Author Topic: 6V AC Adaptors  (Read 2212 times)

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Offline SeagullOneTopic starter

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6V AC Adaptors
« on: September 08, 2009, 12:38:55 PM »
Hi everyone.

Aside from using a 6V 10 AH battery to power a ton of servos on my robot, NINA, I'm thinking of having the servos powered by a 6V AC adapter when the robot is only required to be stationary. However, since there are a ton of high-powered servos on my robot, this AC adapter needs to be able to handle a ton of amps, at least 10 amps to be on the safe side. I'm not sure how many amps the 1/4 scale and other high amp servos are going to draw, but I want to be safe.

Problem: I've googled this several times over, but I can't find any 6V 10 Amp AC adapters. Does anything like that exist?

I've also read on the forum that AC adapters are not regulated, meaning they'll supply a somewhat higher power than rated. But with the amps my servos will probably draw, I don't think voltage regulators would be able to handle the current either.

Any advice?

BTW, I'm using a Lynxmotion SSC-32 servo controller for these servos. There are three 1/4 scale servos, 2 standard sized but high torque servos (333 oz-in at 6V), 4 standard sized servos and about 4 mini servos. In my project so far. I'm also planning to integrate more for further articulation, so I'm looking for something to accomodate for this.

Again, I've googled it several times, checked several stores, but nothing that quite fits my project. Any advice?
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Offline airman00

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Re: 6V AC Adaptors
« Reply #1 on: September 08, 2009, 01:22:55 PM »
Many electrical outlets have fuses to protect from drawing too much. It really all depends on how your outlet is set up, I've seen many being able to handle 8 amps, and some even higher than that.

Assuming your outlet can handle the 10amps, then you can take multiple wall-warts (aka power adapters) and hook them up in parallel ( like a parallel battery). Example: Five 6V @ 2 amp wall warts to give you 6V @ 10 amps.
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Offline madchimp

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Re: 6V AC Adaptors
« Reply #2 on: September 08, 2009, 02:21:41 PM »
Many electrical outlets have fuses to protect from drawing too much. It really all depends on how your outlet is set up, I've seen many being able to handle 8 amps, and some even higher than that.

Don't know where you're from but in the US the standard for electrical outlets is 15amp and some are even 20 amps. That is at 110volts so you run it through a transformer and take it down to 6volts and you can multiply that times around 18 so the only real problem is finding a power supply, don't think you will find a wall wart that can do it probably need to use multiple wall warts or get a true power supply.

Offline Webbot

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Re: 6V AC Adaptors
« Reply #3 on: September 08, 2009, 03:52:55 PM »
If you put many in parallel as Airman has suggested then I'm not sure what happens if they dont all give out an identical voltage. Will it be like causing a short circuit (ie bad)?
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Offline airman00

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Re: 6V AC Adaptors
« Reply #4 on: September 08, 2009, 05:08:58 PM »
If you put many in parallel as Airman has suggested then I'm not sure what happens if they dont all give out an identical voltage. Will it be like causing a short circuit (ie bad)?
That is identical to putting a 3V and a 6V battery in parallel.  What happens is that the 6V battery sends current to the 3V battery , and the 3V battery gets warm, and maybe even blows. I'm not sure about quantifying it, but I think what happens is that the 3V battery draws current from the 6V ( like a motor or any component draws current), while at the same time the 6V and 3V battery in parallel are providing current to the rest of the circuit. So the 3V battery is pretty much a "parasite" on the entire battery system.

 I've seen this problem many times with robots that use two 12V lead acid batteries hooked in parallel( like my Chives). One 12V battery might be a little higher than the other, and therefore charges the lower voltage battery.

In this case, if all the DC adapters are properly grounded to each other and if they are all giving around 12V ( + - 1 volt) I don't think there will be any problem or heating up or frying.
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Offline Soeren

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Re: 6V AC Adaptors
« Reply #5 on: September 08, 2009, 08:18:33 PM »
Hi,

Reality check!

[email protected] is 60VA ("W") and that's around half an Ampere drawn from the mains if 110 or 120V and a close to a quarter of an Ampere if European (230V).

Reality check 2!
That "few" servos aren't gonna eat 10A - make a serious calculation and you'll come to... much less.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline airman00

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Re: 6V AC Adaptors
« Reply #6 on: September 08, 2009, 08:39:42 PM »
Reality check 2!
That "few" servos aren't gonna eat 10A - make a serious calculation and you'll come to... much less.

Quote:
Quote
There are three 1/4 scale servos, 2 standard sized but high torque servos (333 oz-in at 6V), 4 standard sized servos and about 4 mini servos. In my project so far. I'm also planning to integrate more for further articulation, so I'm looking for something to accomodate for this.
Counting all those servos and the possibility of adding future servos, 10 amps seems appropriate. If several or even all of the servos were stalling, which may be possible depending on the application, then the current draw might approach this 10 amp peak. I've had servos draw something like 1 amp each at stall torque.
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Offline SeagullOneTopic starter

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Re: 6V AC Adaptors
« Reply #7 on: September 09, 2009, 01:13:57 PM »
Thanks for all the input guys!

What about this:
http://www.cti-texas.com/cocp6vdcposu.html

Problem is it looks a little heavy, so I likely shouldn't mount it on my robot. But it would be great for my project's docking station, should I decide to build one.
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Offline Soeren

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Re: 6V AC Adaptors
« Reply #8 on: September 09, 2009, 01:36:28 PM »
Hi,

Counting all those servos and the possibility of adding future servos, 10 amps seems appropriate. If several or even all of the servos were stalling, which may be possible depending on the application, [...]
An extremely unlikely situation and even so, you don't operate a motor stalled, so a fuse (wire type or electronic) should deal with that.
Besides, some of them servos are mini-types.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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