Banggood Scope Kit

Discussion in 'The Projects Forum' started by debe, Aug 8, 2015.

  1. debe

    Thread Starter Well-Known Member

    Sep 21, 2010
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    If you go down the Banggood DIY CRO path. Check these pics, there is a fair bit of noise in the amp. But for the price I built 2 of them & reasonably happy to use them. Just alow for the noise. DIY CRO Mains hold.JPG DIY CRO TEST Hold.JPG
     
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  2. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
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    As for building the scope can't you just add some decoupling caps to tone down the noise????
     
  3. debe

    Thread Starter Well-Known Member

    Sep 21, 2010
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    Tried all that & suspect its noise in the amp ic. This is with the input switch in Gnd position. DIY CRO.1.JPG COMP Side.JPG TRACK Side.JPG
     
  4. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    It does not look good at all.

    Is the IC custom made?
     
  5. debe

    Thread Starter Well-Known Member

    Sep 21, 2010
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    The IC is a TL084C (U2) 4x JFET opamp.
     
  6. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    For starters the 074 has lower noise figure (but same GBW).
     
  7. Roderick Young

    Member

    Feb 22, 2015
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    Try powering from a battery if you're not already doing so. Maybe there's noise coming in from a switching power supply.
     
  8. debe

    Thread Starter Well-Known Member

    Sep 21, 2010
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    All testing was battery power. Heres the circuit of the power supply part. Pics of wave forms on Q1 collector & TP25. Both Horz 10us & Vert 1mv/div. Bottom pic is TP25. Have also tried disconnecting the neg 5v power feed, an feeding that with a battery. Still the noise was there. DIY CRO Q1&2, probe position.JPG DIY CRO.circuit, PS.jpg DIY CRO Q1-2. Hor 10uS, Vert 1mV..JPG DIY CRO Tp25 V-- Hor 10uS,Ver 1mV.JPG
     
    Last edited: Aug 9, 2015
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