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Getting 9V from Vcc on Baby Orangutan

#1

I hope this isn’t just my lack of understanding showing, but I’m measuring 9 volts coming from the Vcc output on my Baby Orangutan (328p). Here’s a picture of my setup - I’ve cleared away all the other wires.


I’ve got a 9 volt battery pack under the shelf that the breadboard is attached to. It’s putting out about 9.6 volts. The wires from the battery are attached to the little header block plugged into the breadboard.

I’m feeding that into VIN and measuring Vcc by putting the tip of the red probe from my multimeter in the Vcc hole (top left, right next to M1B, and the black probe against the black wire coming from the power rail.

If I’m reading the user guide correctly I think I should be seeing 5 volts, but I’m seeing 9.1 volts. Am I just misunderstanding, or setting this up wrong?

Thanks

Joe

#2

Hello, Joe.

You are not connecting the Baby Orangutan’s ground. The ground of the Baby Orangutan should be connected to the ground of the battery. In general, unless you are doing something advanced, you will want all the grounds in your system to be connected together.

- Ryan

#3

Thanks, that was it. I saw it in the user guide too but just didn’t think about it. Sorry to be such a nug.

Thanks

Joe

#4

Hello.

Are you using a 9V battery or a 9V pack? If you are using a 9V battery, I suggest you consider using a different power source for your robot. 9V batteries cannot deliver much current and are poor choices for applications such as driving motors.

- Ben

#5

Actually I had a NiMH pack made up at a local battery store, I’m not sure it works as well as it should though. I substituted a six AA battery holder and everything ran much better. It’s reading 9.6 volts, but maybe needs to be recharged again anyway.

Thanks

Joe

#6

Ah, I was confused because you can’t get 9V with a pack of NiMH cells (a 7-cell NiMH pack would have a nominal voltage of 8.4V and an 8-cell pack would have a nominal voltage of 9.6V). How many cells were in your battery pack? An NiMH battery pack should work just fine for a small robot like yours. What makes you think it wasn’t working as well as it should? Did you charge it before you used it?

Six alkaline cells would have a nominal voltage of 9V, so I think you have plenty of juice left in them if you’re seeing 9.6V.

- Ben

#7

Yes, I charged it before using it. It has 8 cells, so I guess it’s putting out the right voltage. The reason I was wondering is that when I used it to power the baby orangutan, the power light just barely came on, and the LED didn’t blink at all (I have the BlinkLED test program loaded at the moment). When I used the six AA pack it came on full blast.

Looks like the NiMH pack is putting out 2.1 milli amps according to my multimeter. Maybe I need to redo the connector, that doesn’t sound like enough.

Joe