Powering the quickstart
Graham Stabler
Posts: 2,510
Hi Guys,
How are people powering the Quickstart for stand alone operation? I could hack a USB connector or tack some wires on but is there another way?
Cheers,
Graham
How are people powering the Quickstart for stand alone operation? I could hack a USB connector or tack some wires on but is there another way?
Cheers,
Graham
Comments
<http://www.instructables.com/id/Battery-power-for-the-QuickStart-board/>
The 40 pin expansion header has two pins just for that - pins 39 and 40 -
the two on the far right end. The top row (closest to the edge) is pin 40, which
is wired up as V-IN, the voltage supplied to the on-board voltage regulator.
Pin 39 is ground. That one will be connected to the NEGATIVE side of the battery pack.
I use an angled pin header for the connector to reduce the possibility of hooking the
battery up backwards. That would be bad - very bad!
Great Instructable, cavelamb! Very well done and well illustrated!
Thanks for that, I feel stupid for not spotting this on the schematic, I think I had assumed it was only IO on the connector!
Your idiot proofing is also excellent!
Graham
There's a picture of this method in post #29 of this thread. You can avoid male battery connectors with cavelamb's method if you use long header pins to join the two female connections.
I've been thinking about picking up some of these for a quickstart protoboard.
http://www.adafruit.com/products/373
Graham
A straight pin connector would obviously work just as well - if connected correctly.
The angled set-up takes the worry out of it. As long as the power wires come in from
the same direction, any way. (Please don't ask how I know all that. I'd probably fib)
Varn: I wasn't bending the pins, although you could if you were really careful to not break them.
Just avoid trying for a sharp square bend and it should be fine.
What that piece was about was to press the plastic bar back some to make the pins longer.
Duane: yeah baby. I like that female/female suggestion a lot. No exposed metal on either end.
I already have two wall warts set up for breadboarding. (one +5 3 amp regulated, one +12 2.5 amp regulated)
so I'm ok for now. But it is a real good suggestion...
However, I think I'll add another header to the little power like you did. That way I can still use the I/O connector
for plug-in boards and not have to attach the battery to the plug-in.
I'm a little henky about soldering on these little boards. Especially when getting anywhere near the SO and surface
mount stuff. My hands aren't as steady as they used to be. But a thru-hole like that I'm sure I can do safely.
I just checked out that extra 8 pin header site.
The bottom row is ground, but the top row is 3.3 volts - not Vin.
That means these pins are tired to the output pin of the regulator.
I understand that these new-fangled regulators are pretty tough critters,
but how well would they take to a 3.3 volt input on the output pin?
I only use those 8 holes for powering other 3.3V devices. I use positions 39 and 40 of the four holes to add my male headers for battery power.
I think another question to be asked is: "How do you get 5 volts to your Quickstart based projects?" For my Shackable Scavenger Hunt project, I am using a 7805 in the Vin/Gnd holes (for 5v out and Gnd on the 7805) and the 7805 input goes through a panel mount switch then to a nine volt battery snap. To get 5 volts to my LCD, I have a wire soldered around the output pin of the 7805. For the next version of the Quickstart board, I would love to see the following added:
- 3 holes for a 7805
- 4 holes for input and output caps
- A 2 pin header for Vin and three holes for a DC Jack
- A double bank of holes for 5v+Gnd pairs (4 holes)
Then you would have options for a wider input voltage range as well as 5 volt access for things like LCDs. Minimal, if any at all, cost increase on the Quickstart because you are simply adding 16 holes.Most of the datasheets I've looked at for 5V devices usually have an allowable voltage range of between 4.5V and 5.5V. Four NiMH batteries stay within this range unless severely discharged. While it's not safe to assume all 5V devices can run off of four NiMH, I'm pretty sure the 5V devices I used regularly work fine with the unregulated NiMH 4-cell packs.
Note: If a 4.8v battery pack is connected to Vdd instead of Vin, the prop gets really HOT. Maybe don't do this. Re-adust bi-focals and re-do the connections. Not that I would know anything about this from experience...
A forward biased 1N4001 (diode) could solve that issue.
1 volt drop from 4.8 would bring it down to 3.8 volts.
( I thought they were .6V forward drop but the data sheet says 1v - http://www.diodes.com/datasheets/ds28002.pdf )
I would take that spec with a largish grain of salt. I found it varies quite a bit with current and temperature. Best to check the voltage drop with a meter and the approximate current draw of the circuit it will used on. Might save a propeller.
Great Instructable.
These are awesome idiot-proof connectors:
http://www.bgmicro.com/search.aspx?find=quick+disconnect
I used them for an LED counter that has over $300 worth of 7-segment displays in it that is used by non-techies.
The numbers came out thusly (under load Quickstart) :
9 volt battery
Extrapolates to .58 volt drop per diode at 9 volts.
Using a the 4 cell AA pack
Call it .55 volts drop per diode at 6 volts.
So, 6.0 - 3.3 = 2.7 volt drop needed; /.55 = 5 diodes.
-Phil
I dunno, Phil.
It sounds like they are talking about BASIC stamp stuff.
and the warning (Be sure the EXT/USB jumper is set to USB.)????
Are we SURE this applies to a QuickStart board?
I just did it on one of my QS boards, and it works fine -- both with external power and powered from my PC through a powered hub. Configured this way, however, it will draw full power as soon as it's plugged in.
-Phil
Hey mojo,
Thanks for that.
Those were shot with a Fuji Finepix S8100 using the macro 2 setting, a tripod,
and some extra fill lighting.
This camera has an 18x optical zoom and really fine optics.
I think it's a very good camera for the money.
How does that compare to grounding pin 30 - as far as power consumption?
Sorry, got distracted and forgot the question that started it all...
4 AA cells make good 6 volts. Tap off one forward biased power diode and call it Vcc.
Depending on what the circuit is up to you may want to add filter caps for high freq noise.
That's about as simple as it gets.
-Phil