I am currently learning electronic on my own. And I have a question about the circuit below.
Given: 2N6027 is a programmable unijunction transistors. (I'm not sure if that is the right schematic for it)
Question: The objective here is to make the LED oscillates on and off. I have tried all of the three circuits below, but only Circuit 1 works. Why circuit 2 does not work? I believe the resistors R2 and R3 in circuit 1 are connected in series anyway right?
Why does the PUT's gate have to be in between R2 and R3?
simulate this circuit – Schematic created using CircuitLab
Below are the pictures of the Circuit 1
http://examples.oreilly.com/9780596153755-files/mkel_02/mkel_02_098.pdf http://examples.oreilly.com/9780596153755-files/mkel_02/mkel_02_103.pdf