About Femisapien's power subsystem

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Shai Alyt NEMO
Shai Alyt NEMO's picture
About Femisapien's power subsystem

To GWJax:

As I understand, you have already completed the Femi's total disassembly. Did you investigated her power subsystem?

Does all 6 AA's simply connected in series (9v), or there are 4 AA's (6v) for motors and 2 AA's (3v) for brain? Personally, I think it's the second case, but I'm not sure.

I'm thinking of adding an external power jack and if needed, two integral voltage regulators for 3v and 6v somewhere in her boots (I hope, her motors consumed not more then 1A in maximum, so 7806 will do for 6v). So, if not wandering, she can be able to run on mains, thus reducing my battery expenses. And if a power jack is pulled out, she must switch to a battery power.

But I'm slightly afraid of accidentally burning her out...

GWJax
GWJax's picture

Shai, Yes you are correct the Left leg provides 6v for her movements and the right leg provides ~3V for the brain aka MCU. This is the reason why the left leg holds the cutoff fuse. The LM7806 will work just fine and as always make sure you filter the voltage out using caps. Really the only way she will draw more than 1amp is if the motors bind up but this is why you need that fuse installed to prevent damage to the circuit board.

I think that your hack would be a great idea if you don't mind her being tethered but a better solution is to make her rechargeable using the same idea you have.

Jax

Shai Alyt NEMO
Shai Alyt NEMO's picture

Grrr! Yell Read THIS, please:

-----------------------------------------8<---------------------------------------------

BTW, if you wish to shorten my nick, better call me Nemo, because "Shai
Alyt" is a title or rank in Minbari race battle (star)fleet (in Babylon-5 universe)
roughly equivalent to earth's "ship captain" or "high commander" thus
Shai Alyt Nemo is just Captain Nemo (remember Jules Verne's classic
sci-fi book ;). 

-----------------------------------------8<---------------------------------------------

Sorry, no offense, I understand that not anyone here is a Babylon-5 fan. Wink

And let's go on.

I am glad, that my guess was right in general (but I used to think, that upper 2 AA's in her boots are for brain and lower 4 - for motors). Anyway, just one left leg (as you say) cannot provide 6v, it's just 3x1.5=4.5v.  What do you thik?

Also, it's good that her motors consume not more then 1A. So, I can use a 6v voltage regulator (like 7806) for motors and 3.3v one (like SGS-Thomson LF33CV). The ground is common, as I understand?

And making her (detacheable) wired to mains is OK for me as I still dreaming of this:

http://www.robocommunity.com/forum/thread/15302/To-wire-the-wireless-Fem...

and feel now some new wave of inspiration on this project.

So, your help may be useful!

 

 

GWJax
GWJax's picture

LOL Hey what can I say Captain Nemo!!! I was under the influence from the drugs the doctor gave me for one of my procedures I had done that day.. But still SORRY ;)

OK now that I have a clear mind lets start over again.
On the left leg wire connector the Blue and Green wire = ~4.5V and the from there staying with the Ground "Black wire" and the Blue is ~3V and so is the Black and Grey ~3V.
on the Right leg Power the Blue and Orange ~3v and Green and Red is ~1.5V

The motors operate at ~1.5V Max yet not all motors are running at the same time. Each motor runs with a PWM and the MCU is always watching the VR's when they are moving.
After reading over my notes the Red and Green wire from the right leg helps out with the motor movements while also providing a regulated 3.3V to the MCU "Brain".

So thus giving the Femi the operating power of only ~6V for the complete system. So your now asking why 6V when the Femi has 5 motors "5 x 1.5V = 7.5V" this is because as you may already know all motors do NOT run at the same time via the PWM commands the MCU provides to each motor in steps as they are needed. Each motor has a rough resistance of 15 ohms and this is for all standard WowWee motors with exceptions in the Alive series like the Elvis and Chimp. So knowing these 2 units V=1.5v and R=15ohms the current for each motor at it's max 0.1 Amps. "Ohms Law = V=IR"

I'll add to this tonight since I have to go to work now.

Jax

Shai Alyt NEMO
Shai Alyt NEMO's picture

GWJax said:
LOL Hey what can I say Captain Nemo!!!

Sort of Wink

GWJax said: 
On the left leg wire connector the Blue and Green wire = ~4.5V and the
from there staying with the Ground "Black wire" and the Blue is ~3V and
so is the Black and Grey ~3V.
on the Right leg Power the Blue and Orange ~3v and Green and Red is
~1.5V
The motors operate at ~1.5V Max yet not all motors are running at the
same time. Each motor runs with a PWM and the MCU is always watching
the VR's when they are moving. After reading over my notes the Red and
Green wire from the right leg helps out with the motor movements while
also providing a regulated 3.3V to the MCU "Brain".
So thus giving the Femi the operating power of only ~6V for the
complete system. So your now asking why 6V when the Femi has 5 motors
"5 x 1.5V = 7.5V" this is because as you may already know all motors do
NOT run at the same time via the PWM commands the MCU provides to each
motor in steps as they are needed. Each motor has a rough resistance of
15 ohms and this is for all standard WowWee motors with exceptions in
the Alive series like the Elvis and Chimp. So knowing these 2 units
V=1.5v and R=15ohms the current for each motor at it's max 0.1 Amps.
"Ohms Law = V=IR"
I'll add to this tonight since I have to go to work now.
Jax

... Ugh.

