1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice
Dismiss Notice
This forum does not allow a single user to have more than one username. If anyone wants to change their username contact an admin and it will be done. Multiple accounts belonging to the same member will be deleted without warning.

Unregulated Power Supply Building

Discussion in 'Home Brew' started by Nitmare67, Feb 19, 2009.

  1. Nitmare67

    Nitmare67 Member

    Joined:
    Sep 15, 2008
    Messages:
    27
    Likes Received:
    0
    Does anyone have any plans, schematics or even photos of the inside of an unregulated power supply. I understand they are pretty simple to build and I would like to build a 75-100amp model.

    Thanks in advance


     

  2. dudmuck

    dudmuck Active Member

    Joined:
    May 21, 2007
    Messages:
    482
    Likes Received:
    10
    Yes they are very simple.

    Just take a look at the regulated power supply:
    Power supply : 13.8V 25Amp power supply with LM723+2N6776

    All you need is whats on the far left: The transformer, bridge rectifier, and the big capacitor(s) on the DC side of the rectifier. These components only need to be scaled to the current you expect to run.

    If you cannot find a 100 amp transformer. It is possible to parallel two smaller transformers if they are the exact same model.

    Always put the fusing or circuit breaker on the AC input.
     
  3. linearone

    linearone King of NY

    Joined:
    Apr 2, 2005
    Messages:
    615
    Likes Received:
    7
    power supply design

    first schematic on this page is an unregulated dc power supply

    have fun
     
  4. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    16,547
    Likes Received:
    10,201
    High current unregulated power supplies make me cringe. :eek:
     
  5. Nitmare67

    Nitmare67 Member

    Joined:
    Sep 15, 2008
    Messages:
    27
    Likes Received:
    0
    I am either going to build a 75 - 100 amp for my class C super mega splatter box or purchase a Iota 75amp.

    I have heard alot of great things about the Iota power supplies. They are going for 155 on ebay right now which is a smoking price.
     
  6. C2

    C2 Sr. Member

    Joined:
    Aug 3, 2005
    Messages:
    2,408
    Likes Received:
    73
    The Iotas on ebay that I have seen for cheap are some sort of overstock or other odd lot that do not have factory warranties, unless they are used.

    Maybe the cheapest way to go is to start with an automotive battery charger (100 amp) and put in a big filter cap.
     
  7. Nitmare67

    Nitmare67 Member

    Joined:
    Sep 15, 2008
    Messages:
    27
    Likes Received:
    0
    Right now I run a single battery and a 200 amp fast charger I kick on when I'm on the key alot but the voltage drop is still there.

    I think the 75 amp Iota on ebay would work. Besides the factory warranty is easy to get around.....
     
  8. flamethrower

    flamethrower Diehard CBer

    Joined:
    Oct 16, 2008
    Messages:
    4
    Likes Received:
    0
    Why??? There are only 3 components that can fail in an unregulated supply- The transformer, the rectifier, and the filter caps. Regardless of what fails, the output voltage will drop,, so the equipment connected to the supply will be unaffected. This is NOT the case in a regulated supply:

    The unreg supply I use for my linear idles at 16vdc, and drops to 14.3 vdc under load. The ripple (noise) is held to an acceptable level because my filter cap is 550,000 uf.

    If you "cringe", it simply means that you don't really understand the diffenence between regulated and unregulated supplies.
     
  9. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    16,547
    Likes Received:
    10,201
    Quite the opposite my friend. I made a career out of electronics and spent 22 years in the commercial broadcasting business and it is exactly because of what I DO know that makes me cringe. It has NOTHING to do with simplicity of the circuit and has EVERYTHING to do with the dynamics of a high current unregulated power supply.For a load that has a constant current draw they may be acceptable if the load can withstand the higher no load, or minimum load, voltage as would be the case in a radio where the voltage would be much higher on RX than on TX. Also with a load of varying current demand as in the case of an SSB TX the constant changes in voltage levels can and will mess with the IMD performance of the radio and can cause "FMing" of the signal. In the case of an AM TX flat-topping of the signal can occur much easier than with a well regulated supply. So you see my reasons are based on technical standards of which I have been accustomed too during my career in professional broadcasting and sometimes you just have to know what to look for before you can find anything wrong in the first place.

    BTW I see you could benefit from a spellchecker too. :love: :D
     
  10. WX2MIG

    WX2MIG Still Alive & Well

    Joined:
    Dec 10, 2008
    Messages:
    730
    Likes Received:
    4
    He who lives in a glass house.........:D
     
  11. linearone

    linearone King of NY

    Joined:
    Apr 2, 2005
    Messages:
    615
    Likes Received:
    7

    apparently it was ok for the last century with every tube device ever made, critical critical critical, show a tube amp that has a regulated b+
     
  12. Peddler

    Peddler SWR (sandwich with rum) Expert

    Joined:
    Aug 6, 2001
    Messages:
    2,457
    Likes Received:
    11

    nit⋅pick/ˈnɪtˌpɪk/ Show Spelled Pronunciation [​IMG] [nit-pik] Show IPA Pronunciation [​IMG]

    –verb (used without object) 1.to be excessively concerned with or critical of inconsequential details.
     
  13. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    16,547
    Likes Received:
    10,201
    I said "high current" Tubes generally run on high voltage and low current of an amp or so for typical amateur radio power levels. The big broadcast stuff and some high end amateur gear had choke input power supplies with a smoothing choke whose value was chosen to resonate with the huge filter capacitor to provide better AC ripple rejection. The power supplies also had a swinging choke whose value would change depending on the current through it.They would tend to resist changes in current by changing the voltage drop across them and thus provide a good degree of regulation.Using properly chosen component values one could build a very well regulated high voltage power supply.Keeping in mind that regulation is a percentage of the overall voltage a 100 volt drop in a 3000 volt supply with a current draw of 1 amp is very good. As a matter of fact that is almost exactly what my RCA tx does,from zero amps to full load of slightly over an amp the voltage drops from 3100 to just above 3000 volts. For lower current tube supplies the use of vacuum tube regulators was very common in circuits that depended on voltage stability such as VFO's etc. There were millions of O2A's, OB2's and OC3's in use amond many others.They could also be stacked in series to provide high voltage regulation above what their individual specs were.
     
  14. linearone

    linearone King of NY

    Joined:
    Apr 2, 2005
    Messages:
    615
    Likes Received:
    7
    watts is watts

    quite frankly I sometimes feel more comfortable around high curent lo voltage supplys than high voltage low current

    my 4kv 2 amp supply for my 3000 WILL reach out and touch you
     
  15. linearone

    linearone King of NY

    Joined:
    Apr 2, 2005
    Messages:
    615
    Likes Received:
    7
    watts is watts

    quite frankly I sometimes feel more comfortable around high curent lo voltage supplys than high voltage low current

    my 4kv 2 amp supply for my 3000 WILL reach out and touch you
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!