Transistors are wired in series and in parallel to create logical operators "AND' and "OR", and inversion "NOT". These are then combined to create "Flip-flops", adders, selectors, which are combined to create memory cells, counters, shift registers, state machines etc. A modern personal computer central processing chip has over a billion transistors wired together to do some very complicated operations at incredible speeds, ie billions of steps per second.
It's called "Buffering" and it's done for several reasons, mainly to isolate internal circuitry from external circuitry. The internal device (a microprocessor?) may be able to output a milliamp on it's outputs, so a switch with an Hfe of 50 can output 50 milliamps. Also, external noise spikes could get onto the internal signals and disrupt them.
the switching capability of a microprocessor is tiny - you need to have the microprocessor control a larger transistor that in turn might control a very large relay to handle much larger currents
or, you'll burn up the microprocessor
The transistor switches in todays are almost out of commercial application. After the massive development in microprocessors and sensors these kind of switches are almost obsolete.
All logic ie all digital electronics, is done with switches, that is why we require them.
The point with electronic logic is that is it a symbolic process, thus, as long as you can accurately detect the two states, it is essentially error free. And as a bonus it is very fast.
Your microprocessor is basically just millions of microscopic transistors - you increase in hardware in order to interface and control larger scaled circuitry and equipment.
Transistor can be constructed as a HIGH SPEED switch where a mechanical switch never able to do it.
why do we require transistor switches ........I read one related forum in that it was written transistor switches can be triggered using electrical signals. TRUE.but if at all u want to off the ckt give zero signal(may be through microproccesor) to the o/p directly why do you want to increase your hardware for that? and when when you want current at o/p give the current directly.anyway we can programme our μp.
so why transistors????????
