dual output power supply regen

Discussion in 'Homebrew and Kit Projects' started by KB2WVO, Nov 26, 2018.

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  1. KB2WVO

    KB2WVO Ham Member QRZ Page

    ok i built the regen in image below.. tho i did not have the audio chip. i used a 386 setup..
    issue our....both on own breadboards.
    1... if i feed both regen and 386 from a cheapo VarDC supply. one of them over the pond ones. squeeeellls
    2... if i feed 386 off a LM317 down to 6v and regen with a diff supply set to 5v. tho they both feed off the same 12vdc. its ok
    3...if i feed regen and 386 from the LM317 the regen wont work.

    i was thinking 1 volt cant be that much harder on the 310s. but for some reason i can not control the feed back off the neg side of the power supply.. i think that is what is the issue ?? ground loop ? i dont know..

    the audio feed to the 386 is rite after the 1uf. the 386 is setup off data sheet basic 20Gain setup. to be sure keeping basic for trouble shooting.. but piff i can not figure out the power issue. lol
     

    Attached Files:

  2. N7EKU

    N7EKU Ham Member QRZ Page

    Hi,

    I suspect that you are getting feedback through the positive line when it is being used to power both the regen circuit and the audio amplifier. That is why it works OK with the separate power supplies. The original design uses separate regulators -- probably for just this reason.

    You could try and provide some isolation using a 10 ohm resistor in series with the power lead followed by a capacitor to ground. Also, a 10uF capacitor from the lm386 pin 7 to ground might help too.

    It looks like the design was done by Ray Charles Ring:

    https://circuitsalad.com/2012/09/30/a-high-performance-regenerative-radio/

    You could try reading through his blog on it, and contacting him there (he seems pretty responsive).

    73,


    Mark.
     
    Last edited: Nov 27, 2018
    KB2WVO likes this.

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