difference between General switch and Transistor as a switch

Thread Starter


Joined May 6, 2012
here is a question that is being ask in general discussion in friends that what is the difference between normal switch e.g a simple button , and Transistor as a switch.

anyone can explain this question.



Joined Apr 11, 2010
A "general" switch is manually controlled; a transistor switch is electrically controlled. A general switch is a single component; a transistor switch requires supporting components (resistors, etc...). A general switch can have multiple positions (throws) and circuits (poles), but these have to be designed using transistor switches, using multiple transistors and supporting components.
I chuckled at sirch2's explanation.
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Joined Sep 9, 2010
Another difference - A normal switch has only two positions although it may produce electrical bounce when switching from one state to the other. A transistor is perfectly capable of being at any position in between the two endpoint states, ie. it can function as something other than a switch.


Joined Aug 23, 2012
In the electronics area, the big different is that the normal switch just using for manual control, it needs the human to press it, but the transistor switch can be using in the automatic control, you just give it a high or low voltage level, then the transistor switch will work for you, and the high or low voltage level can be output from the control circuit or a timer, or a comparator, this is what the normal switch can't do.


Joined Mar 14, 2008
A mechanical switch provides essentially infinite OFF resistance and very low ON resistance. It also provides complete electrical isolation between the input control and output, such as a with a mechanical relay.

A transistor exhibits a finite leakage current when OFF and an ON resistance that can vary from a few tenths of an ohm to a few tens of milliohms depending upon its current rating and type of transistor (BJT or MOSFET). It also requires a common ground between the control input and the output.


Joined Nov 18, 2012
Lets not forget that size matters. An everyday spst switch would not be practical on a small circuit board controlling mA. A transistor would not be practical for switching lights or motors due to higher current. So one size does not fit all


Joined Sep 9, 2010
Another difference: Most mechanical switches latch. No action is needed once the switch is thrown. A transistor requires continuous control.


Joined Jun 8, 2013
Hello :)
Another difference:

A manual pushbutton, for example, is a passive device. That is, it requires no electrical power to operate it. In addition, when the switch is in its "open" state, there is an "air gap" between the terminals of the switch.

A transistor, on the other hand, is an active device and requires power to operate it. There is no "open" state between the terminals, only a minimal conduction state.