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Topic: Power standalone atmega328 and servo motor via 9V battery (Read 2648 times) previous topic - next topic

Hello everyone,
i want to power the arduino chip (standalone- not on arduino board) which is 5V btw and a servo motor which needs 6V to operate (well it operates also at 4.8V but with less torque..)

I have a 9V battery, an 7805 regulator (9V to 5V) some 10uF caps and a potensiometer.

How do i do that?

fungus

With only those components?

Your motor's going to be running at 5V...
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retrolefty

Well before you dive into details, are you sure your 9 vdc battery can supply the current requirements for a servo? What kind of battery specifically are you working with? Small 9 volt batteries designed to power smoke alarms just don't work for servos that have motors in them.

Lefty

you mean that the 9V battery doesn't have the amperage to start the motor or that it will drain the battery quickly?


dc42


would you suggest 4 AA batteries instead?


Yes, that will cost you a lot less in batteries.
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ok how about power? 4 AA's are more powerful than a 9V through a regulator?

TeslaIaint

Four AA batteries won't work with your 7805 because you'll need at least 7 volts input (look up your specific 7805's data sheet for specifics). I use 6 AA batteries for input. A 7805 and a 6V regulator in parallel from your 6AA batteries would probably work ok. Don't forget to decouple. http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

zoomkat

If you are going to more than ~8v power supply, then you could make a setup like below to supply 5v to the chip and 5.7v to the servo. If you use a 6v power source, a diode in the supply to the chip would reduce the voltage to ~5.3v.

Google forum search: Use Google Advanced Search and use Http://forum.arduino.cc/index in the "site or domain:" box.

dc42

As your servo need 6V, the obvious solution is 4 AA alkaline cells, feeding the servo directly, and feeding the atmega328p through a silicon diode.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

ok got it! thanks everyone!

but, cost aside, which is more preferable, to drive the motor with 4 AA's or with a regulated 9V battery.

i've read somewhere that 4 AA have more amperage than a single 9V (regulated to 6V of course)

dc42


but, cost aside, which is more preferable, to drive the motor with 4 AA's or with a regulated 9V battery.

i've read somewhere that 4 AA have more amperage than a single 9V (regulated to 6V of course)


You can find relevant information at http://data.energizer.com/.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

so, i decided to go for the 4 AA rechargeable batteries. 4*1.2=4.8V right?

WRONG!
these eneloops i bought give 5.67V, that means 1.4 each.

so the atmega328 can hold 5.5V. if i connect 5.67 will it burn? i mean for 0.17 Volts?

afremont


so, i decided to go for the 4 AA rechargeable batteries. 4*1.2=4.8V right?

WRONG!
these eneloops i bought give 5.67V, that means 1.4 each.

so the atmega328 can hold 5.5V. if i connect 5.67 will it burn? i mean for 0.17 Volts?


6V is the MAXIMUM voltage so you should be ok, but I would just toss in a series diode to drop the voltage a little more.
Experience, it's what you get when you were expecting something else.

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