Author Topic: please suggest the best servo for me and a 9v battery pack...  (Read 4848 times)

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Offline robonoobTopic starter

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please suggest the best servo for me and a 9v battery pack...
« on: December 15, 2007, 03:47:53 PM »
HI :)
as the title says I'm looking for a perfect servo :) well...I've been looking from everywhere... but i don't know what to buy now...what I'm looking for is a lightweight servo that no more expensive than 10 dollars from a place where i could order it to Estonia and i could pay with a VISA creditcard or bank transfer...
and second: also a lightweight rechargeable battery pack(9V) and preferably with 2,1mm barrel plug(not necessary but very usefull for the arduino board I'll be using it for)as cheap as possible of course :)
thank you :)
PS: as i said I've looked from google and from ebay and everywhere but i didn't wind the right to buy...
PSS: i need three of a kind

thank you.

Offline Trumpkin

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #1 on: December 15, 2007, 03:53:50 PM »
Here is a servo that is less than $10 http://www.servocity.com/html/hs-311_standard.html
Robots are awesome!

Offline robonoobTopic starter

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #2 on: December 16, 2007, 02:22:18 AM »
Here is a servo that is less than $10 http://www.servocity.com/html/hs-311_standard.html
okei I'll think about these :) thanks for ur suggestion :)
anyway... the battery pack too... 9V and rechargeable and lightweight...
PS:i see mini servos everywhere but i was wandering that do u people use these mini servos or standard size? and is there a difference in torque or velocity in them?
PSS: this servocity doesn-t ship to estonia :S so can anybody reccomend me another place where i could buy the same servos?
« Last Edit: December 16, 2007, 02:26:18 AM by robonoob »

Offline Trumpkin

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #3 on: December 16, 2007, 07:33:38 AM »
people usually use standard size servos unless you making a flying robot or something really tiny.
Robots are awesome!

Offline robonoobTopic starter

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #4 on: December 16, 2007, 10:40:03 AM »
people usually use standard size servos unless you making a flying robot or something really tiny.
okei thanks :)

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #5 on: December 16, 2007, 10:46:27 AM »
Quote
lightweight rechargeable battery pack(9V)

Why 9V?

This company might ship batteries to Estonia . . . your country isn't on their evil country list . . .
http://www.onlybatterypacks.com/shipping.asp

Just check the shipping on these companies:
http://www.societyofrobots.com/robot_parts_list_battery.shtml

Offline robonoobTopic starter

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #6 on: December 16, 2007, 11:38:18 AM »
hi again :) these two things cought my eye : http://www.robotshop.ca/home/products/robot-parts/power-systems/batteries-chargers/lynxmotion-bat-02-rechargeable-battery.html and http://www.robotshop.ca/home/products/robot-parts/power-systems/batteries-chargers/lynxmotion-smart-charger-usc-02.html
but the battery is 1600Ma and the recharger is 900Ma
so does it mean i couldn't recharge this battery with this recharger?

Offline Admin

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #7 on: December 17, 2007, 05:29:06 PM »
It appears that charger can only peak charge at 900mA . . . thats a lot!

Your battery doesn't have listed specs, but I'm 99% sure bad stuff will happen if you use that charger on that battery. You want more like 400mA max.

Offline david_or_johnny

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #8 on: December 17, 2007, 10:32:56 PM »
900 mA is fine. Is it a peak charger?

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #9 on: December 17, 2007, 11:04:38 PM »
Quote
900 mA is fine
Without specs it is impossible to say for sure. There is a good chance it will overheat and become damaged, reducing the battery lifetime.

Offline robonoobTopic starter

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #10 on: December 18, 2007, 08:03:51 AM »
umm
 i dint get it... :S Lynxmotion BAT-02 7.2V/1600 mAh Ni-MH Rechargeable Battery it says clearly 1600 mAh...or is mAh something different than mA?? oh and look at this: http://www.adafruit.com/index.php?main_page=product_info&cPath=17&products_id=63&zenid=08af919b6db172e1cfb41013dd1c57c0 if I'd buy 9V battery then could i recharge it with this power adapter?(i read somewhere that i dint really need a recharger but i could recharge batteries with power adapters too)
anyway... I'll be using this 9V for my arduiono robot and i hope it wont burn my servos and IR sharp range sensor...or will it?
oh and if there is a difference between mAh and mA then please tell what is it :D

thank you :)

Offline david_or_johnny

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #11 on: December 18, 2007, 09:24:10 PM »
mAh is mA over time. mA is a measure of current, mAh is a measure of capacity. So a 4200 mAh battery is capable of delivering 4200 mA of current in one hour before depleting. Usually for batteries, inexpensive ones are rated higher than actual capacity and fancy ones are rated lower than capacity. I get 4400+ mAh on my IB4200s.

