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Belgium
Asked — Edited

Dropping 3.3V To 3.0V

I managed to destroy one Robosapien board by putting 6v where it shouldn't go:(

I'm going to use the 3.3v supply on the ez-b to power my other Robosapien, but now I'm a bit nervous about blowing it.

What resistor should I use to drop the voltage from 3.3v to 3.0v? I read up on Ohm's law, but it seems to depend on how many amps are being pulled. Is that right?

I need to run two cables from the 3.3v supply on the ez-b to the two 3.0v inputs on the Robosapien board.

Any thoughts?

p.s. electronics novice, don't underestimate how little I know:)

#6  
Only PROBLEM with resistor you will find is that you need a big wattage type ,because of the current draw of robosapien plus if using everything else it draws a lot of current, about 2 to 3 amps or more

There is high current motors on the feet plus other motors used in the arms and hands ,plus cpu on the main board and sensors.

PLUS second part you will see is that the main pcb on the robosapien needs 6 volts

Can find the link on the teardown of the robosapien models is shows it needs 6 volts on main board for it to work.

PLUS not very stable,i am electronic engineer

Voltage divider is great for analog circuits,becuase it only uses very low current.
#8  
WITH 6 volt battery dont need to drop it to 3 volts,may be you dont understand about robosapiens to much ,i have many of them and repair them they use two 3 volt batteries in series if you trace the wires you will see negative going to positive to get 6 volts total

What you will get is 12 volts to robosapien board and robot and it will smoke it,now there is a easy fix that will work
i did it on mine tie the 2 red wire together and the 2 black wires together to get 6 volts at double the current.

IF its hard i can try to explain it better.
#9  
The board will power the EZB ok,only you dont need since the EZB has its own regulator to drop 6 volts to 3.3 volts for EZB
United Kingdom
#10  
@dalex Honestly, I have no idea. Battery life is still acceptable on my 5000mAh LiPo however I've never checked for length of life with and without the monitor attached. Even if it did shorten the life it's a small price to pay for protection against under voltage LiPo cells :).
#11  
DALEX i agree with RICH (YES) it doesnt shorten the life of LIPO only thing that shorten the life is charging and discharging (using it in a robot or any other design) cycles
Belgium
#12  
@robotmaker I smoked it after only attaching one 6v battery, thinking exactly along the lines you suggest: just put one 6v battery in each foot and put them in parallel rather than series.

Maybe I got the polarity wrong? Though the circuit should have some kind of protection, since people put batteries in the wrong way all the time. So I don't understand what I did to break it:)

On my robots there is a brown plug with a purple and a red wire (plus two white ?sensor? wires). There is also a white plug with a black and a purple wire (plus two green ?sensor? wires). From what you say, I should be able to plug the two 6v battery packs, in parallel, into one of these plugs. Is that right?
Belgium
#13  
p.s. I see now that the two purple ones are joined on the board, leaving only the red and black wires with 6v across them!
#14  
That what i said it would give you 12 volts reason you smoke the board.
Should look at getting a simple dc meter ,its easy to use even if non engineer or tech

I need to look at my robosapien model i have it depends mostly on the color wires you are using ,you always check the positive on 3 volt battery and trace where is goes and same with the ground.
#15  
You need for parallel batteries together for it to work ,reds together and blacks together
some designs use different colors.

I think i made a mod to the board or cut the wires and add them together
Belgium
#16  
The battery is rated at 6v, but it says 6.4 on my voltmeter. That wouldn't be enough to smoke it would it?

Sorry to labor the point, but I want to be sure I'm not going to smoke my other Robosapien.
Netherlands
#17  
It won't. The voltage is probably a bit higher because there's no load on it.
#18  
THANKS NEIK that is correct ,mostly when you check a battery it needs a load to get the correct voltage out.
Belgium
#19  
Thanks guys, learning a lot.
#20  
Couple of things DALEX ,wednesday can check my robosapien to see how i wired it.

Second can sell you the main board for robosapien robot,i only have one ,since i just used a few other parts to restore one i boughtand dont need the board was going to sell on ebay
Belgium
#21  
Using your advice, I have my other Robosapien running with 6v rechargeable batteries in each foot!
#22  
OK great glad it works,i have 9 robosapiens and looking to get femisapien at about $400

CHECK OUT MY ROBORAD V2 showcase ,also bought a special EEG mind control headset plus free software to control robosapien models and other wowwee line of robots and my rovio robot
Belgium
#23  
Is it an emotiv headset? That's what I do for my day-job, analysis of brain signals. Last month I've been working on analyzing data from the emotiv headset in real-time, using some new methods, and I thought "hmm, I wonder if down the track these methods could be used to control a robot?" That's how I started looking around for the latest robot platforms.

p.s. Robosapiens can be picked up from across the channel for 5 to 10 pounds. Already have a replacement coming.
#24  
yes its emotiv headset and i have a MINDWAVE headset too. will look for the free software to control the wowwee line.

ALSO in college since i am electronic engineer i made a EEG design using a scope
#25  
Robodance pro and i forgot its now $25 for .

BUT can post it as a zip file.