Alternative to PP9 Battery

Discussion in 'The Projects Forum' started by Swati Okhade, Jul 2, 2015.

  1. Swati Okhade

    Thread Starter New Member

    Jun 27, 2015
    9
    0
    I am working with a project that requires a PP9 Battery. However I am unable to get the same. Even Wikipedia says that such batteries are not found much nowadays. Can anyone suggest me an alternative to this battery?
     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,542
    1,251
    What is the project, how much current does it need, and how long must it run on one battery charge?

    ak
     
  3. Swati Okhade

    Thread Starter New Member

    Jun 27, 2015
    9
    0
    It is the same electronic dice circuit...
     
  4. Swati Okhade

    Thread Starter New Member

    Jun 27, 2015
    9
    0
    How to find how much current it needs?
     
  5. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    Just use an ordinary PP3. If you need longer run time, use a 6-cell AAA or AA holder.
     
  6. Swati Okhade

    Thread Starter New Member

    Jun 27, 2015
    9
    0
    That would be great. But then what is the difference between these 2 batteries? Why does the circuit need pp9 battery?
     
  7. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    The PP9 is larger and capable of sourcing more current. It was designed to provide the grid voltage for vacuum tube radios. There's nothing about your circuit that requires it. The theoretical maximum current draw for your circuit is less than 100mA.
     
    Swati Okhade likes this.
  8. Swati Okhade

    Thread Starter New Member

    Jun 27, 2015
    9
    0
    Thanks a lot.
    Please also tell me how to find the current requirement for a given circuit?
     
  9. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    It's not simple. I made some estimates based on what components were there and the resistor on the common cathode connection of the display. You can get some good numbers from the data sheets for the components but breadboarding and measuring is the surest method.

    That appears to be an old design. A newer one might use lower power components.
     
    Last edited: Jul 3, 2015
  10. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    pp9 are still available , try ebay or amazon
     
  11. Swati Okhade

    Thread Starter New Member

    Jun 27, 2015
    9
    0
    Yeah.. But they are hell lot costly.. Moreover if its only use is to run the circuit for some extra tym.. Then I think I will prefer pp3 instead. No offence :)
     
  12. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    A common approach is to use up the battery, then when its spent carefully unpick the steel jacket and discard the innards.

    Some people build a mains "battery eliminator" small enough to fit inside, Another approach is to fill it up with cylindrical Ni-Mh cells.

    A popular trick with the old valve era HT batteries, was to build a SMPSU boost converter to run off a lower voltage pack. The vintage radio sites have some nice pictures of these built into emptied out battery jackets.

    Its best to make sure the battery you buy has a metal jacket - but you can still pack the cardboard ones with rechargeable cells.
     
Loading...