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kollin

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Posts posted by kollin

  1. Okay sir, I will add an external power supply for the meter.

    1. I really can't get a hold of these new op amps. I searched online, and found uA741CP Op amps, is it a good sub?

    2. Also, I was thinking of connecting the center tap like the attached image, since it's easier to get a hold of a center tap transformer in our area. Would this work? 

    3. Did anything change from the original schematic? I am trying to redesign the board to accommodate the updated parts list. 

    Thanks. 

    CT.JPG

  2. Thanks for the reply audioguru! 

    Yes, I will supply them with a separate supply. I added a 7812 regulator after the capacitor. I reversed engineered the PCB from banggood because I'm too lazy to make my own. 

    I will change the parts according to your parts list, mr audioguru. I cannot find the MC34071 in my place, can I use the LM741 instead?

    And I think they don't have 24-0/28-0 single transformers here, so how would I go about editing the rectifier circuit into accommodating a center tap trafo? (14-0-14 or 12-0-12)

    The 30V  doesn't really matter much to me, though. 

    Thank you so much.

  3. Hi. I think I read somewhere that I could use a voltmeter as a makeshift ammeter for this project. 

    Can I use this type of voltmeter?

    http://www.ebay.com/itm/2pcs-Mini-DC-0-100V-Red-LED-3-Digital-Display-Voltage-Voltmeter-Panel-Motor-/381374425176?hash=item58cbafe858:g:dtcAAOSwo8hTmvxX

    How will I hook it up to the unit? 

     

    I haven't built the power supply yet. I am still waiting for the parts. 

    Also, I saw the original circuit in a kit form that is sold on banggood.com (link) Most of the reviews are good. The transistors were modified, and the two zeners, if I remember correctly.

    Q2 = 2SD882 (2N2219 in the original)

    Q4 = 2SD1047 (2N3055 in the original)

    D7, D8 = 5V1 Zener (5V6 in the original)

    Any insights about this? 

     

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