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16  Using Arduino / Sensors / Re: Can you use two IR transistors and and IR LED to pan a turret? on: April 12, 2013, 01:03:08 pm
THat's the same amount of work as building the whole thing. I'd like to know so that I can skip that and use a camera if the range isn't going to be good.
17  Using Arduino / Sensors / Can you use two IR transistors and and IR LED to pan a turret? on: April 12, 2013, 11:48:20 am
You would have two IR transistors pointing not quite straight ahead but a little away from each other. They would pan a servo or motor such that they stop when the reading from each Ir transistor was about even, meaning the turret is pointed at the IR led. How far away would that work, roughly, for a normal LED? Are we talking 10ft or 100ft? Has anyone messed with this? If the range is short, is there a better sensor to use besides a camera?

Edit:

What I'm asking about is essentially the same thing as a sun tracker.



except it will need to follow an IR LED or small cluster of LEDs and be much faster on the response time. I know the servo can move much faster but maybe there is something else limiting the speed like the response time of the phototransistor. Do any of you with experience with this stuff thing that it will be able to work with those modifications?
18  Using Arduino / Project Guidance / Re: Arduino + magnetic strip reader + paypal = payment processing machine? on: March 11, 2013, 09:25:46 am
It should be the same as when you're typing your CC info into paypal to purchase something in the situation where you don't have a paypal account. After you've typed the card #, exp date, security #, etc., the web form just simply sends that data to paypal. Paypal makes an CC reader and app for smart phones for this very purpose. I guess I should just use a smart phone with a WiFi connection instead. what do you think?
19  Using Arduino / Project Guidance / Re: Arduino + magnetic strip reader + paypal = payment processing machine? on: March 11, 2013, 08:17:27 am
You're misunderstanding the situation. People will only be using the machine to *deposit* money into my paypal account using a credit card.
20  Using Arduino / Project Guidance / Re: Arduino + magnetic strip reader + paypal = payment processing machine? on: March 10, 2013, 10:34:58 pm
The bottom line is, you're just sending data over the net right? It's essentially just you sending data to paypal. So why cant the arduino send packets over the web? Whatever. So the beagleboard is what I should use then instead?
21  Using Arduino / Project Guidance / Re: Arduino + magnetic strip reader + paypal = payment processing machine? on: March 10, 2013, 08:50:58 pm
why not? where does the arduino fall short?
22  Using Arduino / Project Guidance / Arduino + magnetic strip reader + paypal = payment processing machine? on: March 10, 2013, 01:51:55 pm
Would I be able to use an arduino and this stip reader https://www.sparkfun.com/products/11096 to somehow send payments to my paypal account? Can the arduino handle the paypal api? Has this been done before?
23  Using Arduino / Project Guidance / Re: airsoft gun motor causing servos to twitch on: March 06, 2013, 11:45:00 pm
Quote
The new airsoft gun has a bigger motor.

Are you trying to power it and the servos with four AA batterys?
no.
24  Using Arduino / Project Guidance / Re: airsoft gun motor causing servos to twitch on: March 06, 2013, 10:42:42 pm
DC motors have commutators in them, and when the brushs pass over them, they sometimes hit a gap. This gap cause the motor to loose power for less than a hundredth of a second (depending on speed) and will cause fluctuations in the current. These capacitors help reduce the fluctuations by temporarily acting as a load, and keep the current consistent. Motor diagrams 1 and 2 are both good to use, but I sometimes combine the two diagrams, if needed.
THANK YOU. That's the most competent answer I've seen yet.
25  Using Arduino / Project Guidance / Re: airsoft gun motor causing servos to twitch on: March 06, 2013, 06:39:58 pm
From Wikipedia:
Quote
Another kind of decoupling is stopping a portion of a circuit from being affected by switching that happens in another portion. Switching in subcircuit A may cause fluctuations in the power supply or other electrical lines, but you do not want subcircuit B, which has nothing to do with that switching, to be affected. A decoupling capacitor can decouple subcircuits A and B so that B doesn't see any effects of the switching.

This describes the problem in general but doesn't give an example of specifically where the best place to put them would be. You can put one near the gun, on the servo power lead for each servo, on the power lead for for servo controller, at the relay that switched the gun on, at the power supply for the gun, etc. See the problem? I need someone who understands this stuff to say, "oh, the best place to put the caps would be at _______".

Then there's also the idea Nakarus was talking about:
Quote
make yourself a metal sleeve that fits around the area with the motor, and then tie that into ground.
is it best to place it around the gun motor or around the servo motor instead? is this supposed to function like some sort of half-*** faraday cage?

See the 3 different options for caps and diodes that are applied to the motors in the image below?:

Aren't they there to prevent the same problem I'm experiencing? Which configuration would be most effective?

26  Using Arduino / Project Guidance / Re: airsoft gun motor causing servos to twitch on: March 06, 2013, 12:17:40 pm
The new gun is similarly sized and has a similar weight. If I wanted to use a heavier, larger full metal airsoft gun I would've bought their "Heavy Turret" product instead. The new airsoft gun is just better quality (not that there was anything wrong with the original gun). The new gun is still plastic though. So what do I specifically do to shield it?
27  Using Arduino / Project Guidance / Re: airsoft gun motor causing servos to twitch on: March 06, 2013, 12:00:10 pm
not really. The new airsoft gun has a bigger motor. The solution is simple I would think. We just need the right expert to stumble upon this post. Then he would say, "oh, you need to completely shield the motor by placing blah blah blah in such-n-such way" or "oh, you need to ad caps of this type in this specific configuration". See, that's what I'm hoping for. An actual experienced expert on the topic.
28  Using Arduino / Project Guidance / airsoft gun motor causing servos to twitch on: March 06, 2013, 11:01:25 am
I bought this autonomous airsoft sentry gun from realsentrygun.com http://www.realsentrygun.com/Paintball%20Airsoft%20Turret%20Kit.htm . It works great but I wanted to put a different airsoft gun on it. When I put my own airsoft gun on it and wire it up, the left/right direction servo has like a big twitch when the airsoft gun fires. It didn't do this with the original airsoft gun though. They built it with 'ceramic disk capacitors' going along the wires that power the airsoft gun's motor. When I put my airsoft gun on it, I didn't use them because I didn't understand why I needed to. I've also noticed that the further the airsoft gun's motor is from the servo, the less the servo twitches when the airsoft gun fires. Can anyone explain WHY I need those capacitors, SPECIFICALLY what they do to prevent the interference caused by the airsoft gun's motor, and what I can do to get rid of the interference problem completely?
29  Using Arduino / Project Guidance / Re: Doing a Sentry Gun Project, Need Some Advice on Servos on: February 11, 2013, 09:16:34 am
I've tried both. The one from http://www.realsentrygun.com/ is a lot better IMO. It's more popular and has been around a lot longer. It tracks better. The accuracy is much better. The target filtering is much better. It's a lot less buggy too. Their system has been used by Valve for their portal turret, by The Discovery Channel, and by channel 5 in the UK. This isn't an arduino vs pololu thing, it's just that the sentry project's software is a lot more developed. It's likely because they've been at it a lot longer.
30  Using Arduino / Project Guidance / Re: Doing a Sentry Gun Project, Need Some Advice on Servos on: February 11, 2013, 12:10:51 am
The http://RealSentryGun.com/ works so well that it kinda scares me o_0

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