How to Amplify 0.1V across an LED terminals to 3V ?

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Discussion Overview

The discussion revolves around the challenge of amplifying a low voltage of 0.1V across LED terminals to a higher voltage, specifically 5V or 6V, using external power supplies and amplifier circuits. Participants explore potential circuit designs and the effectiveness of specific components in achieving this goal.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant describes a circuit they created that measures 0.1V across LED terminals and seeks advice on amplifying this voltage to 6V.
  • Another participant questions the clarity of the problem and suggests that a schematic of the circuit would be helpful.
  • A participant notes that the circuit linked by the original poster appears to be an amplifier designed to operate on a 0.1V supply, which may not be suitable for their needs.
  • One participant mentions that the voltage across the LED is expected to be around 0.1V when no cell phone is transmitting nearby, prompting a suggestion to test the circuit with a cell phone present.
  • Another participant confirms that they measured 0.1V with a multimeter and asks for guidance on how to amplify this voltage.
  • A participant expresses uncertainty about the CA3130's effectiveness at cell phone frequencies and suggests adding an amplifier and detector between the antenna and the op-amp input.
  • One participant requests a specific amplifier circuit diagram to assist with their project.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific solution or circuit design. Multiple competing views and suggestions are presented, indicating that the discussion remains unresolved.

Contextual Notes

Some limitations include the unclear effectiveness of the CA3130 at the relevant frequencies, the need for a suitable amplifier circuit, and the dependency on external factors like cell phone transmission for voltage measurement.

5416339
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I made a circuit in which the LED terminals have a potential difference of 0.1V,So how can i amply this potential difference to 6V using an external power supply.

I found this circuit : http://www.aldinc.com/pdf/amp_27007.0.pdf

I was wondering if this would amply 0.1V or is it something else ? is this is not the answer then please help me.I have to do this somehow :(

Thanking You,
5416339
 
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Is there any circuit available or a circuit diagram perhaps !
 
I'm not clear on the problem... Are you trying to illuminate an LED with a .1v signal? A schematic of the circuit you made would be helpful.

The circuit you posted seems to be an amplifier that runs on a .1v supply (which is a pretty danged low supply voltage), so probably not what you want.
 
here is my circuit : http://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/January2008/CI-09_Jan08.pdf&title=Mobile%20Bug

I want to amplify the PD across the LEd terminals to 5V !How do i do it ?
 
Last edited by a moderator:
It looks to me like the voltage across the LED is supposed to be around 0.1 V when no cell phone is transmitting nearby. Have you tried the circuit with a cell phone transmitting nearby?
 
skeptic2 said:
It looks to me like the voltage across the LED is supposed to be around 0.1 V when no cell phone is transmitting nearby. Have you tried the circuit with a cell phone transmitting nearby?

Yes i tried using a mobile phone and measured the output.

I have measured using a multimeter and your absolutely right i am getting exactly 0.1V so how i amplify it ?

Pleas ehelp :)
 
The CA3130 is not designed for use at cell phone frequencies. I guessed that the input stage was somehow rectifying the cell phone signal and that the DC signal level was what was amplified. However since the front end is using mosfets, I'm not sure how that is being done. If you have a cell phone transmitting nearby and the voltage is not increasing at the output of the opamp, then either a component is defective or the CA3130 is not effective as a detector at cell phone frequencies.

If it were me, I would add an amplifier and detector between the antenna and input to the opamp.
 
Thanks for that suggestion but can you tell me any amplifier circuit for this ?? A circuit diagram maybe !
 

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