Help!!!

When operating on 9v what voltage is seen on the battery, and on the 5v pin.

Is it one of these? .

I'm afraid I don't have a multimeter (its at school). What are you suggesting - that the battery is not powerful enough?

Warwick

If it is a PP3 it is important the voltage does not sag.

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What exactly do you mean by PP3?

Warwick

PP3 = battery size as pictured in Reply #20.

I cannot see the picture - my computer blocked it.

It's a 9V battery with the two terminals on one end. http://www.amazon.com/b?node=389576011

So yes, my battery is a PP3. How will this affect my LCD?

Warwick

The important thing is your hardware must be supplied with adequate power. Get your voltmeter and measure the voltage.

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As I said back in post #21, I don't have a voltmeter - I left it @ school. :( However, I am glad to say that my problem is solved. I used four AA batteries, which of course gives less voltage but has a higher amperage. My screen is no longer blank! I hope to launch my contraption today. :)

Thanks to everyone who helped me!

Warwick

Time to get a voltmeter at both locations ;)

Glad you have things working now. 1x1.5 = 6v If your Arduino is an UNO you need at leased ~7.5v

What Arduino are you using? .

An Arduino Uno! (try to imagine the Italian accent) I have used this before (I once made a remote controlled car) It seems to carry out all the functions I need splendidly. Why do I need 7.5 volts? For stability of the system?

Warwick

The technical specifications for the UNO: https://www.arduino.cc/en/Main/ArduinoBoardUno

Feeding the UNO from the power jack requires 7-12vdc (recommended).

At 7 volts input. There is an input diode drop of .7volts leaving on 6.3v for the on board voltage regulator. The regulator has a max drop of ~1.2v at 800ma so 5+1.2=6.2v 6.2+.7= 6.9v That is, the minimum voltage you need is ~7 volts input.

At a 6 volt battery you are on the verge of under powering the UNO.

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Hiya Larry,

It’s one the verge, or just barely on the other side, at 4.48 volts. I’ve seen lots of projects done with a aa 4 pack as the power source.

Even better (especially for a flying device, since weight is premium) is a 3 pack, giving 4.5 volts, fed directly into the 5V pin, bypassing the 5v (and 3v?) regulator(s). I have read somewhere (possibly here) that the power is considered ‘in spec’ between 4.5 and 5.5 volts on a UNO.

Chris, I too have used 4.5v (3x1.5 fresh batteries) to power the 5 volt pin directly with good success. I have also used 6v through a silicon diode (6 - .7=5.3v) to power the 5 volt pin. I supposed adding a schottky diode for ~.3v more, could also be added.

The OP had problems with a 9v pp3 battery that was probably depleted.

LarryD: Chris, I too have used 4.5v (3x1.5 fresh batteries) to power the 5 volt pin directly with good success. I have also used 6v through a silicon diode (6 - .7=5.3v) to power the 5 volt pin. I supposed adding a schottky diode for ~.3v more, could also be added.

The OP had problems with a 9v pp3 battery that was probably depleted.

Love the diodes! Am I right in thinking that choosing an operating voltage less then 5 volts, the diodes would protect the batteries from seeing a reverse voltage if USB or Vin power is used while the batteries are installed? Like this:

Perhaps this would be useful for students such as our OP? (A couple weeks ago though..., right Mr. Shaw? :smiling_imp: )

ps, @WarwickShaw, please let us know how your launch went. If it was good, pictures would be great!