Hello everyone.

I want to use a Darlington Transistor to amplify current to drive one CPU fan.
I am limited with supplying sources of 5V.
CPU fan voltage, power and current: 12V, 2,16W & 180mA.

Please see picture below and tell me why I cannot reach 180mA?
Thanks in advance.

 

Hello everyone.

I want to use a Darlington Transistor to amplify current to drive one CPU fan.
I am limited with supplying sources of 5V.
CPU fan voltage, power and current: 12V, 2,16W & 180mA.

Please see picture below and tell me why I cannot reach 180mA?
Thanks in advance.

View attachment 95149

Probably because you're only giving a 12V fan 5V.

 

Because Mr.Ohm said that current is directly proportional to the voltage and is inversely proportional to the resistance.

 

Probably because you're only giving a 12V fan 5V.

I knew that, but what's then the purpose of amplifying?

 

You have two choices:
1. Increase Voltage
2. Reduce motor windings

 

I knew that, but what's then the purpose of amplifying?

View attachment 95150

[Dumbfounded]...................I'll let someone with more patience explain it to you.

 

I'm afraid I'm not that someone, but I suggest a search for 'amplifier' will give you plenty of explanatory material.

 

Then Sorry for asking... )

I'm pretty new to these concepts, and I'm here to learn, but if you don't want to help me that's not a problem, I'm good with that too.
But remember, even you, as well, didn't known anything until you learnt it.

Have a nice day )

 

Then Sorry for asking... )

I'm pretty new to these concepts, and I'm here to learn, but if you don't want to help me that's not a problem, I'm good with that too.
But remember, even you, as well, didn't known anything until you learnt it.

Have a nice day )

You'd get a little more enthusiasm if you did at least *SOME* research off your own back.

 

Option 3, replace said 12V fan for a 5 V one....fixed

 

Thanks

 

Here is a pretty basic article about amplifiers.

http://www.allaboutcircuits.com/textbook/semiconductors/chpt-1/amplifiers/

 

Option 3, replace said 12V fan for a 5 V one....fixed

5V fans are pretty gutless - I've been known to run 12V ones up to 18V when mounted next to a light bulb for chopping up flies etc.

 

Here is a pretty basic article about amplifiers.

http://www.allaboutcircuits.com/textbook/semiconductors/chpt-1/amplifiers/

Thanks, I'll read it )

 

The purpose of amplifying is to using a small current or voltage to control the bigger current or higher voltage.

When you can control the current and voltage then you can adjust the speed of motor and the brightness of led or lamp, when you can control the current and voltage then you can control the load through computer, even through the smart phone to adjust the brightness of led or lamp, remote car speed control, etc...

 

The purpose of amplifying is to using a small current or voltage to control the bigger current or higher voltage.

When you can control the current and voltage then you can adjust the speed of motor and the brightness of led or lamp, when you can control the current and voltage then you can control the load through computer, even through the smart phone to adjust the brightness of led or lamp, remote car speed control, etc...

Understand, Thanks

 

Because your base current is such a large percentage of the collector current, your circuit is acting as a saturated switch rather than as a linear amplifier. Also, both collector currents are wrong. The direction of collector current in the left transistor is backwards. Since its current does not go through the right transistor, that transistor's current is wrong. Both collector currents go through the right transistor emitter. If you add reference designators to each component, this stuff is a whole lot easier to talk about.

The circle with 898 next to it is not a standard schematic diagram symbol, so no one here can say what its electrical characteristics are. It is not clear if 61.5 mA is the limit of the current available from the 5 V source, or the current drawn by the magic circle, because both are labeled the same. If the magic circle has an equivalent resistance of 66.7 ohms, then the circuit is behaving.

The reason you got such poor responses is because your question does not indicate any understanding of the most basic aspects of DC circuits, and without that there is no language for communication.

ak

 

a

Because your base current is such a large percentage of the collector current, your circuit is acting as a saturated switch rather than as a linear amplifier. Also, both collector currents are wrong. The direction of collector current in the left transistor is backwards. Since its current does not go through the right transistor, that transistor's current is wrong. Both collector currents go through the right transistor emitter. If you add reference designators to each component, this stuff is a whole lot easier to talk about.

The circle with 898 next to it is not a standard schematic diagram symbol, so no one here can say what its electrical characteristics are. It is not clear if 61.5 mA is the limit of the current available from the 5 V source, or the current drawn by the magic circle, because both are labeled the same. If the magic circle has an equivalent resistance of 66.7 ohms, then the circuit is behaving.

The reason you got such poor responses is because your question does not indicate any understanding of the most basic aspects of DC circuits, and without that there is no language for communication.

ak

Thanks for your reply.
I have a basic understanding of DC circuits, but now I'm trying to learn new concepts, and I know those are banal to you...
Next time I'll do a better research before I post anything.
Thanks to all )

 

Option 3, replace said 12V fan for a 5 V one....fixed

It would probably do the TS some good to search on audio amplifier clipping and read through the articles - they pretty much cover why an active device on a 5V supply cant put 12V into the load.

The options are; use a 5V fan as you say - or use a flyback converter to boost the voltage.

 

I understand, thank you )