I have a npn 2n2222 TO92 30V maximum transistor. I connected the + of a 12 V DC power source to a led, the led 2nd input to the collector, the base is unplugged and the emitter is connected to the minus of the source. I sketched this in a free app online(sorry if it looks like a 5 year old kid drawing). In the left is the circuit using conventional symbols, in th right is the same thing drawn with real life situation:

My question is why is the led lit, when the base is unplugged? It shouldnt allow electricity to flow from collector to emitter if the base unplugged, correct? It looks like it allows and that completes the circuit and lit the led.

 

Welcome to AAC!

My first suggestion would be to double check the pinout of your transistor. There are two styles of 2N2222.

What is the actual part number of your transistor?

 

It is 2n2222 TO92 from a brand called Arduino Clone, is it the same with Arduino? Anyway this it it:

It looks like it is a 331 after 2n2222
It has on the top a flat side with the writing and a round side. I assumed that I place it with the flat side to me and the first is Emitter, 2nd Base and 3rd Collector, thats what I saw online.

 

Bad year to be buying semiconductors | All About Circuits

 

331 is too much of a coincident and could indicate a fake.

Test the leads with a DMM in diode mode. If you don’t know how to do that just ask for directions.

 

Test the leads with a DMM in diode mode.

I have no idea what that means. I am a very beginner. The idea is that I am from a small country in Europe and I bought from an online market which native to my country. It is like the ebay of my country.

 

Welcome to AAC!

2N2222 are in a TO-18 metal can. PN2222 come in TO-92:

 

Do you have any kind of test meter, analog or digital meter?

 

I have something that looks like a screwdriver and lights if it detects electricity, without needing to complete the circuit it can detects just the + of DC or just the - of DC

 

I have a volt meter.

What is the make and model of the voltmeter? Can you post a photograph?
Does the voltmeter have a resistance measurement mode or a diode measurement mode?

 

A transistor has three legs. Number them as 1-2-3.

Use a meter in resistance mode or diode mode.
Measure the resistance in both directions, for example,
(1F) Red lead to 1, black lead to 2
(1R) Red lead to 2, black lead to 1

Do this for 6 possible combinations and directions.

1-2, 2-1
2-3, 3-2
1-3, 3-1

 

I can't photograph it because I am on a PC now. This is the image of it from the website I bought it:

It is a very cheap one 10$. The product code is: V20D-Green

 

If you reversed the collector and emitter terminals, you broke down the base-emitter junction and the current gain of any affected resistors will be damaged.

 

Thanks for the photo.
No, that will not work. If you have no alternative we can make it do what we want to do.

If you ever plan on pursuing electronics as a hobby or career then having a digital multimeter DMM is sound investment.
If you have limited funds, even a low cost analog meter might be better than nothing.

Let us know how you would like to proceed.

 

This is the image of it from the website I bought it:
It is a very cheap one 10$.

Do you mean US$10. You can buy those things on Ali Express for around US$1.

You can make a diode checker using 2 AA batteries and a flashlight bulb.

 

I will buy the tools I need. I think this test will work: I risked a transistors and my DC adapter, but i found this:
I will note 1 2 3 the transistor legs:
I tried + to 1 - to 2 I got a short circuit
i tried - to 1 + to 2 I got a short circuit
I tried + to 2 - to 3 I got a short circuit
I tried - to 2 + to 3 I got a short circuit
I tried+ to 1 - to 3 I got a short circuit
I tried - to 1 + to 3 i got a short circuit
There is no possible combination that the transistor stops the current to flow

 

I will buy the tools I need. I think this test will work: I risked a transistors and my DC adapter, but i found this:
I will note 1 2 3 the transistor legs:
I tried + to 1 - to 2 I got a short circuit
i tried - to 1 + to 2 I got a short circuit
I tried + to 2 - to 3 I got a short circuit
I tried - to 2 + to 3 I got a short circuit
I tried+ to 1 - to 3 I got a short circuit
I tried - to 1 + to 3 i got a short circuit
There is no possible combination that the transistor stops the current to flow

I don't know what you did but I am going to bet that you killed the transistor.

Do not use your 12VDC adapter (or any adapter or battery) to test your transistor. You are going to kill the transistor every time.
Do you have any resistors at hand?
If so, what values do you have? We are looking anything in the 1k to 100kΩ range.
Do you have a plain red LED? (not the 12V LED that you are experimenting with).

 

I think this test will work: I risked a transistors and my DC adapter

What is the voltage and current rating for your adapter? What do you mean by you measured shorts? I suspect that you destroyed every transistor you checked.

This is a picture of the continuity tester that can be used to test transistor junctions and many LEDs and diodes:

A tube that holds 2 AA batteries, a bulb that contacts one end of the batteries and a clip on the other.

 

All of these configuration gave me sparks in the transistors

 

We want to be able to create a circuit similar to this:









You must use a resistor. This is not an option. The value of the resistor is important. Without the resistor you will destroy the LED and your transistor.
We will select the resistance value depending on the voltage source you have available.