How to amplify 5V to 15V using a Base Common Amplifier

Thread Starter

zarabotkalesna

Joined Nov 22, 2015
18
Hi guys! I want to amplify 5V to 15V using a Base Common Amplifier (because it has a high voltage gain), but I'm not succeeding... Cah you please help me? Thanks in advance.
2015-11-22 15.24.52.jpg
 

Thread Starter

zarabotkalesna

Joined Nov 22, 2015
18
I think it's it. Feel free to change anything and give me some suggestions! :)

Please note that the input signal is DC (USB 5V source), not AC. :)
 
Last edited:

bertus

Joined Apr 5, 2008
20,564
Hello,

The circuit is a common base circuit.
The Base is AC grounded by the 1 uF capacitor.
I assume the 5 Volts source on the right is the signal input.
It will NOT amplify the DC voltage as shown.
It also will never reach 15 Volts on the output as the powesupply shown on the lefty is only 5 Volts.

Bertus
 

ScottWang

Joined Aug 23, 2012
6,909
Ib1 = 1.36 mA - 1.34 mA = 0.02mA
I_2.46K = 1.57 mA
I_728Ω = 1.56 mA
Ib2 = 0.01 mA
So why the Ib1(0.02 mA) ≠ Ib2 (0.01 mA)?
 

Alec_t

Joined Sep 17, 2013
11,387
The cap on the emitter of the transistor will block your 5VDC 'input signal'.
You can't get 15V out of that amplifier, since its supply voltage is only 5V.
 

Papabravo

Joined Feb 24, 2006
13,909
I think it's it. Feel free to change anything and give me some suggestions! :)

Please note that the input signal is DC (USB 5V source), not AC. :)
I guess that's because all the grounded base circuits I've worked with had the base connected to GND or Vcc. I thought that blocking the supply on the right didn't make much sense as well.
 

Thread Starter

zarabotkalesna

Joined Nov 22, 2015
18
Hello,

The circuit is a common base circuit.
The Base is AC grounded by the 1 uF capacitor.
I assume the 5 Volts source on the right is the signal input.
It will NOT amplify the DC voltage as shown.
It also will never reach 15 Volts on the output as the powesupply shown on the lefty is only 5 Volts.

Bertus
So, is there a way that I can use my USB port as an input (which is DC), and how much voltage should I apply as Vcc (on the left in my circuit)?
 

bertus

Joined Apr 5, 2008
20,564
Hello,

Then you would need a boost regulator as Alec_t also mentioned.
Keep in mind that the power output will NEVER be more than the input power.
There will ALWAYS be losses in such a circuit.

Bertus
 

bertus

Joined Apr 5, 2008
20,564
Hello,

For what do you want to use the created 15 Volts?
You can amplify 5 volts to 15 volts using an opamp, but you will need a powersupply to feed the opamp.

Bertus
 

bertus

Joined Apr 5, 2008
20,564
Hello,

The power output of USB will be only 300 mA and 1 A when there is a request done.
This will likely be not enough to power the fans.

Bertus
 
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