Show Posts
Pages: 1 [2] 3 4 ... 16
16  Community / Bar Sport / Re: Urgent help needed with bar puzzle on: August 22, 2013, 08:41:00 am
I would have to say that the odds change when you know the result of the ash tray that was removed.  Originally, you have a 1 in 3 chance.  Because you know that an ash tray has been removed that has nothing under it, you odds have changed to 50:50.  Think of it this way.  You're sitting at the bar and have the 1:3 chance and so on.  The bar tender removes the one ash tray and it has nothing under it.  You walk away.  Someone else steps up to take your place.  There are two ash trays sitting there.  One is close to him, the other is pushed back a little.  There is no 3rd ash tray because the bar tender took it away.  What are the odds?  2 in 3, right?  WRONG!!! They are 50:50.
17  Community / Bar Sport / Re: Urgent help needed with bar puzzle on: August 13, 2013, 11:15:42 am
I still have to disagree.  The previous conditions have no bearing on the new odds.  The odds are 50:50 because you now only have 2 ashtrays and only 1 of them has the coin under it.  The fact that the bar man will always offer for you to change your selection means that he has no bearing on the odds.  Yes, in the previous test, you had a 1 in 3 chance.  In the current test, you have a 1 in 2 chance.  The removal of the ashtray changes the conditions and starts a new test.  The current test is not dependent on previous odds, unless the bar man turned over an ashtray with the coin.  Since he did not, the odds are now 50:50.  There is nothing counter-intuitive here.  The doubt in your own mind is the problem, not the odds of finding the coin.
18  Community / Bar Sport / Re: Urgent help needed with bar puzzle on: August 12, 2013, 11:28:27 am
You're talking about probabilities only.  Playing the numbers, yes, your probability is much better after all of the other ashtrays have been taken away.  It doesn't matter who else knows where the coin is.  This is just added to try to embellish the story.  If the person choosing doesn't know the location of the coin, the odds are still 50:50.  Abandoning the first ashtray and selecting the other does nothing to the odds.  They're still 50:50.

After removing the previous number of ashtrays, the new conditions are these: you have 2 ashtrays, there is a coin under one of the ashtrays.  You have one ashtray under your hand and the other is not.  The location of the ashtrays has no bearing on the odds.  They are still 50:50.  The current odds are not dependent on previous odds.
19  Using Arduino / Sensors / Re: reading pushbutton. only if HIGH for 5 sec or more, start next routine on: August 07, 2013, 06:59:02 am
I did something similar to this once.  I had a routine that would check to see if a button is being held.  If it was, a counter would decrement during each cycle of the loop.  Once the counter reached zero, the button behavior was different.

I wanted to do what you see with a lot of clocks.  When you push a button and hold it, it counts slowly at first, then very quickly after the button has been held for a few seconds.  Worked great.
20  Community / Bar Sport / Re: What are people's "Day Jobs" on here? on: July 25, 2013, 11:10:06 am
I provide technical support to our distributors for residential thermostats we manufacture.  I work for a large HVAC manufacturer in the USA.
21  Topics / Home Automation and Networked Objects / Re: Arduino + Raspberry Pi Thermostat and Zone Control -- Need Guidance on: July 23, 2013, 12:02:39 pm
>>My Understanding of Zoning

>>  Each room in a house is a "Zone" --This isn't necessarily true.  Ideally, yes, it's nice to have each room as its own zone, but
>>  in practice, you may need to combine some rooms to make zones.  See reasons below.

>>  Each zone is 'Independently' controlled by temperature sensor.  Yes.
>>  The Zone's HVAC Registers are opened or closed (Partially in some cases) to control room temperature If you can control
>>  the blower CFM, yes, this works well, but in a typical split or packaged system, you should only go full open or full closed and
>>  not try modulating the dampers.


You should be careful how you implement this.  Are you using a split system, packaged system, ductless split, window unit?  With split systems and packaged systems, airflow is very important.  The system wants to run at a specific airflow.  If you choke off too much of your duct system, you can't move enough air.  For gas furnaces, this can burn up a heat exchanger == lots of $$$.  Likewise, in cooling, you can prevent the refrigerant from boiling off in the evaporator coil, which can mean that liquid refrigerant is being circulated back to your compressor.  We all know that you can't compress a liquid, so that causes damage to your cooling system.  Again, lots of $$$.

