Its a real Mystery. Hummm Someone must know..I'm not aware that diodes were ever packaged in a TO-92 package. Could it be that they were using the breakdown characteristic of a BJT in place of a zener diode.
Voltage referencedevicesare a lot more than just diodes, that is why they have an "IC" number in the circuit. And often the remaining leg was used for an adjustment function, on sum versions.I'm not aware that diodes were ever packaged in a TO-92 package. Could it be that they were using the breakdown characteristic of a BJT in place of a zener diode.
OMG, Thanks all so much!! I am so happy to finally resolve this.. Cheers to you all, this is the best Forum.https://www.lost-manuals.com/manufacturer/Huntron_Instruments/HTR_1005B-1ES
It's an LM336BZ-2.5 from the parts list.
The TL431. https://www.ti.com/lit/gpn/tl431I'm not aware that diodes were ever packaged in a TO-92 package. Could it be that they were using the breakdown characteristic of a BJT in place of a zener diode.
That's not really a diode, more like a comparator and a transistor.
by Duane Benson
by Duane Benson