Seems, you did not understand my question. I did not thinked that 5 motors rated at 1,5v each should be connected in series and powered by 7,5v...  Wink I just asked,  how her motors subsystem can be powered by 6v from her left leg which contains only 4,5 (3x1,5) v? Maybe, one of the 1,5v elements from right leg also involved in motor power?

And seems, it would be tough for me to understand all what you had written above (I'm not an english-speaker, after all). Maybe you can explain her power wiring more clearly?

But thanks anyway as you told many useful technical facts abot Femi and WowWee's motors power ratings.

P.S. Sorry for overquoting...

Shai Alyt NEMO
Shai Alyt NEMO's picture

At last, a progress on the Femi modding (maybe, it's a spring coming ;)...

Last weekend I made some independant investigations on her power subsystem and this is what I found:

Every leg of a Femi have 1 separately wired AA cell (1,2-1,5v) and 2 AA cells, connected in series (2,4-3v). And it looks, like in both legs upper 2 cells in her boots (1,5+1,5=3v) make her "brain power" and bottom 4 cells (3+3=6v) are for "motor power". The power switch appears to interrupt not +3v and +6v lines (as I expected), but grounds (0v) for both branches of power. What is still unclear to me - why are the grounds for +3 and +6 circuits not connected together at the battery compartment and are switched separately? But at least after the power switch they seem to come together. So, I made up my mind to try...

Then at yesterday's evening (with slight tremor in heart Sealed) I quickly soldered 2 secondary power sources for +3.3V (on LF33) and +6 (on LM7806) with commom ground, wired them to the mainboard, where the wires from batteries come, powered that all from +9v DC and clicked the Femi's switch... And voila! She came to life without any batteries in her boots!!! The way to powering Femi from mains is open!

BTW, after some time spent in "Posing Mode" I found LM7806 considerably warm. Not as good as I expected. Undecided Have to measure the consumed currents for +3v and +6v power.

Now it's time to think, how to place all that stuff in her feet and how to make power auto-switching from batteries to mains and vice-versa. Probably, I will use an electro-magnetic relay for this purpose.

More to come soon (with photos). Stay tuned.

 

Shai Alyt NEMO
Shai Alyt NEMO's picture

Here is the schematic of Femisapien's battery compartments (see also in thread's gallery):

I think, identically colored wires (Green-Green and Blue-Blue) are connected together somewhere on mainboard thus making:

"Brain Power" (3v): 

+ Green/Red 

- Green/Yellow

"Motor Power" (6v):

+ Orange

- Black

The "-" poles of both power branches have fuses to protect electronics in case of short-circuits or motors overload.

This is confirmed by measuring with multimeter.

theinterceptor
theinterceptor's picture

Can someone tell me where in Femi are the 2 fuses referenced found? What panels need to be removed to access?

Thanks

GWJax
GWJax's picture

 

theinterceptor said: Can someone tell me where in Femi are the 2 fuses referenced found? What panels need to be removed to access? Thanks

theinterceptor said: Can someone tell me where in Femi are the 2 fuses referenced found? What panels need to be removed to access? Thanks

Her fuse is in the LEFT foot, you can see most of the ripdown in my gallery here and this picture is showing the fuse board.

 

Jax

 

Shai Alyt NEMO
Shai Alyt NEMO's picture

Actually there are two fuses in Femi's power subsystem (at least in mine specimen) - one for 3v "brain power" and another for 6v "motor power" (see my schematic). They are yellow and look similar to a ceramic capacitors. Also, you may recognize them as they are commected in series with batteries.

One is visible after removing left leg shell (soldered directly to a battery contact tab). To access another, you have to remove the actual battery compartment part from the left boot.

To GWJax: Sorry, but what you are showed is not a fuse. These two grey cylindric components are tilt switches (ball type, no mercury, so greenpeace can sleep peacefully Wink). There are two of them placed at 45 degrees to ground level for Femi to distinguish between falling face-up and face-down.

GWJax
GWJax's picture

yea I know it the orange fuse on the other side. I did not have a picture of the fuses so I just showed where one fuse was located on the leg location. Thanks for clearing this up for me NEMO.

Not sure if you knew this but but I'm sure you did, there is another tilt switch on the main board as well. Hey what can I say I had my meds in me at the time of the post..LOL

Jax