Difference between mechanical switch and a transistor switch?

In summary: Vac lamp for 4 hours after sunset every day. He plugs it into the wall socket and has a photodetector on it which he uses to turn on the light. Very convenient.
  • #1
user111_23
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Doesn't a transistor switch need a mechanical switch? Otherwise, how does the transistor switch turn on and off? Does the switch have a "mind" of it's own?
 
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  • #2
A transistor switch, e.g., an npn transistor, can be triggered by a sound, light (photodetector), an electrical signal, or a radio signal (e.g., garage door opener).
Bob S
 
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  • #3
Bob S said:
A transistor switch, e.g., an npn transistor, can be triggered by a sound, light (photodetector), an electrical signal, or a radio signal (e.g., garage door opener).
Bob S

Thanks for the reply. And if it isn't too much, how would an electrical signal alone switch a transistor?
 
  • #4
I believe the answer to your last question can be readily found by considering the NMOS or PMOS transistor.
 
  • #5
╔(σ_σ)╝ said:
I believe the answer to your last question can be readily found by considering the NMOS or PMOS transistor.
What did you have in mind?

Bipolar junction transistors draw very little collector current if they have no base current and draw a lot more current if they do have a base current.
So, to make them draw collector current you just need to produce a base current from some event.
If the event is very short (in time) then there are ways of producing a much longer time to turn a switch on or off for a longer time.

If they do draw a collector current, this can be used to do something useful. You might turn on a LED, for example.
The transistor has to be used in certain ways to keep it safe and so it works at all, so it is not as easy to use as a mechanical switch but it has many advantages.
It can be triggered by electrical signals.
It can switch much faster than a mechanical switch.
It is silent.
It never wears out.

A good example.. Suppose you want to turn on a light when the sun goes down.
You have a light detector driving a transistor switch which turns on the light. It isn't as simple as that, but you get the idea.
How would you do that with a mechanical switch?
 
  • #6
vk6kro said:
A good example.. Suppose you want to turn on a light when the sun goes down.
You have a light detector driving a transistor switch which turns on the light. It isn't as simple as that, but you get the idea.
How would you do that with a mechanical switch?
I've got a little black box I am our sunroom, about 5 or 6 cm on a side. It plugs into the wall socket. It has a photodetector on it, and a knob labeled OFF ON 1 Hr 2Hr 4Hr 8Hr.
I use it to turn on a 120 Vac lamp for 4 hours after sunset every day.
Very convenient.
Bob S
 

FAQ: Difference between mechanical switch and a transistor switch?

1. What is the main difference between a mechanical switch and a transistor switch?

The main difference between a mechanical switch and a transistor switch is the way they control the flow of electricity. A mechanical switch physically opens and closes a circuit, while a transistor switch uses a small electrical signal to control a larger flow of electricity.

2. Which one is more durable, a mechanical switch or a transistor switch?

In terms of durability, a transistor switch is typically more reliable than a mechanical switch. This is because mechanical switches are prone to wear and tear from constant physical movement, while transistor switches have no moving parts and therefore have a longer lifespan.

3. How do the sizes of mechanical switches and transistor switches compare?

Mechanical switches are typically larger in size compared to transistor switches. This is because mechanical switches require physical components such as levers, buttons, and springs, while transistor switches are made up of tiny semiconductor materials that can be easily miniaturized.

4. Can a mechanical switch and a transistor switch be used interchangeably?

No, mechanical switches and transistor switches serve different purposes and cannot be used interchangeably. Mechanical switches are better suited for simple on/off operations, while transistor switches are used for more complex switching tasks that require precise control over the flow of electricity.

5. Which type of switch is more commonly used in modern electronic devices?

In modern electronic devices, transistor switches are more commonly used. This is because they are smaller, more efficient, and can be easily integrated into complex electronic circuits. Mechanical switches are still used in certain applications, such as in household appliances and industrial equipment.

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