Zoning is a great way to ensure you have maximum comfort, but it is a very complicated animal.  Be careful and have fun.
22  Topics / Home Automation and Networked Objects / Re: Help choosing the right wireless module on: July 02, 2013, 09:44:47 am
I'm also getting interested in wireless.  Does anyone in the community have some sort of chart or side-by-side comparison with some strengths/weaknesses for beginners such as myself?  I've been trying to do some research, but I'm still having some difficulty in how to choose a suitable solution.
23  Community / Bar Sport / Re: Keep weapons off Arduino forum and website on: June 10, 2013, 11:27:57 am
How do you define a weapon?  Is a car a weapon?  Are words weapons?  Are electronics weapons?  It depends on how the particular object is being used.  That, then, is also dependent on the intent of the person wielding it.  I don't think it's so easy to just say that this thing is a weapon and that one isn't.
24  Community / Bar Sport / Re: Flying with Arduino on: April 28, 2013, 05:00:45 pm
@Crossroads

The limit is a spoof on the 10 round limit to magazines in guns.  NY state just passed a law limiting guns to magazines of less than 10 rounds.
25  Community / Bar Sport / Re: How do you misuse sticky tape? on: February 04, 2013, 04:27:48 pm
Maybe they don't want you to mistake misuse it for toilet paper!
26  Topics / Device Hacking / Re: motion detector hack? on: February 03, 2013, 09:45:03 pm
I just left my motion sensor in-circuit and soldered a wire to the appropriate terminal on the opamp output.  It was easier for me to use their circuit rather than redesign the whole circuit.  As long as you know the proper input voltage, you can use their circuit and repurpose the motion sensor for yourself.  Once you've done some experimenting, you can buy one from radio shack or online for around $10 US.  Sounds like you're on the right track.  Have fun.
27  Using Arduino / Sensors / Re: What can measure how much propane i have in two 20lb tanks? on: January 29, 2013, 11:43:47 am
Most of those cameras can see infrared, so if you didn't want a light turning on to bother you when you're trying to go to sleep, you could use an IR LED as the light source.  May need to check that it will properly illuminate the target.  As Nick said, you could just turn it on intermittently, so you don't use too much power.
28  Topics / Device Hacking / Re: motion detector hack? on: January 27, 2013, 08:36:30 pm
So I'm wondering if you've had any luck with your project.  Have you been able to locate the output pin from the final stage of the amplifier?  Hopefully, you're on your way to using this motion sensor for your own purpose.  I look forward to hearing about it.
29  Topics / Device Hacking / Re: motion detector hack? on: January 24, 2013, 03:02:21 pm
Looks like you're not seeing any action from the community on this.  I have played with some motion sensors that I hacked from air fresheners.  I can't speak to the one that you're describing, but I can tell you that the LM339 is a quad op-amp.  It is used to amplify the output from the sensor up to 5VDC.  You should be able to verify this by finding the appropriate output pin on the op-amp with a volt meter.  You'll have to follow the circuit traces and do some detective work for this.  The output pin would pulse high for about a half-second when the sensor "sees" motion.  Just check each one until you find the one that outputs the highest voltage.  You could solder a wire to that circuit trace and feed it to an Arduino as an input for your new project.

LM339 datasheet can be found here: http://datasheetcatalog.com/datasheets_pdf/L/M/3/3/LM339.shtml
30  Topics / Home Automation and Networked Objects / Re: Project iCamper on: January 22, 2013, 07:56:30 am
@TrailerTrash
If you're camping at an electric site, use electric heaters.  You're paying for it anyway, why use up all of your propane?  We use the 30 amp and plug one heater to a receptacle inside.  We run an extension cord to the 20 amp plug outside and bring it inside for the 2nd heater on really cold nights.  We have a Flagstaff popup camper and have camped down to 35 deg F and stayed very comfy.   Another idea is to use electric blankets at night.  Happy camping.  I do like your electronics ideas, by the way.  Looks like a fun project.  May I suggest using RGB LEDs for some mood lighting?
Pages: 1 [2] 3 4 ... 16