View Full Version : powering the stamp(Board of education) with 7.4V lipo
10-23-2009, 08:38 AM
Can I power the BOE with a stamp with a 7.4v 2 cell lipo battery?
If so where can I connect the positive and negative terminals to ?
10-23-2009, 10:29 AM
Why to the power jack of course (or the battery clip). That way you get the benefit of the on-off switch. RadioShack sells matching plugs (2.1mm ID, 5.5mm OD). If you want to use the battery clip instead, be careful because you'll need to connect the positive terminal to the black wire and negative terminal to the red wire of most 9V battery connectors. They're designed for the power load end rather than the power source end of the circuit.
If you don't want to use either of those two choices, you could connect the positive end to Vin and the negative end to Ground. Be sure to use a fuse of some sort. If the battery becomes shorted, it could explode or catch fire. Use no bigger than a 1 Amp fuse.
11-02-2009, 10:42 PM
ok my battery is at 17volts will this fry the board of education? it say 6-9 volts on it?
11-02-2009, 11:49 PM
It does say 6-9 VDC for the input to the BOE. You should not exceed that. If your battery is really putting out 17V, don't connect it to the BOE.
11-02-2009, 11:50 PM
I believe if you connect the battery to the BOE power-connector (Vss is ground), that the on-board linear regulator will be used to supply 5 volts to the BS2.
The result of this is that the linear regulator (that three-pin device standing up) will run a little warm -- but this should not do any damage.
The only thing that could be damaged would be a servo (if you're using servos) if you leave the jumper set to "Vin", because servo's don't like anything over 7.5 volts.
11-03-2009, 01:07 AM
how can i regulate the 17 volts (lipo pack) down before I plug it into the boe? I am not to familiar with electronics.
11-03-2009, 01:12 AM
Use an 8V or 9V regulator like the LM7808 or LM7809. There are plenty of examples of the use of this regulator. Download the datasheet from the manufacturer and look at the example circuits in the last few pages of the datasheet. Fairchild is one manufacturer (www.fairchildsemi.com/pf/LM/LM7809.html (http://www.fairchildsemi.com/pf/LM/LM7809.html)). Look at Figure 10 on the datasheet.
Post Edited (Mike Green) : 11/2/2009 5:17:11 PM GMT
11-03-2009, 01:30 AM
As long as it's DC, you don't need to "regulate it down", there's an on-board regulator to "regulate it down" for you.