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1  Using Arduino / Project Guidance / Re: Long-range passive RFID on: March 04, 2014, 05:27:38 pm
Thanks. I'm thinking that 1m might be a bit much to expect at this point. Optimally, I'd like something that people can have in their pockets, and have it read by the system as the walk past. For this, perhaps even 30cm might do the trick.
2  Using Arduino / Project Guidance / Long-range passive RFID on: March 04, 2014, 05:08:42 pm
I'm trying to figure out the best way to implement passive RFID reading over relatively long ranges. (Around a meter)

According to http://en.wikipedia.org/wiki/Radio-frequency_identification#Frequencies, the 13.56Mhz readers can get up to a meter, but I haven't found any readers in that range that spec higher than 10cm.

Is this possible using regular RFID solutions. I am hoping to be able to do this in a relatively small form factor, and preferably with passive tags.
3  Using Arduino / Sensors / Re: Dial that looks like a potentiometer on: April 20, 2013, 03:32:33 pm
That video shows what I'm expecting to happen. On mine, both LEDs blink right when I turn it another tick. By default they're both off.
4  Using Arduino / Sensors / Re: Dial that looks like a potentiometer on: April 19, 2013, 10:52:45 pm
I'm looking at articles on rotary encoders, and I think mine may be a bit different. Instead of the ouputs staying connected between ticks like in , it just blinks very rapidly right at every tick.
5  Using Arduino / Sensors / Dial that looks like a potentiometer on: April 19, 2013, 10:19:54 pm
While salvaging a broken stereo I came across what appeared to be a potentiometer behind the volume knob. The only difference appeared to be that it could turn infinitely in both directions. I hooked it up like a pot, with hot on one side, ground on the other, and an LED on the wiper. I was very surprised to find that the LED would blink every time I moved the knob a tick.

The problem is that the behavior appears to be the same when I move the knob clockwise or counterclockwise, so I don't know how I would actually use it with the arduino. Does anyone have any experience with these and/or know how they work?

Picture of the dial:
6  Using Arduino / Project Guidance / Re: Voltage pulse stimulator for biosensing applications on: June 13, 2011, 05:28:05 pm
The blink program works for the frequency, but the pins on the arduino can only supply 40mv of current. Unless you want to put 12 of the IO pins in parallel, you'll have to use some transistors, capacitors, and the PWM system.
7  Using Arduino / Project Guidance / Re: program stops after disconnecting from computer on: June 13, 2011, 05:23:47 pm
I would recommend 4 1.5 volt batteries. It should provide enough current, and in my opinion 9v batteries are a ripoff anyway.

This probably doesn't apply to many people, but when I used my nxt in conjunction with my arduino, I found that my rechargeable lego battery could power both at once. Also, 6 batteries worked, though it may not be recommended to use 12 volts.
8  Community / Website and Forum / Re: Login form on main page on: February 13, 2011, 10:41:19 pm
Guys,

before we go all crazy smiley I think you deserve an explanation on how the SSO works and why we haven't implemented the feature you request (yet). This doesn't mean we are looking into feasible methods, but for now it is not possible because:

- the SSO (single sign on) system resides in its own separate server protected with a certificate to ensure there is a secure connection and that your usernames and passwords don't fly over the internet unprotected

- the different websites are having their own way to identify users and we make them request a secret token from the SSO server to identify the user and make sure he/she is logged in

- the scenarios you guys suggest imply that, at this point, we should let the passwords fly freely from e.g. the forum into the SSO server and that is a solution we are not willing to implement because of its high risk

In other words, we understand he usability issues mentioned in this topic, but it is nothing we are going to implement now since it would mean putting the whole Arduino website under https, which according to some reports it could slow the server up to 5 times depending on the case. We need to make a lot of performance tests before we can do that.

His is coming from my severely limited knowledge base, but would it be feasible to submit the login information via a javascript that can make a separate connection to the secure server?

Also, many logins don't have https. They use post. Considering the fact that we're not storing out SS #s on here, I think that post would be fine. =)

Again, this is out of my limited knowledge. I hereby release this post into the public domain.  smiley
9  Using Arduino / Project Guidance / Re: [SOLVED] millis() on: February 07, 2011, 05:38:52 pm
Oh. I see. Arduino is cool like that, making the millis perfect.  smiley
10  Using Arduino / Project Guidance / Re: millis() on: February 06, 2011, 11:35:21 pm
Cramming millis() into an unsigned integer means it will go screwy in little over a minute (65.536 seconds to be precise). All the variables relating to millis() must be defined as the unsigned long type.       

This is probably beside the point, but I'm pretty sure that the timer actually counts 1024 milliseconds per real second, so the integer actually overflows after exactly 64 seconds. Again, beside the point, but true.

About the code, pluggy is right. You'll have to define all variables relating to time with the long identifier. If you're crammed for space (Which I doubt you are) you could divide the number of milliseconds by 1000 (Or 1024 to be precise) if you can work with just knowing how many seconds have elapsed.
11  Using Arduino / Motors, Mechanics, and Power / Smooth PWM signal on: February 06, 2011, 10:54:06 pm
Hello, forum! I have been working on a project that lets me debug analog and digital sensors for the NXT robotics system. During the development, I had the need to convert digital to analog signals that could be read by an ADC unit. I found it very difficult to find the information on the subject, and now that I've found it, I thought I might share some informational links for smoothing out PWM signals.

Note, I didn't write these.

Websites:
http://www.datadog.com/pwm_tutorial.pdf
http://www.ehow.com/how_7867398_design-circuit-smooth-pwm-signal.html
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/filcap2.html
http://ww1.microchip.com/downloads/en/AppNotes/00538c.pdf

Here's hoping that others can find the information on this topic more easily than I did.
12  Community / Website and Forum / Re: Login form on main page on: February 06, 2011, 12:30:22 pm
Please could people vote for their preference on the poll? If we get enough votes the team might take notice.
13  Community / Website and Forum / Re: Please exclude old forum from search engines! on: February 05, 2011, 09:42:46 am
Your text says "New Forum:" and then right under that it says "Forum 2005-2010 (read-only)" which would appear to completely negate your theory.
If you check the REAL new forum home page you will see a tiny fraction of those message counts.

Actually, going down into those categories shows that all of the posts were in fact migrated, although they were not sorted. This means that theoretically, if only the new forum were searched it would still get all of the old posts, just on the new forum. Please actually look into what you're talking about before you say it.
14  Community / Website and Forum / Re: Login form on main page on: February 04, 2011, 09:12:09 pm
This would actually be VERY easy to implement.  Just replace the help, login, register thing with a tiny little login form.This doesn't even require a change to the css. (idea 2) Maybe if enough people like it it will be implemented.
15  Community / Website and Forum / Re: Login form on main page on: February 04, 2011, 06:56:29 am
idea2 uses no more space than the current site. It just replaced the help and login links with credential fields.
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