Power Supply - don't want to fry anything
Hi folks,
I have a BOE-BOT (Rev C), and want to add on a bunch of accessories. I have a nice little table (4' x 8') which I will be using as an environment to be explored and hopefully mapped at some point. Given the fact that it is in a nice contained area (with 8" walls all around the table), I am hoping to run my BOE-BOT off of electricity rather than batteries - at least while doing all of the calibration and testing.
I have already purchased from Parallax the "7.5 VDC 1 amp Power Supply - Item 750-00009".
If I set the pin to Vdd, is it then OK to run the following all at the same time:
- 2 wheels
- Ping
- Ping servo
- IR remote
- Digital Encoder Kit
- Compass
- LCD
- and possibly the accelerometer
I'm guessing it would be OK, but having reassurance from a more experienced user would be greatly appreciated.
Thanks very much in advance.
Best regards,
David
I have a BOE-BOT (Rev C), and want to add on a bunch of accessories. I have a nice little table (4' x 8') which I will be using as an environment to be explored and hopefully mapped at some point. Given the fact that it is in a nice contained area (with 8" walls all around the table), I am hoping to run my BOE-BOT off of electricity rather than batteries - at least while doing all of the calibration and testing.
I have already purchased from Parallax the "7.5 VDC 1 amp Power Supply - Item 750-00009".
If I set the pin to Vdd, is it then OK to run the following all at the same time:
- 2 wheels
- Ping
- Ping servo
- IR remote
- Digital Encoder Kit
- Compass
- LCD
- and possibly the accelerometer
I'm guessing it would be OK, but having reassurance from a more experienced user would be greatly appreciated.
Thanks very much in advance.
Best regards,
David
Comments
The regulator on the BOE is rated roughly at 1 Amp. It shouldn't overheat at 7.5V input although it might overheat with a 12V input at that current.
That is a different approach then what I thought - I was wondering more if I would fry anything, but I'm getting the impression that you are wondering if that power adapter could handle the load. Did I understand that correctly? BTW, if it hits the wall, it won't stay there for more than a second or so as I'll just move it out of the way (I'll babysit it).
Thanks for help.
David
So, if you use a wall-wart (the 7.5 volt DC, 1 Amp thing you plug into the wall) rated at 1 amp, or 2 amps, the BOE-Bot will STILL only "sip" the amount of current it needs -- having available a "larger current" is not the same as "forcing" that larger current down the BOE-Bot's throat. And the current situation is that the current is NOT forced down its throat.
Now, a much much larger voltage WOULD "force" current down it's throat, so that would be bad. Thus we don't use DC supplies larger than 20 volts or so.
The governing equation for this is "Ohm's Law" -- V = I * R, or Voltage is equal to Current Times Resistance. Although it's easier to understand this as I == V / R, or the Current in a branch is equal to the Voltage across that branch, divided by the Resistance of that branch. Because, the "Voltage" across a branch is the "driving function" here -- the current is a 'result' of the amount of voltage across the branch.
Maybe I'll even stick with rechargeable batteries (with the Boe-boost) so I don't spend a fortune on regular batteries.
Best regards,
David
If you get a regulated supply for the accys you could make it safe to your needs in two ways. Insert an in-line fuse(the are available in mA versions if so desired. And/or install a current limiting resistor of the proper resistance and power rating.
This is a pretty good way to keep it simple and safe for your testing phase.
Edward
David