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Posts posted by ginji

  1. Ante: I think you misunderstood me, i'm not trying to replace a part, rather get one to so i can use it as a precationary thing :)

    MP: First i've heard of NTE, and looking on the distributor list only lists one in Queensland.... a good 600k's away from me at least, with no option of ordering over the net.

    Thanks for your help guys, i may go try and figure out a non-darlington one

  2. C1 upgrades to 4700uF or higher, 10 000uF is suggested i believe

    The rectifer bridge as a single 10A or higher part, this way it can be attached to the side of the case

    I'm changing Q2 from the 2n2219 to a BD139 (you can use a BD137)
    WARNING! the pins on the BD139 is different to the 2n2219

    Feed back resistors (R4/5/6) to metal film type for the lower tolerance

    Other suggestions (not made in this thread, but the other one)
    Replace R2 and R3 with 1/2W resitors
    R7 with 10W resistor
    R1 with 2-3W
    P1 is a many-turns wire-potentiometer (10 turns), and P2 is a "cermet" single-turn

  3. ginji, thanks for the update on the project. I would also be interested in an easy method of building transformers if your dad would not mind sharing. There is a post and an article on this website but it is very difficult. If you could do this, please add as a new post so that the subject is easily found by others.

    it's been a while since he's actually built a transformer (last time was at least 16 years ago if not more) so i think what ever he can actually remember is a bit out of date. The article in articles section explains the process quite well (from my understanding of it) although i can understand that people get confused by i

    the printed circuit board i'm using was made by my uni (yay for my uni) using protel and some CAM stuff (CAM is computer aided manufacturing) so it isn't etched but has the copper round the tracks cut away.
  4. hey all

    I am/mostly have built this power supply, but i've made some changes along the way:

    C1 is now a 4700uF 50V (Maybe change this later...)
    The 3 feedback resisters are metal film (R4/5/6) for the lower tolarence (1% compared to 5%)
    And i'm changing Q2 to a BD139 (if you want to make the circuit 5A then you'll have to change Q2 to one which dissapates more heat, BD139 can also be connected to a heat sink)

    The transformer i'm using is a half-half (half the primary and half the secondary on each side), not sure about the VA, as it is one which my dad made himself a while ago.

    I should be able to get access at uni to a oscilloscope, and test the supply for any problems.

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