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Simple Conversion from Battery to Plug-In

Discussion in 'Power Electronics' started by Bluewaterpig, Mar 2, 2016.

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  1. Bluewaterpig

    Bluewaterpig

    2
    0
    Mar 2, 2016
    Hey guys, new member here. I'm an experienced DIYer from being a guitarist...I've built electronic guitar pedals, modified guitar electronics, etc, and I can solder well enough.

    I have a small appliance that runs on 2 D sized batteries. The inner wiring is very easy to access, please see the attached picture. This is an appliance that you leave on for an extended period of time and I'd love to be able to plug it into the wall instead of having to buy more batteries every week.

    How would I go about converting this so that I can hook it up to an adapter that plugs into a wall socket? Thanks everyone. image.jpg
     
  2. 73's de Edd

    73's de Edd

    3,050
    1,289
    Aug 21, 2015
    .

    Sir Bluewaterpig . . . . . . .

    Looks like you just have yourself a little "Annie Fannie" there.
    Which would just be as simple as initially inserting DC metering in its DC current mode across those switch contacts to see what its running speed current consumption is.
    Then you hop on down to your nearest Thrift store and cull through all of their tangled masses of power adapters and find one of about double or thrice the current capacity
    that you were finding that motor to be using.
    Plop down your "Three Amellican dollahs" to purchase that thang.
    Then you install a power connector on the device to interconnect the power adapter to the fan.
    In assuming that you opted for an EXTREMELY common 5VDC output adapter, then compute the value of series power dropping resistor . . . .using "ohmmatic law" . . . . in order to drop that 5 volt on down to 3 volts under motor load conditions...

    Tha a a a a a a t's it . . . . . unless you happen to have mo' questions.



    73's de Edd


    .
     
  3. sureshot

    sureshot

    234
    13
    Jul 7, 2012
    Hi welcome to the forum. The easiest cheapest way is to mount a low voltage DC chassis socket, say 5.5 mm x 2.5 mm diameters into the housing of this devise. Then use a universal wall adaptor that can meet the voltage and current needs of this device. Other might have different ideas.
     
    hevans1944 likes this.
  4. cjdelphi

    cjdelphi

    1,096
    104
    Oct 26, 2011
    To simplify it... buy a 5v adapter (or a spare usb 120 to 5vdc)

    Then using say an lm317, you could stick out a potentiometer and vary the fan speed from a knob on the side, i suppose a diode could be added to the battery so that when the mains is plugged in, the battery will not drain or charge using non rechargeable cells
     
  5. hevans1944

    hevans1944 Hop - AC8NS

    4,562
    2,135
    Jun 21, 2012
    Or you could connect several (try three or four) 1N400x diodes in series to drop a 5V wall-wart down to the 3V that two D-size cells in series provide. Anything from the 1N4000 series will work: 1N4001, 1N4002, ... up to 1N4007, whatever you happen to find at Radio Shack. The 'Shack sells power jacks and plugs too. Buy a jack that mates with the plug on whatever wall-wart you find (take it with you to the store for a size check). The 'Shack also used to sell "universal" wall-warts with a slide switch to select the output voltage, but you need to check the fan current to make sure whatever wall-wart you get will provide the current needed to run the fan. Another option: use re-chargeable D-cells, but that can be a real PITA, and waaaay expensive since you probably need to keep a pair in reserve on the charger all the time when the fan is in use.
     
  6. Bluewaterpig

    Bluewaterpig

    2
    0
    Mar 2, 2016
    Thanks for the welcoming replies everybody. Those all sound like great ideas. For me, I think the simplest method would be best. You might be giving me a little too much credit, cause I don't really understand any of your directions lol.

    I think what I'd like to do is mount a socket into the side of this and be able to connect a power adapter. If anyone is familiar with the process, would you be willing to give an "idiot simple" explanation of how to connect the socket to the circuit in my picture?
     
  7. 73's de Edd

    73's de Edd

    3,050
    1,289
    Aug 21, 2015
    Sir Bluewaterpig . . . . .




    Why 'soitanly . . . . . . and would ye be needing me to give you the right handed or the left handed instructions ?

    Let's utilize barrel connectors with the female version mounted in your case.
    With that roomy case, its even having enough space to mount a female version that incorporates a crossover switch so that the unit will initially operate just as you have it, using batteries.
    But then . . . . . Plug in the male plug and the batteries are switched out of circuit and the unit then operates exclusively on DC power from a 5 VDC power adapter.

    The marked YELLOW rectangle seems to be the area having the most room to mount the female connector.

    PLUS you still need to measure the current that the device pulls with the motor running . . . .unless there happens to be info molded / marked onto the case near the battery cover plate.


    Female Barrel connector
    https://www.sparkfun.com/products/119

    Male Barrel connector
    https://www.sparkfun.com/products/11476


    Howtodoittoit . . . . . .

    [​IMG]

    Thassssit . . . . . .



    73's de Edd
     
    Last edited by a moderator: Mar 7, 2016
  8. KMoffett

    KMoffett

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    Jan 21, 2009
    sureshot likes this.
  9. 73's de Edd

    73's de Edd

    3,050
    1,289
    Aug 21, 2015
    Sir Bluewaterpig . . . . . . .


    If you opt for the other units mounting . . . .and with Switchcraft not even giving any terminal referencing on their Engineering drawing . . . along with your
    initial qualifying :

    You might be giving me a little too much credit, cause I don't really understand any of your [initial] directions lol

    Would you be willing to give an "idiot simple" explanation of how to connect the socket to the circuit in my picture?

    It seems only logical to now supplement with terminal data on that other unit:

    [​IMG]

    Initially, see if the unit operates just as before, using batteries, and then pull the batteries and plug in the PROPER voltage and amperage Wall Wart power
    supply and see if it works.

    If not, check and /or/ swap your # 2 and #3 terminal connections.


    73's de Edd
     
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