What is the output of this UJT relaxation oscillator circuit?

In summary: Okay, I'll answer the question for you, but you have to promise to do the thinking on the way.The UJT is a voltage controlled device, and its control voltage is VBB.The BJT is a current controlled device, and its control current is IE.The voltage at the base of the BJT is controlled by the zener diode, and is approximately 1.2V. This voltage is applied to the base of the BJT via the 100k resistor.The base of the BJT is also controlled by the emitter current IE.Therefore, the base current will be given by VBB/100k, since the zener current is small and will be neglected.Note that the
  • #36
Oh, sorry

Vout = Vp - Veb
 
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  • #37
Confirmation?
 
  • #38
Femme_physics said:
Confirmation?
Ah, that's looking better. :smile:

Though I'm still wondering what value you'll use for that unijunction transistor's VEB?
 
  • #39
We don't know its value so we can't actually solve it, just leave it as an unknown

We can make the assumption it's 0.7 volts of course...but maybe it's best to stay on the safe side and leave it as an unknown?
 
  • #40
Femme_physics said:
We don't know its value so we can't actually solve it, just leave it as an unknown

We can make the assumption it's 0.7 volts of course...
If you need a value, it's going to be the value of VEB when in the breakdown region, viz. VV. For your problem, VV is given as 2.1V (or maybe 1.1V depending on which question is considered).
 
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