Spintronics Community Forum

Negative Resistance

Circuits
#1

An example of a Negative Resistance device:

Increase the resistance value of the 20Ω resistor upwards to 1000Ω. The transistor will turn itself on, allowing a higher current to flow. Decrease the resistance again, and the transistor turns off.

The circuit can be made to self oscillate:

Twist the capacitor to start oscillations. When the capacitor is uncharged, it’s effective resistance is low, so the transistor will not turn, but the capacitor will be charged from the battery. When the capacitor charges up, the resistance increases, causing the transistor to turn on, which discharges the capacitor and starts the cycle again.

#2

Adding a second transistor. Twist the capacitor again to start the cycle.

#3

In the single transistor case, I need to add a inductor and change to a 200Ω for it to oscillate in the real world.

#4

I made the two transistor case also work in the real world. Twist either the capacitor or the inductor to start. 500Ω might be slightly heavy in the real world, 300Ω works best for me. Thanks for the inspiration.