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

  1. Aug 25, 2010 #1
    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,
  2. jcsd
  3. Aug 25, 2010 #2
    Is there any circuit available or a circuit diagram perhaps !
  4. Aug 25, 2010 #3
    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.
  5. Aug 26, 2010 #4
    here is my circuit : http://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/January2008/CI-09_Jan08.pdf&title=Mobile%20Bug [Broken]

    I want to amplify the PD across the LEd terminals to 5V !!How do i do it ?
    Last edited by a moderator: May 4, 2017
  6. Aug 26, 2010 #5
    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?
  7. Aug 26, 2010 #6
    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 :)
  8. Aug 26, 2010 #7
    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.
  9. Aug 26, 2010 #8
    Thanks for that suggestion but can you tell me any amplifier circuit for this ?? A circuit diagram maybe !
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