Increase Current w/ Transistor Config | Common Collector

In summary: only by greatly suppressing the battery current can you achieve a voltage high enough to light up a circuit.
  • #1
SMD1990
49
0
Hello. When I short-circuit my power source/supply, I read 1.5 mA at 120+ VDC. For my purpose, the voltage is sufficient. However, I need to increase the amperage.

I have been playing with amplifying the current using a transistor. However, my breadboarded attempts have all resulted in either little current amplification or a greatly reduced voltage. What am I doing wrong? I thought the common-collector configuration was supposed to increase the amperage while leaving the voltage basically unchanged?

My best results have used a high resistance on the base (10 Megaohms). However, that is of no help when it comes to amplifying the current. And even that results in a reduced voltage of ~95.
 
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  • #2
You need to get a bigger (greater capacity) power source.
 
  • #3
Transistors don't amplify current. They control current. You need to read a little bit more about them, specifically things like saturation
 
  • #4
What kind of power supply do you have?
Some power supplies have foldback current limiting. When you short them, they cut the current way back so it can't harm the power supply or the load. Use a higher resistance load like a light bulb and see if it supplies more current.
How much current do you need?
Jiggy-Ninja is correct.
 
  • #5
I am trying to power a small electroluminescent panel. Its specifications state that it needs somewhere between 5 and 8 mA. At my current 1.5 mA, I can just barely see it beginning to glow. Its light output is very faint.

I have tried various methods for creating the power I need, such as implementing an astable multivibrator with two H-bridges and a CW-stage between them.

Currently, I am trying to use the circuit board out of an old watch that was illuminated by its own EL backlight. Whatever I end up doing, it needs to be as small as possible.

My (potentially incorrect) understanding was that one could amplify current with a transistor. For example, my 100+ voltage source connects to the emitter and collector. A battery (which provides the higher amperage) is connected to the base and emitter. A load at the emitter would receive the 100+ volts and the current supplied by the battery.

If this is incorrect, my understanding of "gain" must be completely out of wack.

My readings show the battery's amperage. However, only by greatly suppressing that current can I see the watch circuit board's voltage. (I have also observed that, if I put low resistance on the watch's AC output, its voltage drops badly. Oddly, a higher resistance shows more voltage.)

Oh, and just so you know: In my current attempts to increase the amperage, I am first full-wave rectifying it to DC. I am not connecting AC to my transistor, and trying to amplify it. It is DC.
 
  • #6
SMD1990 said:
I am trying to power a small electroluminescent panel. Its specifications state that it needs somewhere between 5 and 8 mA. At my current 1.5 mA, I can just barely see it beginning to glow. Its light output is very faint.

I have tried various methods for creating the power I need, such as implementing an astable multivibrator with two H-bridges and a CW-stage between them.

Currently, I am trying to use the circuit board out of an old watch that was illuminated by its own EL backlight. Whatever I end up doing, it needs to be as small as possible.

My (potentially incorrect) understanding was that one could amplify current with a transistor. For example, my 100+ voltage source connects to the emitter and collector. A battery (which provides the higher amperage) is connected to the base and emitter. A load at the emitter would receive the 100+ volts and the current supplied by the battery.

If this is incorrect, my understanding of "gain" must be completely out of wack.

My readings show the battery's amperage. However, only by greatly suppressing that current can I see the watch circuit board's voltage. (I have also observed that, if I put low resistance on the watch's AC output, its voltage drops badly. Oddly, a higher resistance shows more voltage.)

Oh, and just so you know: In my current attempts to increase the amperage, I am first full-wave rectifying it to DC. I am not connecting AC to my transistor, and trying to amplify it. It is DC.
What's the battery voltage? If it's less than your high voltage source (which it seems to be, or you wouldn't be having this issue) it won't work.

You need a power supply that can put out more amps. I don't think there's an easier way around it.
 
  • #7
SMD1990 said:
My (potentially incorrect) understanding was that one could amplify current with a transistor.

Yes, when a small amount of current in the base is able to control a larger amount in the collector then we often refer to this current amplification. It can't however somehow magically generate more current than is supplied by the power supply as the transistor itself contains no energy source. Did you ever learn about conservation of energy or have you just temporarily forgotten about it?
 

1. How does a common collector transistor configuration increase current?

In a common collector configuration, the input signal is applied to the base of the transistor while the output is taken from the collector. This allows for a high input impedance and a low output impedance, resulting in an increase in current.

2. What is the role of the emitter resistor in a common collector configuration?

The emitter resistor, also known as the load resistor, helps to stabilize the output current and voltage by providing a path for the current to flow through. It also helps to prevent the transistor from overheating.

3. How does the current gain differ in a common collector configuration compared to other transistor configurations?

In a common collector configuration, the current gain is typically higher than in other configurations. This is because the input current is amplified by both the base and collector currents, resulting in a larger output current.

4. Can a common collector configuration be used for both AC and DC signals?

Yes, a common collector configuration can be used for both AC and DC signals. It is commonly used in AC amplifiers as it provides high voltage gain, while also being able to amplify DC signals with minimal distortion.

5. What are some common applications of a common collector transistor configuration?

Common collector configurations are often used in audio amplifiers, voltage regulators, and level shifters. They are also commonly used in sensor circuits to amplify small signals before they are further processed.

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