Electronics is Fun

Imagine we have two transistors lying on the work bench on a lazy Sunday afternoon and we'd like to do something exciting out of them.  How much can we do out of them? One would be a crude Current Source . You may recall that two transistors assumed to be reasonably matched will produce the same current given the same voltage across base and emitter (VBE). Notice that Q1's base and collector are tied to make the base voltage equal. The programmed current is the supply, 5V, minus ~0.6V, divided by the reference resistor (5V-0.6)/RF..  The reference resistor can be made variable, so that the output current varies. The load can be LED, so that makes it dimmable by adjusting the reference resistor. The current source is certainly not precision, but can be useful in many practical applications like the example shown. Current Source Circuit Another would be a waveform generator, an  Astable Multivibrator . It relies on the capacitor discharging and discharging and t...

In today's age of Internet of Things, machine learning, artificial intelligence, cloud computing, and so on, one might wonder what place the operational amplifier has in the current state of affairs in technology. Is it still really relevant that it's worth continuing to learn them in school or by one's own effort? My answer is yes, and this takes us back to the early beginnings of why the operational amplifier was invented in the first place. To those who are familiar with its history, we recall that it was Harold Black's idea in the early 20th century of negative feedback that the operational amplifier takes it root back to its very beginning. The first Integrated Circuit (IC) op-amp didn't come to us until the mid-1960, as the first operational amplifiers were in the form of vacuum tubes and discrete components. In the early days of amplifiers in the beginning of 1900's, these devices are notoriously non-linear and distorts a lot in telecommunication...