| Electronics > Projects, Designs, and Technical Stuff |
| Having fun with discrete transistors |
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| schmitt trigger:
The key to run bipolar transistors that fast was to keep them out of the saturation region.....consumed a lot of power though! |
| soldar:
--- Quote from: schmitt trigger on January 10, 2019, 09:16:14 pm --- 2N2646 unijunction transistors. --- End quote --- Gosh, I still have a few which I have kept over the decades... I believe I have not used one in decades nor seen any new designs using them. Are they even made any more? I doubt it. They are really of very limited use and 555 chips or others can be substituted with advantage. |
| schmitt trigger:
The 2N2646, having a metal can, has long been obsolete. The plastic versions 2N4870/ 2N4871 are still available. Though not widely available. |
| james_s:
I like UJTs, I remember using them to build lamp flashers, it can be done very easily. I have an old Heathkit wind speed/direction display that uses a UJT based oscillator to clock the display latches. |
| Circlotron:
Next, how about an oscillator using an SCR and a resonant tank? These kinds of circuit techniques are becoming lost in the sands of time. And what about a tunnel diode doing something? |
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