Offline Ro-Bot-X

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #12 on: December 19, 2007, 12:33:47 AM »
umm
 i dint get it... or is mAh something different than mA??

anyway... I'll be using this 9V for my arduiono robot and i hope it wont burn my servos and IR sharp range sensor...or will it?
oh and if there is a difference between mAh and mA then please tell what is it :D

thank you :)


This guy does not understand to Read The Fine Tutorials! - read the Battery tutorial, it explaines there what is mA and mAh.
About the 9V battery. I allready told you that the servos should be connected directly to the battery and will work up to 7.2V. 9V battery most likely will fry them. I don't think you want to see all your money go up in smoke, DO YOU? And the sensors will be connected to the 5V regulated so they are fine with any power voltage.
Check out the uBotino robot controller!

Offline david_or_johnny

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #13 on: December 19, 2007, 08:51:21 AM »
Watch out: some servos are only rated for 4.8v or 4.8 - 6.0v!

Offline robonoobTopic starter

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #14 on: December 19, 2007, 12:41:28 PM »
umm okei then...I'll use 7.2V batteries then... but how many mA should the battery have? ( any calculation didn't tell me that  :-[ )

Offline airman00

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #15 on: December 19, 2007, 01:00:59 PM »
umm okei then...I'll use 7.2V batteries then... but how many mA should the battery have? ( any calculation didn't tell me that  :-[ )

If you use 7.2V you are  shortening the lifetime of the servo

use Admins battery calculator http://www.societyofrobots.com/battery_calculator.shtml to find out what battery you need
 
Check out the Roboduino, Arduino-compatible board!


Link: http://curiousinventor.com/kits/roboduino

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Offline robonoobTopic starter

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #16 on: December 19, 2007, 01:28:16 PM »
umm okei then...I'll use 7.2V batteries then... but how many mA should the battery have? ( any calculation didn't tell me that  :-[ )

If you use 7.2V you are  shortening the lifetime of the servo

use Admins battery calculator http://www.societyofrobots.com/battery_calculator.shtml to find out what battery you need
 


http://www.societyofrobots.com/robotforum/index.php?topic=2573.0 look at this, the Admin explains why i should use 7.2V :)

Offline airman00

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #17 on: December 19, 2007, 02:28:47 PM »

Like I said before:

If you use 7.2V you are  shortening the lifetime of the servo




The servos will work, don't get me wrong, just instead of lasting 2 years they'll last 1 year, something like that  :P

Oh, what are you building?
« Last Edit: December 19, 2007, 02:38:08 PM by airman00 »
Check out the Roboduino, Arduino-compatible board!


Link: http://curiousinventor.com/kits/roboduino

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Offline robonoobTopic starter

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #18 on: December 19, 2007, 02:32:12 PM »
where does he say that?

im saying it would work, but would shorten the life

maybe 7.2V for the regulator
oops sorry it wasnt admin :D anyway (quote): As far as I understand the 9V pin provides the same voltage as the input battery, so when you use the 6V battery
as input, the 9V pin will provide these 6V.

It should work, but not with a 6V battery. It needs at least 7.2V to properly power the Arduino board. Ok, here is why: there is a diode to prevent accidental power voltage swapping and the voltage regulator is not a Low Dropout. The voltage drop on the diode is 0.7V plus the voltage drop on the Vreg of 1.2V, makes almost 2 volts over the 5 volts of the output. That means 6V battery is out of the question. If you replace the diode with a wire and replace the Vreg with a Low Droput Vreg (like LM2940), then you can use a 6V battery to power the servos directly and the board.

But the servos should work at 7.2V. This is what I am using for my CD-bot. CD-bot is a $50 robot in a  round CD case that I am building to test out code for pathfinding and object finding using an AVRcam.

