Transistors?

Question

ive been into electronics since i was 10, ive been building kits and making my own circuits, the only thing i never understood was transistors and ceramic capacitors, but the transistors more, what is the point in having one? what does it do? and ceramic capacitors, the big brown ones, little discs, why have those instead of the blue ones, electrolytic capacitors

oh, um, i can also make circuits in a digital wokspace program, a simulator, called Crocodile Technology, does anyone know of another program similar to Crocodile Technology?

Answer 1

To expound a bit on the other poster's answer on transistors, they control a larger power source to be proportional to a small input signal. That is to say, they operate something like an old fashioned pantograph did. A small voltage and current is shaping a larger source of voltage and current to comply with the original's waveform. At the simplest level, this is what all transistors do. Some types of transistor circuitry have a lower response time and so can be used to create digital signals.

As to why we don't just use the electrolytic capacitor in everything, it has two faults that the ceramic disc capacitors don't. First, they tend to dry out and loose their capacitance with use. Second, they have the sloppiest tolerances that you'll ever find in an electronic device anywhere. Capacitors in general aren't low tolerance devices, but the electrolytics can be off by as much as 40% - 60% when "new*. Some circuits just won't work with this much slop. If we only used electrolytics, we'd have to fit the values by trial and error in a lot of cases and the circuit might be dead a couple of days later from in circuit value changes by dehydration.

I hope this lets you see the value and general use of these types of components. They are needed in their capabilities and properties, as are most of the components made in modern electronics factories.

Answer 2

Transistors are an active component, as opposed to passive components like resistors, inductors or capacitors. As such, they can be used as the basis for amplifiers and digital logic circuits. Transistors replaced the function of vacuum tubes in electronic circuits; "electronic", by the way, means a circuit that includes active components while an "electric" circuit is purely passive components.

Transistors are used by placing a small control current on the base lead, which causes a much larger current to pass from the collector to the emitter. The C-E voltage is the same as the base voltage, but since the current is much larger (typically about 200 times more than the base current) the power of the signal becomes substantially larger.

Answer 3

Transistors have two main purposes in most electronic devices. They are either used to amplify signals or as a 2 position switch. A huge number of transistors used as switches is the heart of the modern computer. One single transistor can be on or off, which can represent a 1 or 0. A number of transistors can form a binary string such as 10011 or something. This can represent many different things. These 1s and 0s are called bits. Eight bits make up one byte and can represent a decimal number between 0 and 255. Some computers have as many as 2 billion transistors. If you want to better understand the physics of a transistor there are many sites that explain it very well and have good pictures.