Electronics – Physics with Keith

Busman’s Holiday

My ten-year-old daughter built a robot by herself. Here’s a ‘proud Dad’ post, with some moaning about the state of primary education.

Internal resistance and delivering the maximum power to a load resistor

I was teaching this on Friday but ran out of time to go through the calculus with my class, so here is a quick(ish) video about why you get the maximum power delivered when you match the load resistance to the internal resistance. Hopefully you find it useful! https://youtu.be/nEY3OsCPZtU If there’s anything you need helpContinueContinue reading “Internal resistance and delivering the maximum power to a load resistor”

More fun with op amps: differentiation

Yes, I finally managed to get an op amp to differentiate an input potential that varies over time. The top trace is the input potential. The bottom trace is the output from the op amp, showing the first derivative of the input. Huzzah! I connected the differentiator circuit to a sinusoidal input potential, and afterContinueContinue reading “More fun with op amps: differentiation”

Fun with Op Amps

One can see the same potential applied to both inputs of the op amp, causing 0V output potential. That made sense. When connecting the inverting input pin to half the potential of the output (using two 10 kΩ fixed resistors as a potential divider), the output potential became 10V. Well, half of 10V is 5V, so that would make the inverting input potential 5V, the same as in the first case, yet the output potential is different.