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Best way to power the Domino off 6V?


#1

I’m investigating ways to power my Domino on my RC car project when I realized that through the BEC circuit on the ESC, I would get +6V@ 1A out on the ESC’s power pin.

Rather than install an additional battery pack or try to fork the power from the ESC battery with my own PS, I’d like to see if I could power everything off that.

Basically, my question is: What’s the best way to connect the 6V to the FEZ?


#2

FEZ needs 3.3V only but the 5V is needed for the USB device (on USB host connector)
So, if you do not want to use USB, can feed 6V right to the 5V pin


#3

You may be able to drop the voltage with a 5v Zener.


#4

Why not make up a short wire with the coaxial power plug on it and plug right into the Domino’s power jack?

Also, the power coming off the ESC may be really noisy , you’ll need to look at it with a scope to see. You may need some additional filtering to avoid causing problems on the Domino.


#5

I’m fairly sure it’s going to be a clean signal, but I will definitely check it before I hook it up to the Domino.

Remember, the power coming out of that is usually used to drive a digital receiver, so it’s gotta be somewhat stable.


#6

Oops, I didn’t see Jeff’s other comment before…

Gus, would this work? I think this is just under the input voltage range.


#7

6v is not enough but you can try


#8

I would swear I saw 6V somewhere as I rummaged through my box of old wall warts to find a 6V one. I’m using one and it works, but it is a pretty hefty one that will put out about 2A so with the light load it is likely running a bit over 6V. It would be worth trying to see if it works.

Looking at the schematic it is clear that Gus is right that the 5V is only used for the USB, but is you use a shield that depends on 5V or you accidentally plug something into the USB port you might not be happy with the result. :wall:

You can find filly encapsulated DC-DC converters for less than $10 now that would give you a nice clean 5V out of your 6V. Or it might be just as efficient to use a diode or two in series (voltage drop) between the 6V source and the 5V input, it depends on the current draw of the Domino.


#9

Well,

I am now looking at separate BEC units. Some of these are advanced enough to supply a programmable voltage. So theoretically, all I need to do is get one, program it for 5V and hook it up directly to the RC battery through a splitter.

I am specifically looking at this model: http://www.amazon.com/gp/product/B000MXAR12/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B002ITEL42&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0TB7ZVTPS6E2Q8RYCQ16

I especially love this warning on the page…

[quote]WARNING:
CHOKING HAZARD – Small parts. Not for children under 3 yrs.[/quote]

What the hell kind of three year old wants to play with a BEC unit?? Frikkin lawyers…


#10

just a little (dirty) way which came up my mind:

You can add a Rectifier Diode(1N4001~7). One diode will reduced the voltage by 0.7V. If you will use 6V and add a diode, the result is 5.3V and that will be fine for 5V. Each diode you will connect in series will reduce the voltage by 0.7V.
8)


#11

That’s another option I was thinking about. I think this might be the best one so far, since I do need to use USB for my GPS receiver.


#12

Hee chris,

why not use the 5V in/out pin of the board to power the Domino. you then only need a zener to drop the voltage a bit.

greetings
Niels


#13

I’ve been successfully running the FEZ w/ an RS232 shield off of 6V from a benchtop variable DC power supply. I just use the main power barrel connector split out into leads onto which I can either solder my final connectors or attach my bench PS.

When I check the voltage on the 5V header it’s still only 4.66V, so I don’t believe I’m damaging anything. This is the same value I get when I run off just USB power anyways. Upping the supply to the minimum rating of 7V gets me exactly 5V on the headers.


#14

6V will probably work fine but when you talk batteries, it is not going to be 6V. It will drop very quickly :wink:


#15

How much do you have connected to the Domino when it’s connected like that?

Like I said in the other RC car thread, I think I’m going to need to just get a separate SMPS for the electronics. The BEC in the RC car only supplies 1amp @ 6V which is probably too little to run everything off of. Hell, the servos alone are going to consume a big portion of that.


#16

It’s regulated, so it will be 6V as long as it can be until it shuts off completely. It should never drop by any large margin due to battery fatigue.


#17

Oh, I didn’t know…then why not give it a try.


#18

I think I will. Worst comes to worst I’ll have to spend $45 to get a new power supply. Best comes to best and I’ll be set and won’t have to do anything.


#19

I just bought a 9 volt adapter, is that going to be a problem?

http://cgi.ebay.com/2-x-9-Volt-battery-adapter-Arduino-/200488853899?pt=LH_DefaultDomain_0


#20

No, 9V is what you are suppose to be driving it with. 6V is a little bit low, which is what I am trying to use.