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Need help choosing a substitute regulator component

Discussion in 'General Electronics Discussion' started by Y2KEDDIE, Jun 14, 2018.

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  1. Y2KEDDIE

    Y2KEDDIE

    259
    15
    Sep 23, 2012
    I have a Conar power supply, Model 320. It uses only a few compnents: full wave bridge, transformer, a few capacitors, and a 4 terminal IC (UA 78HG), T05. Package. Pos. Voltage regulator.

    I’m having a difficult time finding the UA 78HG. ( four terminal, variable, pos voltage regulator)

    I would like to duplicate this power supply circuit because the design simplicity.

    What is available in IC’s that I use in place of the UA 78 HG?

    Bigger current capacity > 5 A is ok.but I want it to be variable 5 to 14 VDC. And use the same/or close design (few components).

    Also what transformer secondary voltage should I use (min and max)? I can measure the existing supply transformer I have, but I am courious what range would work, as I have several transformers in my ‘junk box’.

    Your suggestions please.
    Thank you
     
  2. kellys_eye

    kellys_eye

    4,281
    1,144
    Jun 25, 2010
    It is unlikely that the transformer in use for the 78HG will have a high enough output to deliver 14V from a variable regulator.

    Had it been able to then a simple LM317 with a pass transistor to increase the load capacity would be a simple solution however you can now get high-amperage versions of the LM317 going under the designation LT1083 and kits containing all parts, pcb etc are only a few $'s on eBay.

    You will require a different transformer though but if you have a spare laptop PSU with around 19V output then you could use that to feed the module.

    Add a cheap ($2) digital volts/amp meter and you'd have a useful variable PSU.
     
  3. Y2KEDDIE

    Y2KEDDIE

    259
    15
    Sep 23, 2012
    I looked at the kits on e-bay for the LT1083 which contain only a populated PCs but no transformer:around $10.

    Then I found this complete switching supply for around $15:

    My plan is to use this supply to power a automobile car sound system from 110vac mains.
    I’m hoping the switching does not cause noise in the audio .

    I never used a switching supply in this application, only linear supplies.

    Padarsey 110/220V to DC12V 10A 120W Switch Power Supply Driver Power Transformer for CCTV camera Security System LED Strip Light(12V 10A)
     
  4. davenn

    davenn Moderator

    13,381
    1,784
    Sep 5, 2009
    without some decent filtering, switching noise may be a problem

    so if it being used to supply a car stereo, do you really need a variable supply ?
     
  5. kellys_eye

    kellys_eye

    4,281
    1,144
    Jun 25, 2010
    In-line filtering (choke) on a SMPS will help (I run one in my workshop) but I'd still prefer a linear solution! On a cost basis it's certainly worth trying the SMPS you refer to.
     
  6. Y2KEDDIE

    Y2KEDDIE

    259
    15
    Sep 23, 2012
    No, I really don't need a variable supply for this application. I've been using the variable Conar supply in my shop, and it works well, and it it is simple. For that matter, it does go to 12VDC, I wanted 14VDC as the top end because 13.8V would be optimun..I guess 12vdc is enough with regulation.

    The plan is to operate a car stereo off of 110VAC mains. I want a dedicated supply and not tie up my bench supply.

    Those little kits with the LT1083 probably are the best solution, even though I need to have a transformer. The filtering capacitor pictured looks a little small.

    I ordered the SMPS through Amazon Prime to experiment.

    A separate issue:
    I would like to buy and try the LT1083 supply, or similar.. I never yet have bought anything off of E-bay . I never used PayPal either. I see the "buy it now" button. Is it safe to use one's personal credit card?
     
  7. kellys_eye

    kellys_eye

    4,281
    1,144
    Jun 25, 2010
    Buyers get a lot of protection through the use of Paypal - using a credit card via their site is perfectly safe.
     
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