# 2N2222A current buffer circuit

Discussion in 'General Electronics Discussion' started by ahmedg, Jun 26, 2018.

1. ### ahmedg

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Jun 25, 2018
i need to amplify an IC output signal current using 2N2222A need help with the connections??

Last edited: Jun 26, 2018
2. ### HarryA

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Jan 22, 2017
If you search on the following and click on the link for Hunter college you get a lesson on using the 2n2222 that maybe helpful:
"15. Transistor Amplifier Design and Measurement"
I can not pass the url for some reason as it links to a pdf file.

edit: well I guess it does work here

3. ### BobK

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1,686
Jan 5, 2010
You need to tell us what you are trying to do. Signals are not usually currents (though they might be). Are you talking about linear amplification (duplicating a waveform) or are you just talking about using a digital signal to turn something on or off?

Bob

4. ### ahmedg

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Jun 25, 2018
using a digital signal on and off but the IC output signal won't operate the mosfet so i had to amplify it using a bjt so i need to know kan i use a 12v 1 amp as Vcc and the value of the Rc

5. ### ahmedg

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Jun 25, 2018
can i use this voltage follower circuit as a current amplifier because i don't have any problems with the voltage?

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6. ### BobK

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Jan 5, 2010
MOSFETs are voltage operated and do not need any appreciable current, so you still are not describing the problem correctly.

What is the voltage of the signal when ON and when OFF?

Most likely, a logic level MOSFET is what you need. These can be turned on with voltages in the 3-5V range.

Bob

7. ### ahmedg

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Jun 25, 2018
i knew it but the electronics store guy put this current idea into my head i'm using IRF1010E which has gate threshold voltage at 2v and the output of the IC ranges between 3.5-3.8 but i measured the mosfet output and it was 0 v using a 12v 1amp adaptor as a Vcc on the Source pin of the mosfet. thanks for your help

8. ### BobK

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Jan 5, 2010
Show us a circuit.

2V is the minimum theshold voltage. You need to go by the max, which is 4V. And at the threshold voltage, it only passes 250uA.

And the source should be connected to ground, no Vcc.

Bob

9. ### ahmedg

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Jun 25, 2018
so this is the timer circuit and i have the output to the gate of the mosfet and its Vcc is 12v,1amp and i should get 12 v output to operate a 12v solenoid valve (there is no led or 330 ohm at the output did it for testing the output of the IC)

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10. ### ahmedg

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Jun 25, 2018
how to i connect the source to ground while i need 12v (using the mosfet as a switch)

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11. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
You place the load between Vcc (or Vdd in this case) and the drain.

12. ### ahmedg

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Jun 25, 2018
ok so source is ground
gate has the input voltage
and load between drain and vcc
right?!!!

13. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
That is typically how it's done.

You might add a resistor (say 100k) between gate and source to ensure that the MOSFET remains in the off state when power is not applied.

14. ### ahmedg

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Jun 25, 2018
thanks steve it worked with no resistances the deadline is in two hrs