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Topic: Arduino with 12 servos (Read 4 times) previous topic - next topic

SteNull


Aniss1001

Thanks mem..you've been of great help..

And I'll keep your estimate about the actual total current draw in mind when I go shopping tomorrow....

Aniss1001

A follow up on the tale of the 12 servos...Never would have thought it would be so tricky and expensive to power these little things...

I managed to find one of these today (capable of 5V 8A):



...and apparently no fan necesary (I asked in the shop). Unfortunately it costs 30 us$ (without cable or anything) which is somewhat expensive (for a "dirty" solution like that)..

I also checked some ATX's and the cheapest ones here go for around 20 us$. But I was unable to find any below 400-450W. I'll probably not use more than 50 (at peaks) even if I add a few more servos and they all stall at the same time (according to mem's judgement?). So having a 450W beast running seems kinda crazy, quite a waste and perhaps even dangerous??

On the other hand I don't know enough about electricity to determine whether that's gonna be a problem. The 145W seemed pretty high to begin with. But 450 sounds just cracy..

The strange thing is that these 400+ beast could only supply 10A at 5V, while the ideal ATX of 145W could supply 14A at 5V?!

Perhaps related to what Ran mentioned earlier (that 5V is becoming less commonly used in modern PC's)..?!

Quote
I would definitely suggest you look for an old AT-style PC to scavenge a power supply from first.  An AT is better than an ATX because you're more likely to find one for free,  and its main output will be 5V,  instead of 3.3V.


And about shipping things to argentina. It's not just painfully slow and expensive. But also risky. So you'd wanna use one of the better shipping services, if you actually want to receive your stuff...which makes it more expensive. Then there is the customs. They generally add 50% to electronics goods (allthough you CAN get lucky and you wont pay anyhting). Furthermore they can take weeks (if not months) to "process your case"...

Alltogether a pretty bad setup :(

The other option is buying things here. It's generally (talking electronics) 50-100% more expensive than USA (worldwide) prices, and it's very difficult or imposssible finding anything just a bit out of the ordinary (like a 145W-399W ATX).

Why did I move here again  ??!!  :-/ ah yeah, the meat and wine is cheap as hell and of sublime quality... And the women are truly stunning..hehe :)

Anyway tomorrow I'll follow Ran's advice and go look for an old/used ATX/AT (if possible). And I'll also check out a local indutrial electronics parts shop for cheaper 5V 8A single output supplies...


Hasta luego

SteNull

Hola Aniss.
check out the RC market. They got a thing called BEC.
i got Castlecreations BEC it can be driven from 5v to 25v and at 12V it has a peak at 7A, with output voltage from 4.8V to 9V. so if u want 6V and 5A on sec side u need 12V and 2.5A + some lost, on prime side.
Maybe not the thing your looking for... its early in the morning and i wanted to write something  ;D

Aniss1001

Hola SteNull!

Sure sounds like a neat product... But it doesn't really solve my problem.  ;D

I need a stable, regulated, ac/dc converter 5V/8A (min.) for long hours of robot programming/experimentation. And they're just not so easy to come by.

But I think I've decided on the cheap solution: Building a robot power supply from an AT(X). I finally found a place that sells used AT/ATX supplies not too far from my flat:

http://www.compucanjes.com/products/search/?starting_point=1;category=40;subcategory=174;sortBy=price+ASC;sub1=865

The prices are in pesos (divide them by 3.8 and you've got us$), so they're pretty damn cheap. Plus they've got some very low Watt AT's as well. :)

Anyway thanks for the input...and goodnight...here it's 3.25 in the morning and I'm off to bed...

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