Batteries to plugs

[jaege]

This may be an odd question or it may be one that was already answered, but.... I personally hate battery operated props, because of the need to change batteries. I assume that it is possible to hack an item to change its battery power source to a receptacle source. I know that I could find a general conversion from the batteries to a walwart, my question is: How exact do I have to be? If I am hacking a device that uses 3 double "A"s then I am using roughly 4.5 volts dc. Can I use a walwart that provides 5 volts, or 3? How about 6? I dont want ot experiment and blow up my little prop. has anyone ever invented this "wheel", so I dont have to reinvent it?

[4nntt]

I don't think you're going to get any generic answers to this, as it really depends on what your prop is, what it does, and how it was built.

Here's my stab at some general considerations though (take my advice with a grain of salt though, as I'm far from an electronics expert).

If it's just a motor, then the voltage is probably not that critical at all. Bulb lights shouldn't be that critical either, but LEDs might be.

If it's a circuit board, it is probably a bit more crucial. If the circuit board is regulated you might have some wiggle room, but not too much because you don't want to overheat the voltage regulator either. My understanding is that most circuit boards that are strictly battery operated are not well regulated if at all, since it's not really necessary with batteries.

For anything with a circuit board in it, I would try to match it up as close as you can, error on the low side, and use wall warts that are fully regulated so there is as little variation and noise as possible.

[Just Whisper]

How funny Jaege, I just asked this exact same question on another forum. LOL Good question. I will follow this post. Thanks.

[jaege]

It may be common sense, but thats good advice, 4NNTT. I really dont know how the device runs yet as its in storage in my attic, and I have yet to take it apart. There are actually two items. One is a pumpkin with a light and one of those blower/flame devices inside it. I cannot imagine there is a circuit board on that. The other is a raven with a motion sensor that caws and has LED eyes light up when activated, that may have a circuit board.

[bradbaum]

The way to do it is to count the batteries, each battery cell equals 1.5 Volts.

number of batteries times 1.5V = voltage of the wall wart that you will need.

The exception here is 9V batteries they equal 9 Volts.

make sure that you buy a regulated wall wart to be safe.

Solder the wires to the springs in the battery compartment (you can not use batteries from now on) You can usually see the springs that have the internal wires hooked to them. The spring end is negative and the tab end is positive.

You should buy a multimeter, if you don't have one - you will need it to double check the wall wart wiring (With the volt meter setting) when you check the voltage, it should be positive - if it is not reverse the test leads. Now that the voltage is positive, the wire with the red test lead is positive, and the wire with the black test lead is negative.

Also you can use the ohm meter to sort out what terminals in the battery box are shorted and which ones lead to the internal circuits.

[theedwin]

Well, I have a little experience in this.

It all depends upon the prop that you use. As 4nntt said, if it is a circuit board, the voltage better be the same. (most if not all are run off some sort of circuit board, therefore you better use the correct voltage.) Basically, if it uses any type of sensor, it will run off a circuit board. Having said that, there are ways to hook it up to a wall wart.

First off, find the right wall wart. If it runs off batteries, it needs to be DC. (Direct Current) Also, make sure you have enough amperage. Too much amperage is better than not enough amperage. The unit (prop) will only use as much amperage as it needs. This is completely different than Volts. The volts are what is important.

I suggest you go to Radio Shak (or an equivalent store) and purchase a variable output wall wart. (more amps are better remember, but also more expensive) The reason you want to get one of these (variable output) is so that you could use this for other things when and if you need to. Otherwise you could just purchase the correct voltage (make sure it is correct!)

Here is a little demo video I made for a WONDERFUL little gal that I know.... I hooked up the wall wart to some random 3 battery 4.5 volt toy that I had lying around.

toy animatronics :: VID00261.flv video by theedwin - Photobucket@@AMEPARAM@@http://vid443.photobucket.com/player.swf?file=http://vid443.photobucket.com/albums/qq158/theedwin/toy%20animatronics/VID00261.flv@@AMEPARAM@@vid443@@AMEPARAM@@443@@AME PARAM@@qq158/theedwin/toy%20animatronics/VID00261

Notice that I use the Alligator clips. If you would like, you could always solder the wires (test it first to make sure it works) to the prop. If your prop moves around alot (like say for example a dog that is going to walk around) be sure to secure the wires to the prop so that they won't fall off/be ripped off as the prop moves around (tape or hot glue work)

I am not an expert, but I have done this with a few props of mine and have had great success.

Good Luck!

Edwin

[pshort]

Measure the voltage on the batteries when the device stops working. This should be a lot lower than the rated battery voltage. For a device that uses 9V batteries you may find that the dropout voltage is 8V or even lower. You should be able to use that number (whatever it turns out to be) as a lowest voltage on the power supply, and for the highest voltage I would use the nominal battery voltage (the one on the label) plus maybe 5%.

And, to repeat what others have said, make sure that you're usiing a regulated power supply.

[theedwin]

I think the 9volt battery thing was thrown in there by someone else. The question was about 3 batteries, not a 9 volt battery.

The person who asked the question is not ready for a 9 volt battery question. Who is?

In fact, I have yet to run across a battery operated prop that runs on 9 volts. Correct me if I am wrong please.

Edwin

[jaege]

Nice demo theedwin, which proves my theory. It is just a matter of replacing the battery voltage (and amperage) with the appropriate walwart. I also would like to bypass the motion sensor. Another thread was saying that would be difficult due to the way the sensor worked, but it is just a switch, correct? All I should have to do is use a few leads to bypass that portion of the board?

[hpropman]

You have two options one is to get a regulated 5 volt wall wart for any device that uses 3 Batteries (AA, AAA, C or D) they run them at 4.5 volts because adding the forth battery with push to voltage to 6 volts which could damage the board. If you do not have a 5 volt regulated wall wart then you can add a regulator circuit yourself you can use one of these:

http://world-educational-services.info/cart/index.php?main_page=product_info&cPath=12&products_id=74

Just solder to a circuit board add the wall wart and the wires to the prop and your done. You can also make the circuit yourself it is a very simple circuit. here is how to make it:

http://www.tkk.fi/Misc/Electronics/circuits/psu_5v.html

or this:

http://www.mybitbox.com/articles/standalone-voltage-regulator/

Please ask me if you have any questions