PS: could i use any battery that  matches my required voltage(7.2V) and has a large mAh?
but i have 3 servos do i still need the same voltage if i would use 1? and i have a IR sensor which woltage i dont know...do i have to use another battery for that? :S
« Last Edit: December 19, 2007, 02:39:48 PM by robonoob »

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #19 on: December 19, 2007, 03:02:35 PM »
I recommend aiming for maybe 30 minutes to an hour of runtime.

So if you have three servos that each drain .5A continuously, then you'd want:

3 * .5A = 1.5A

so for one hour:

1.5A * 1h = 1.5Ah battery

(my calculator will do more complex calculations for you)

Offline airman00

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #20 on: December 19, 2007, 03:02:55 PM »



also if you want to go down from 7Vto 6V just put a diode in between the servo and power (it'll drop the voltage down 1 volt)

Check out the Roboduino, Arduino-compatible board!


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Offline robonoobTopic starter

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #21 on: December 20, 2007, 08:00:25 AM »
omg i just found 6 NiMh rechargeable batteries 600mAh each :P and i have a recharger too :P so i can just put them together and i have my 7.2V and 3600 mAh isn't that perfect :P? oh but could anybody give me an advice how to connect all these batteries together?
admin i don't think i will ever let my robot run for an hour :D maybe 10 minutes max :D i mean continuesly :D
or do u turn on ur robot for a whole hour sometimes?
but still do i have to use another battery for my IR range finder? and does anybody know how many volts does a IR need anyways?

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #22 on: December 20, 2007, 08:10:52 AM »
Quote
admin i don't think i will ever let my robot run for an hour Cheesy maybe 10 minutes max Cheesy i mean continuesly Cheesy
or do u turn on ur robot for a whole hour sometimes?
I think you will find it very annoying to only have 10 minutes to program and test your bot before a recharge, dont you think? :P

Quote
do i have to use another battery for my IR range finder? and does anybody know how many volts does a IR need anyways?
power it from the 5V regulator

Quote
omg i just found 6 NiMh rechargeable batteries 600mAh each and i have a recharger too so i can just put them together and i have my 7.2V and 3600 mAh isn't that perfect? oh but could anybody give me an advice how to connect all these batteries together?
power bus

Offline robonoobTopic starter

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #23 on: December 20, 2007, 08:23:35 AM »
Quote
admin i don't think i will ever let my robot run for an hour Cheesy maybe 10 minutes max Cheesy i mean continuesly Cheesy
or do u turn on ur robot for a whole hour sometimes?
I think you will find it very annoying to only have 10 minutes to program and test your bot before a recharge, dont you think? :P

Quote
do i have to use another battery for my IR range finder? and does anybody know how many volts does a IR need anyways?
power it from the 5V regulator

Quote
omg i just found 6 NiMh rechargeable batteries 600mAh each and i have a recharger too so i can just put them together and i have my 7.2V and 3600 mAh isn't that perfect? oh but could anybody give me an advice how to connect all these batteries together?
power bus
through the 5V regulator u mean i still have to buy another battery? or can i just take two wires from the same battery and connect them to 5V regulator as well as to 9V regulator?
and can i solder wires to these batteries and make them into a pack? or should i buy a 6*AA battery holder(does these things even exist? :D) and then just with a 2.1mm barrel plug i connect it to where it is needed...
PS: umm i think i just messed up something :D if i put the 7.2V into the external power plug of the arduino then can i get power from the 5V pin too?

Offline Admin

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #24 on: December 20, 2007, 08:47:16 AM »
You should put some more thought into your questions, many of the answers would be obvious when you sit down and try to figure it out, google search, etc.

Search google for answers, and draw up a schematic for us to look at.

We will let you know if it is correct . . . I'm confident you can figure it out on your first try, you just need to put in the work . . . ;)

Offline robonoobTopic starter

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Re: please suggest the best servo for me and a 9v battery pack...
« Reply #25 on: December 29, 2007, 11:04:13 AM »
You should put some more thought into your questions, many of the answers would be obvious when you sit down and try to figure it out, google search, etc.

Search google for answers, and draw up a schematic for us to look at.

We will let you know if it is correct . . . I'm confident you can figure it out on your first try, you just need to put in the work . . . ;)
yea i know i would come up with an answer but i still woulnd't know if the answer is right or wrong... and thats why i-m asking you people :) cuz ur much much smarter than me :D

 


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