555 Negative Resistance

169

01:40:56

For some reason the 555 output pin has -15Ω resistance. This enables it to power a simple LC negative resistance oscillator that wouldn’t actually work in real life when configured as shown here due to a lack of conservation of energy. Unless it made itself cold in the process (like a normal resistor converts electrical power to heat a negative one converts heat to electricity), but it would then violate a different law of thermodynamics (because it would decrease the entropy of a closed system, assuming it were a closed system).

published 7 years ago

BillyT

7 years ago

If you do bad things to circuit/ICs, don't be surprised if they give funny results.

jason9

7 years ago

But measuring output pin resistance isn’t something bad. I mean, imagine varying the output current a few mA to find the resistance of the output pin. A completely fine thing to do. What is bad is pulling very high currents and realizing voltages are exceeding that of the power supply thereby creating free energy as it can then pump back into the power supply. Don’t you agree?

add comment in editor

EveryCircuit is an easy to use, highly interactive circuit simulator and schematic capture tool. Real-time circuit simulation, interactivity, and dynamic visualization make it a must have application for professionals and academia. EveryCircuit user community has collaboratively created the largest searchable library of circuit designs. EveryCircuit app runs online in popular browsers and on mobile phones and tablets, enabling you to capture design ideas and learn electronics on the go.