Subject:
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Re: Custom sensor current drain - use two sensor ports?
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Thu, 30 Jun 2005 09:13:13 GMT
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Viewed:
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3820 times
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Hi Justin,
In lugnet.robotics.rcx, Justin Fisher wrote:
> I'm building a custom active mindstorms sensor, but it requires 28mA to operate,
> while the sensor port only provides about 15mA. Any advice? (The mA requirements
> of the sensor cannot be halved - improvements may be possible, but it seems
> unlikely I could get it down to 15mA).
>
> I've using a ver 1.0 RCX, do later versions of the RCX give more power to the
> sensors?
No, the internal circuis are more or less the same.
>
> I've tried wiring two sensor ports together, and together they provide enough
> power to run the sensor. Are there any problems with doing this? (I figure I
> could give the sensor two connector-brick wires instead of one, each with a
> bridge rectifier, that way I should be able to connect it directly on top of the
> two ports being used by touch sensors, continue to use the touch sensors, and
> then when I want to take a reading with the custom sensor, switch their type to
> light sensor, thus powering the new sensor, then, switch back to touch when
> done.)
I don't think you could break something. But of course using two input ports is
not so great...
>
> Can anyone think of any better way to solve this? I'd prefer not to put
> batteries in a sensor, that seems wrong. I'd love to have it work with just one
> wire like a light sensor, but I'm guessing the higher power requirements just
> rule that out :(
You might try the kind of trick I used for my GP2D12 sensor
(http://philohome.com/sensors/gp2d12.htm): store energy in a capacitor, and use
it during a small time frame. You could for example power the sensor during only
1 out of 4 sensor scan cycles, and use a sample and hold circuit to maintain
output value available to RCX. Of course this assumes that your sensor can
operate in that short period and that a 4ms sample period is short enough for
your application...
BTW, what is this sensor???
Cheers,
Philo
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Message is in Reply To:
 | | Custom sensor current drain - use two sensor ports?
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| I'm building a custom active mindstorms sensor, but it requires 28mA to operate, while the sensor port only provides about 15mA. Any advice? (The mA requirements of the sensor cannot be halved - improvements may be possible, but it seems unlikely I (...) (19 years ago, 30-Jun-05, to lugnet.robotics.rcx)
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