Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: mohamed on March 06, 2008, 09:45:35 PM

Title: questions about batteries and servos of the 50$ robot
Post by: mohamed on March 06, 2008, 09:45:35 PM

now i got my servos which are HS-322HD and they said that is has speed 0.19sec/60 at 4.8v,torque 3kg-cm
it has 0.15sec/60 at 6v and torque 3.7kg-cm, aslo i got 6 1.2v and 2000ma batteries from radioshack.
my questions are:
1.can i use 5 batteries from the one i got=6v to power whole robot or not?
2.is the HS-322HD servo is good for the robot,also can it be modified like the one in the tutorial or it has another way.
Thanks for your help...

Title: Re: questions about batteries and servos of the 50$ robot
Post by: airman00 on March 06, 2008, 09:50:33 PM

If you use 6V then you don;t need a voltage regulator
( that is assuming AVRs  , like PICs , run at up to 6volts)


HS-322HD are good servos, and they can be modified the same way. I used those servos on my 3 in 1 robot (picture is in my signature)

Title: Re: questions about batteries and servos of the 50$ robot
Post by: mohamed on March 06, 2008, 10:00:34 PM

Thanks airman for ur reply....and btw nice robot i really hope that i can reach this level oneday  ;D
now i have checked the ATmega 8 datasheet and i found that the operating voltage is 5.5v...so i can use the 5 batteries but i have to put the voltage regulator right?

Title: Re: questions about batteries and servos of the 50$ robot
Post by: airman00 on March 07, 2008, 01:07:51 PM

wrong

a voltage regulator needs 2 volts higher to work right. SO a 5v regulator needs 7V coming in.


I think the ATmega 8 can handle the 6V though


But I need to know the minimum and maximum voltages it could handle. Then I can give you the best solution

Title: Re: questions about batteries and servos of the 50$ robot
Post by: mohamed on March 07, 2008, 02:46:41 PM

it says in the datasheet that the ATmega8L can handle voltage from 2.7-5.5v
so what do u think?

Title: Re: questions about batteries and servos of the 50$ robot
Post by: airman00 on March 07, 2008, 02:47:45 PM

I say connect a diode ( which usually have a 1 volt drop) between the batteries and the microcontroller

Title: Re: questions about batteries and servos of the 50$ robot
Post by: Admin on March 15, 2008, 05:44:43 PM

Quote

If you use 6V then you don;t need a voltage regulator

If you are using a microcontroller, no, you need a voltage regulator! Without a fixed voltage, the timer will be all whack, and the ADC won't be consistant.

Quote

a voltage regulator needs 2 volts higher to work right. SO a 5v regulator needs 7V coming in.

All voltage regulators have a 'dropout voltage', typically 1.5V. An LDO, or low dropout, can be as low as .15V. I use a .3V LDO on one of my microcontrollers.

Quote

1.can i use 5 batteries from the one i got=6v to power whole robot or not?

Yes, if you use a LDO regulator.

Title: Re: questions about batteries and servos of the 50$ robot
Post by: airman00 on March 15, 2008, 06:21:39 PM

Quote from: Admin on March 15, 2008, 05:44:43 PM

Quote

If you use 6V then you don;t need a voltage regulator

If you are using a microcontroller, no, you need a voltage regulator! Without a fixed voltage, the timer will be all whack, and the ADC won't be consistant.

Whoops, I've been used to using PIC chips with built-in-regulators like the PIC16F616 ( my personal favorite) .

Yea you're right admin  ;) ::)