Tapping power from Activity Board?
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Hi all,
Has anyone found a "nice" way to grab the power off this board *before*
it's supplied to the stamp? I've mounted mine on a breadboard so I have
additional prototyping space and sometimes need more power than the
Stamp's regulator can provide.
The board uses an AC adapter with a DIN plug on the board. I haven't
found a schematic for this board and the documentation doesn't mention
any points available to distribute power to other circuitry other than
the regulated 5V output from the stamp itself.
I'm getting desperate and considering hacking the power cable to supply
a feed prior to the DIN plug, but thats messy and I'd rather tap into to
board if possible. So has anyone found a solution?
Thanks
--
Has anyone found a "nice" way to grab the power off this board *before*
it's supplied to the stamp? I've mounted mine on a breadboard so I have
additional prototyping space and sometimes need more power than the
Stamp's regulator can provide.
The board uses an AC adapter with a DIN plug on the board. I haven't
found a schematic for this board and the documentation doesn't mention
any points available to distribute power to other circuitry other than
the regulated 5V output from the stamp itself.
I'm getting desperate and considering hacking the power cable to supply
a feed prior to the DIN plug, but thats messy and I'd rather tap into to
board if possible. So has anyone found a solution?
Thanks
--
Comments
The Schematic is available from the Product Description page for the
Activity Board.
Kenny
>
> Supply Voltage (VIN) is available at Pin 20 of the AppMod Header.
>
> The Schematic is available from the Product Description page for the
> Activity Board.
Well Poo! Looks like Parallax improved this board and I have an older
version (I hate that!) I don't have the 20 pin Appmod header that is on
the current board. Instead I have an 18 pin post header which only has
Vdd available on pin 18.
Am I correct that Vdd is the 5v regulated output from the stamp with a
50ma limit? If so, I'm still looking for suggestions...
Thanks for you help.
Michael Burr
> 50ma limit? If so, I'm still looking for suggestions...
>
Why not use a a seperate 7805 regulator and supply current from an
external 9 - 12v DC "wall wort" or 9V battery. Just make sure that
the grounds are all connected and use the output from the 7805 to
power higher current demanding things. I've seen 7805s as high as
1.5A.
+
+
| |
|7805 |
| |
+
+
| | |
Power--+ | +---> To higher current requirements
GND
+
|
V
Basic
Stamp
GND
> [noparse][[/noparse]snip]
>
>>50ma limit? If so, I'm still looking for suggestions...
>>
>>
> Why not use a a seperate 7805 regulator and supply current from an
> external 9 - 12v DC "wall wort" or 9V battery. Just make sure that
> the grounds are all connected and use the output from the 7805 to
> power higher current demanding things. I've seen 7805s as high as
> 1.5A.
Thanks, I'd considered that, but I always seem to have troubles
when I start tying grounds from different power sources
together, so I've always tried to keep it clean and have only
one power source. Am I being too conservative here?
What do others think about this? Can you get reliable operation
with 2 seperate wallworts w/ grounds tied together? How about a
wallwort and a 9v battery?? That one really has me stumped -
isn't it possible for ground potiental to be completely
different in that setup??
grounding two of them together should be OK. A switching power supply from a
laptop may not be isolated, so I would be very careful.
Original Message
> >>50ma limit? If so, I'm still looking for suggestions...
> >>
> >>
> > Why not use a a seperate 7805 regulator and supply current from an
> > external 9 - 12v DC "wall wort" or 9V battery. Just make sure that
> > the grounds are all connected and use the output from the 7805 to
> > power higher current demanding things. I've seen 7805s as high as
> > 1.5A.
>
> Thanks, I'd considered that, but I always seem to have troubles
> when I start tying grounds from different power sources
> together, so I've always tried to keep it clean and have only
> one power source. Am I being too conservative here?
>
> What do others think about this? Can you get reliable operation
> with 2 seperate wallworts w/ grounds tied together? How about a
> wallwort and a 9v battery?? That one really has me stumped -
> isn't it possible for ground potiental to be completely
> different in that setup??
source. Battery, wall worts, whatever. It's a matter of
potential...Here's an interesting fact relating to this...The
potential difference between grounds in Florida and Boston is around
1000 volts. They discovered this back in the 50s when running long
distance cable. Another interesting use of this is making the ground
of the 7805 >0v. Need a 10v regulator? Make ground 5v.
> Thanks, I'd considered that, but I always seem to have troubles
> when I start tying grounds from different power sources
> together, so I've always tried to keep it clean and have only
> one power source. Am I being too conservative here?
> Typically the output of a wall-wart is totally isolated from the AC line, so
> grounding two of them together should be OK. A switching power supply from a
> laptop may not be isolated, so I would be very careful.
Thanks all, guess I'll give it a try.
Michael Burr