UJT QUESTION
The data sheet for a 2N2646 Unijunction Transistor gives the intrinsic stand-off ratio η as 0.65. If a 100nF capacitor is used to generate the timing pulses, calculate the timing resistor required to produce an oscillation frequency of 100Hz. HOW DO I SOLVE THIS

 

Welcome to AAC. This looks like homework, and so we need you to show your best effort at getting as far as you can. That let's us see what your approach is and where you are going right and going wrong. We won't provide solutions for you, but we will help you learn how to get there yourself.

 

Do you understand how a unijunction timer works?

 

This may be helpful. note that you should be able to use the time constant of the resistor in series with the cap to determine the time constant of the RC, and from that, determine when the UJT will fire based in the intrinsic standoff ratio. Formulas for intrinsic stand-off ratio and more is in link below.
https://www.allaboutcircuits.com/textbook/semiconductors/chpt-7/unijunction-transistor-ujt/

 

UJT QUESTION
The data sheet for a 2N2646 Unijunction Transistor gives the intrinsic stand-off ratio η as 0.65. If a 100nF capacitor is used to generate the timing pulses, calculate the timing resistor required to produce an oscillation frequency of 100Hz. HOW DO I SOLVE THIS

I would say the data is insufficient. What is the supply voltage?

 

Many years ago I used PUTs (Programmable Unijunction Transistor) but I never used an old unijunction transistor.
Does anybody use a unijunction transistor anymore?
Then why is this teacher asking the student to find the datasheet of an antique 2N2646?

 

Many years ago I used PUTs (Programmable Unijunction Transistor) but I never used an old unijunction transistor.
Does anybody use a unijunction transistor anymore?
Then why is this teacher asking the student to find the datasheet of an antique 2N2646?

It's still useful as a teaching device for negative resistance circuits.
http://hyperphysics.phy-astr.gsu.edu/hbase/Electronic/unijun.html