added power supply

Discussion in 'General Electronics Chat' started by kenjc, Dec 12, 2008.

  1. kenjc

    Thread Starter New Member

    Dec 12, 2008
    hi.. i'm adding a plug-in power supply (120v ac to 6v dc) to a baby swing that now runs on 4 D cells. I have the parts I need to do this, but i'm unsure as to the actual wiring it up. I've seen radios that use batteries and also have the AC plug-in option hard wired in (no jack to interupt the battery connection, and I want to know how it's wired up.
    I wonder about having the power supply (6v 1800ma) connected directly to the battery connections. I'd think the batteries (non rechargeable) would somehow short out the power supply. If that's correct, I'll just remove the batteries, but again, my radio works with either. Someone please gimme a clue? thanks
  2. PRS

    Well-Known Member

    Aug 24, 2008
    Your idea sounds good to me. Try it. If the batteries get hot remove them -- you
    re drawing too much current. I may be wrong, but if those batteries were rechargable then they'd be charged every time you used your AC-DC supply. The question is will your new supply get hot? Just give it a quick try and feel everything for heat. Then try it a little longer until you're satisfied it doesn't get to hot in the steady state.
  3. PRS

    Well-Known Member

    Aug 24, 2008
    After a little thought, here's a case you have to watch out for: if the batteries are really low or worse they will draw current from your new supply and overheat it. Best thing is to add a double-pole, double-throw switch to make the supply either by battery or by AC adapter.
  4. SgtWookie


    Jul 17, 2007
    Bad idea!
    You must add a diode to ensure that the batteries won't be charged by the adapter, otherwise the batteries may explode, particularly if they are primary batteries (like alkaline, lithium, etc.) Having things explode in the immediate vicinity of an infant is a very bad thing!

    I completely understand the motivation to save money, however safety is of paramount concern in this case.

    My best immediate suggestion is that you get two sets of rechargeable batteries and a commercially available charger specifically made for charging those batteries. This will not void your warranty or cause you to have to make any modifications whatsoever to the swing.

    Otherwise, if anything bad should happen to the infant while in the swing, litigation-happy prosecuting attourneys would latch onto your modificatons like the hounds of hell.