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Xenobius

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Posts posted by Xenobius

  2. Convert 0-30V 3A PSU to 5A or more

    in Electronic Projects Design/Ideas

    Posted

    Hello everyone I need to build this transformer quickly so I couldn't wait for help on this forum so I asked the R&D Engineer were I work and he modified it for me. Now since I recived a lot f info from this forum I will share the modification and even HELP anyone who needs more info.

    To make this circuit take up to 5Amps you need to:

    1. A transformer with 24VAC 5Amps
    2. Change R7 to 0.27Ohms 9W (or else 2x 0.15Ohms 5W In series)
    3. Change C1 to 6800uf (or else 4700uF in Parallel with 1000uF)
    4. Change D1, D2, D3, D4 from 1N5402 to 6Amps Rectifying Diodes

    Also for safety I am going to make 2x 2N3055 in Parallel. (follow diagram attached for help in connecting them.)

    post-2368-14279141631299_thumb.jpg

  5. Led display Digital Voltmeter question

    in Projects Q/A

    Posted


    Hi all,
    Where can I get the "EXACT" PCB pattern layout for this project? I tried to used the layout in this post but everytime I print it out it's always oversized.. :(
    I set my printer to 1:1 but to no avail..
    please help.. :'(



    Try to use a drawing software like photo shop or paint shop pro to resize the pcb and before you print always check the size from print preview so you would know if it's over sized or not!

  7. High current fixed voltage

    in Electronic Projects Design/Ideas

    Posted

    Hello all

    I would like some help in building a fixed voltage.

    I have 12vac 12A which I would like to make them 12VDC Fixed
    and 5vac 5A which would like to make them 5VDC Fixed.

    I know I have to pass them firstly from a bridge ... I bought one which can go up to 25A so now you can say that I have 12V Pulsating DC and 5V Pulsating DC. What can I do to make the 12v / 5v DC and make use of the 12A and 5A because a 7812 and 7805 only handles 1A.

    ty

  8. Drilling IC holes in a PCB

    in Electronic Projects Design/Ideas

    Posted

    Well first of all you must use a SMALL driller to it is easier to handle and ofcoarse a small drill.

    The normal sizes are 0.8mm for normal components, 0.6mm for vias (jumpers) and 1mm for large componnets like voltage regulators, large rectifying diodes etc..

    IF You use a 0.8mm drill and a small driller, if you aim right the drill will automatically find the hole and drill it ... (it bend a little) because the copper forming the pad will act as a guide.

  10. Convert 0-30V 3A PSU to 5A or more

    in Electronic Projects Design/Ideas

    Posted


    I have built this PSU. It looks nice but I am disappointed with its (or my) performance.
    The maximum current (Imax) and voltage (Vmax) outputs vary widely and proportionally to the resistance of the load (Rload).
    For example:

    Rload (Ohms) Imax (Amps)

    4 >4.0
    5 3.5
    15 1.6
    32 0.8
    75 0.36
    etc. etc.

    The Vmax of 30V is gradually approached with increasing Rload but never reached, except under no-load conditions.
    As it can be seen the relationship between Rload and Imax (and Vmax) is not linear but parabolic.

    I am using a good quality VARIAC rated at 7.5A and set at 24V.
    I have replaced the 4 rectifier diodes with an 8A bridge.
    C1 is 4700 microF.
    Overheating is not a problem (big heatsink with fan).
    Apart for an "above board" jumper between pin out #10 and the junction of R4 and R6 - done to avoid the long, winding trace to ground - I have made no other modifications.

    Has anyone had a similar experience?
    Do you have any idea what the problem might be and how to fix it.
    Thank you,
    (a rather frustrated) Mastrila.

    ???



    I have a torodial transformer with 2 outputs of 12.6v so I put them in series to get 25.2v and the result is that it gives me 34.8vdc (if you want to see the picture go to

    http://www.electronics-lab.com/forum/index.php?board=2;action=display;threadid=128;start=75

  11. Convert 0-30V 3A PSU to 5A or more

    in Electronic Projects Design/Ideas

    Posted


    I'm going to build the circuit as soon as possible, but i'm very busy bcause of my exams. I think , the diodes will be replaced by 6A types, because i have them at home, and the input capacitor will be a bit bigger, 4700uF or so because i have some in stock :)

    As soon , as it will be complete, i'll do some measurements.


    Yes it will work mate because I didn't find a 3300uF Capacitor and used a 4700uF instead. and also the Diodes I used are 6A ( to be safe ) and it works

  12. Convert 0-30V 3A PSU to 5A or more

    in Electronic Projects Design/Ideas

    Posted

    Hello first of all I have built the PSU (0-30V 3A PSU) and it's GREAT but I built it becasue the PSU I was building last year which is mentioned below had a faulty circuit acording to my school techer and my work mate.

    Last year I wanted to built a little PIGGY (PIGGY = HUGE). SO I had a Transformer CUSTOMLY made for me.

    The Transformer is 600VA
    Input :
    240VAC

    Outputs :
    1. 30V 5A
    2. 30V 5A
    3. 12V 12A
    4. 5V 5A

    I wish someone could help me if possible.

    I wish to make a Circuits which can handle the 30V 5A regulation including the current limiting so I can built 2 of it for the 2 outputs.

    and I wish someone could tell me HOW to make a 12v 12A into a FIXED 12VDC with 12A (or maybe 10A) and also 5V 5A fixed

    THANKS a lot for your assistance

  14. 0-30 Vdc Stabilized Power Supply

    in Projects Q/A

    Posted

    Hehe thanks buddy for the compliments :D and sorry for the 50w resistor :p because I don't have one.

    Here is another picture of it so even the people who are going to build it will have an idea of the layout :) (sorry for the dirt on the table but I was just drilling a PCB lol)

    post-2368-14279141629988_thumb.jpg

  16. 0-30 Vdc Stabilized Power Supply

    in Projects Q/A

    Posted

    Ok People I fixed it :D

    So take this as a tip:
    IF IT varies the voltage from 23v to 35v ONLY, you got the Emitter and Collector of the 2N3055 Mixed UP lol..

    Cheers!! when I arrive home I will post some pictures if the administrator lets me (until I arrive home I hope the administrator will already have posted if I can post pics or not)

    10x

  19. 0-30 Vdc Stabilized Power Supply

    in Projects Q/A

    Posted

    Hello All I have built this power supply but I got a problem. As soon as I switch it on, the volt meter reads 23.5v and then I try to vary the Volt Pot, it goes up to 35v! In other words, my PSU is only variing from 23.5v to 35v !! I have changed the op amps twice and even tried the TL071 (which is better acording to a friend of mine who read the datasheets) Could anyone help me PLEASE?

    thanks a lot

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