creating AA Lava lamp into USB powered lava lamp

[The End of A Heartache]

Ok, i had this cool looking tri color AA battery powered lava lamp lying around. I love this lamp cause it was a wifie gift before we got married

I had it packed away cause i think i got tired of it eating my AA like it was junk food. I had resently found it when i was dong a clean up "Cause im such a packrat" (wifie quote)

i didnt want to throw it away cause it is awesome, tri color LED/ oil lamp. But i hate hate hate hate! buying giant packs of battery and throwing the spent once away after it just ate it up after 8 hour of use. Its just bad for the enviorment wasting so much battery. AND yes i have bought rechargeable kinds but again it eats it up every 8 hours of use and charging takes 8 to 12 hours..running back and forth from charger to lamp to keep it going is to much hassle.

Ive deside to go ahead and mod the lamp to run on USB power so i can also adapt it to solar power

issue being i face is i know the lamp needs 3 AA to run..which each battery is about 1.2 or 1.5volts ... and USB pumps out 5 volts ..mathmaticly (1.2*3=3.6volts needed) so i need to drop the amount of voltage to a safe level of 3.6 maybe less to reduce blown outs...but i dont know how many milliamps the USB port oushes off

so i want to make sure i dont kill the mini 555 chip on the board i need to calculate the right amount of current.

then i need to figure out what kind of resistor to buy and solder it to the switch

Does anyone know how do i do that? i know so much but dont have training in anything further DX

[802Chives]

USB is 5V and is capable of sourcing 100mA... I would guess that probably you would be fine running that device right off from the 5v usb power because most cmos circuitry will work up to 6V. (most common 555 chips are cmos)

If you were really concerned and wanted to make sure ur device stays alive you could try using a LM317 adjustable regulator between your USB and set the voltage for 3.6-4V

If you know how to measure current you could take a measurment using batteries to make sure the 100mA is not exceeded.  If you wanted to estimate usually each LED uses 5-20mA.

Good Luck.  I can step you throught the LM317 if your interested, but I am fairly sure your device would work fine from USB without modification. 

Alternatively you could buy a wall wart power supply that is around 3.3-4.5V and use that as well.

[The End of A Heartache]

Ty 802Chives and yes i would like some help in using LM317

 i did some googling and found this page out on LM317 http://www.westfloridacomponents.com/T064PD/LM317LZ+LM317+LZ+Adj+Voltage+Regulators+TO92.html

i think i might be able to find this at radioshack, but how am i suppost to regulate the amount of resistance?

Its best to wait to get some help and more inforamtion on this by 802chives

[802Chives]

ok so i was looking for good referance material for the LM317 and it would seem that you will need 1.5V-2.0V overhead for this linear regulator... this means that you will have to have an input voltage that is 1.5V-2.0V more then the output voltage, so this regulator is not the best choice.

What you need is a LDO or Low DropOut regulator which I wasnt able to find at Radioshacks website.

Another way to drop the voltage it to use a beefy diode like this
http://www.radioshack.com/product/index.jsp?productId=2062579&tab=techSpecs

With that you hook up the Anode (side with no line) to the +V from the USB, and the Cathode (side with line) to the +V of your Lamp, and hook up ur grounds like normal.  Wiring this diode in series with your circuit will give you a Forward voltage drop of 1.2V accross the diode according to the spec sheet:
http://www.vishay.com/docs/88516/1n5400.pdf

that is a simple way to make your 5V into 3.8V

Note: diode may get a little warm.

[The End of A Heartache]

oh so i would need to have a high voltage basicly 5v + 2v? for that specific LM317..

 ohh wow that is one beefydiode..i might be able to find it off of one of old boards from my  "packrat board box" i have XD (wifie calls it that go figure)

ok so i basicly connect this diode (the side without the silver strip) to the + line of the usb and from(the side of the diode thats solid black)  to the board.

question i have cause i never picked up on the whole parrellel and series thing. but i think i might have the hang or idea of what is a series.

seres is Connectiong end to end like this (( +-[]-+-[]-)) ??

oh and i would then need to just have 1 of this diode to do a proper drop of 5v to 3.6v?

[802Chives]

you are going to be putting the diode in line with your positive lead, the negative leads will just hook up together as normal.

The USB positive hooks up to the side of the diode with no line

The Lava lamp positive hooks up to the side of the diode with the line

Series connection is when you hook things up in a line so positive to negative to positive to negative

Parrallel is when you hook things up side by side so positive to positive and negative to negative

hope that makes sense, if not google is better at explaining then I 

[The End of A Heartache]

Ok im ganna go and buy the diode today so i can start rebuilding.

Oh ok so i got it right then that actually made more sence then what a friend keeps telling me of what a parellel is lol thanks for the help 802Chives 

ok i went to radioshack to find a 3amp diode..so far none of them carries any diode..not even in their drows of components... one of the guy looked back and said they only carry 1amp diode...but i didnt get it cause i didnt know what kind i needed.. there were three that he showed me and three that i found on the neT:

1N4003 Micro 1-Amp Diode
http://www.radioshack.com/product/index.jsp?productId=2036269

1N4005 Micro 1-Amp Diode
http://www.radioshack.com/product/index.jsp?productId=2049728

1N4004 Micro 1-Amp Rectifier Diode
http://www.radioshack.com/product/index.jsp?productId=2036270

I really dont have the full background on components other then resistor and LED.

which one should i buy for my tri color lava lamp mod?

or

does it even matter?

[802Chives]

woops didnt see you updated ur post...

ok 1Amp diode will be fine, but be aware that it may get real warm to the touch.  Since you are only really able to pull 100mA from your USB you will be safe with 1A diode. 

All of the diodes you listed will work just fine.

[The End of A Heartache]

lol its ok

actually since my last post i went ahead and bought those 3amp diode from this online electronic component store http://www.alliedelec.com/

i order 3 3amp diode on friday and just got them this morning(monday) by usps

i got the one's listed from radio shack 1n5404

they added a discription: 3A; 1.2(MAX); 500 UA (typ); 200A; 400v

[802Chives]

cool, let us know how it works out.

[The End of A Heartache]

came out perfict  it does what it should very perfictly thank you 802Chives for the great help