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Simple circuit works with BC547A.butBC547, but not with 2N3904

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Simple Circuit Workscircuit works with BC547A, but.but not with 2N3904

FollowingI am following a very simple schematic which is a NOT gate with a push button as input and the. The output is used to drive the base of a second transistor that turns on aan LED:   

NOT Gate Schematic

This circuit works perfectly fine when two BC547A transistors are used:
If the push button is NOT pressed, the LED is on, otherwise off - like it is expected with a NOT gate.

But ifIf I switch the two transistors againstfor 2N3904, it does not work anymore and the LED stays always off.

Both, the BC547A and 2N3904, are simple NPN general purpose transistors and up. Up until now I was under the impression that they could be exchanged with each other pretty much always. Apparently, I was wrong, but would really like to understand what causes the difference in this very simple circuit to make one of them work and the other one not.

To be as precise as possible, that'shere are the data sheetsdatasheets of the two transistors used during testing:

Thanks in advance for any tip on this matter!

P. S.: It's clear that the NOT gate could drive the LED directly, this is just a test setup to use the output of the gate to drive another transistor.

Simple Circuit Works with BC547A, but not with 2N3904

Following very simple schematic which is a NOT gate with a push button as input and the output is used to drive the base of a second transistor that turns on a LED:  NOT Gate Schematic

This circuit works perfectly fine when two BC547A transistors are used:
If the push button is NOT pressed, the LED is on, otherwise off - like it is expected with a NOT gate.

But if I switch the two transistors against 2N3904, it does not work anymore and the LED stays always off.

Both, the BC547A and 2N3904, are simple NPN general purpose transistors and up until now I was under the impression that they could be exchanged with each other pretty much always. Apparently, I was wrong, but would really like to understand what causes the difference in this very simple circuit to make one of them work and the other one not.

To be as precise as possible, that's the data sheets of the two transistors used during testing:

Thanks in advance for any tip on this matter!

P. S.: It's clear that the NOT gate could drive the LED directly, this is just a test setup to use the output of the gate to drive another transistor.

Simple circuit works with BC547A.but not with 2N3904

I am following a very simple schematic which is a NOT gate with a push button as input. The output is used to drive the base of a second transistor that turns on an LED: 

NOT Gate Schematic

This circuit works perfectly fine when two BC547A transistors are used:
If the push button is NOT pressed, the LED is on, otherwise off - like it is expected with a NOT gate.

If I switch the two transistors for 2N3904, it does not work anymore and the LED stays always off.

Both the BC547A and 2N3904 are simple NPN general purpose transistors. Up until now I was under the impression that they could be exchanged with each other pretty much always. Apparently, I was wrong, but would really like to understand what causes the difference in this very simple circuit to make one of them work and the other one not.

To be as precise as possible, here are the datasheets of the two transistors used during testing:

It's clear that the NOT gate could drive the LED directly, this is just a test setup to use the output of the gate to drive another transistor.

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ab-tools
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Simple Circuit Works with BC547A, but not with 2N3904

Following very simple schematic which is a NOT gate with a push button as input and the output is used to drive the base of a second transistor that turns on a LED: NOT Gate Schematic

This circuit works perfectly fine when two BC547A transistors are used:
If the push button is NOT pressed, the LED is on, otherwise off - like it is expected with a NOT gate.

But if I switch the two transistors against 2N3904, it does not work anymore and the LED stays always off.

Both, the BC547A and 2N3904, are simple NPN general purpose transistors and up until now I was under the impression that they could be exchanged with each other pretty much always. Apparently, I was wrong, but would really like to understand what causes the difference in this very simple circuit to make one of them work and the other one not.

To be as precise as possible, that's the data sheets of the two transistors used during testing:

Thanks in advance for any tip on this matter!

P. S.: It's clear that the NOT gate could drive the LED directly, this is just a test setup to use the output of the gate to drive another transistor.