificial anode I would imagine.

I never heard of a stabistor,

Sorta 60 mV/ decade of current... Isn't that like a regular diode? (Diode connected transistor?)

George H.

Instead of grounding the boat (hull, fittings) straight to the third-prong of the power from the dock, that hull-ground gets connected to earth-ground through two or three antiparalleled diodes. This allows the hull to keep its anodic protection (slightly negative voltage with respect to the water) even though the local ground stake is in soil with good conductance to the wet.

More important, is that the forward voltage versus currrent and temperature is tightly specified; the intent is to model the forward voltage of a (usually power) transistor Vbe, so as to bias its base.

If you diode-check a diode, and it's 0.65V at 1 mA, or 0.75V at 1 mA, it's probably good. The BAS17 stabistor, at 25 C, would be out-of-tolerance (too low at 0.65V, and too high at 0.75V).

Stabistors gotta match the particular transistors, so that kind of design in an audio amp means you can't always repair with an 'equivalent' transistor when the original burns up. The clue that your dead amp uses a stabistor, is the little diode attached to the big heatsink.

yes of course..

jamie

obvious John I made a mistake,,. we all do that from time to time..

After 10 hour days, just about everyday, your mind gets a little mixed up.

Varicap

Jamie

It does remind us of trigistor/diac diodes, like the ones used in dimmers. They are really PNPN structures, but they have 2 leads so people call them diodes.

Nobody seems to have mentioned the ever-popular tunnel diode! Back in the '60s-'70s they were the heart of ridiculously-simple FM transmitters. I believe Tektronix used them for fast rise-time calibrators, until they went the way of the unijunction transistor. (Also wildly popular for a while.)

Best regards,

Bob Masta DAQARTA v9.00 Data AcQuisition And Real-Time Analysis