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31  Using Arduino / Project Guidance / Re: Using External ADC's on: July 14, 2014, 06:14:39 pm
The ADS1115 is a very nice ADC/MUX that can be configured to switch between 4 single ended analog inputs (or 2 channels of differential inputs). Also the chip has a address pin that can be strapped high or low to gain a second I2C address, so two of these devices can share the two I2C pins (20,21) and handle reading up to 8 analog input signals. The Adafruit folks have a nice arduino library to make using this device pretty simple.

32  Community / Bar Sport / Re: The Cracked Pot on: July 14, 2014, 03:17:54 pm
At least the cracked pot offers variable resistance...

You reminded me that I had an intro physics problem something like that. It's a tower with hole on the side. Calculate something about that hole and water flow. Variable resistance, not sure, but variable water speed, yes.

Flow rate dependent on the depth of water in the tank?


Yes, depth of water (head pressure) is equal to voltage. Crack in pot is equal to resistance (fixed value). Leak rate is equal to current flow and varies with water height. So Ohm's law applies.

33  Using Arduino / Project Guidance / Re: Driving multiple Solid State Relay on: July 14, 2014, 10:17:16 am
There are some DC SSRs that do work with pwm like the power-io HDD-xxxxx SSRs but you will only find that in DC

 There are some AC SSRs that can do some form of slower PWM often called phase controlled. However the PWM switching speed must be at the line frequency speed not the higher speed that the arduino PWM uses, and one must have a external means of detecting the AC zero crossing for proper timing.

 Standard AC SSR only turn on and off it's output at AC zero crossing (8.33 msec @ 60 Hz) where as the 'phase controlled' AC SSRs allows turning on the device at any time in the AC waveform, but can only turn off the SSR at zero crossing like the standard ones.


34  Using Arduino / Sensors / Re: How can I conect a 4-20 mA sensor with external electrical supply on: July 14, 2014, 09:55:49 am
The typical method is to wire a precision 250 ohm resistor from the sensor 4-20ma output pin and then to sensor ground. Add a ground wire from the sensor ground pin to a arduino ground pin. And then wire from the sensor side of the resistor to a arduino analog input pin. At the sensor's maximum 20 ma output the resistor will 'see' +5vdc dropped across it, suitable for the arduino analog input pin. At the sensors minimum 4 ma output the analog input pin will 'see' +1 vdc. 

 
35  Using Arduino / Project Guidance / Re: Driving multiple Solid State Relay on: July 14, 2014, 09:46:54 am
Yes, direct control from on arduino output pin will work. And yes, it will not do PWM output, just on and off control.

36  Using Arduino / Microcontrollers / Re: New 1284P format - 1284OnTop, Bobweeny? on: July 12, 2014, 11:19:23 pm
Nice, another winner.

 Except what's with the reset switch mounted under the chip, how useful will that be?  smiley-wink

37  Using Arduino / Project Guidance / Re: Momentary connection between two wires on: July 12, 2014, 11:08:15 pm
Thank you very much for the help here.  I'd like to further my understanding on this topic a little bit more.  Can you go into some more detail on the polarity and current direction with transistors and Arduino?

Thank you!

 I cannot think of a easy way to condense basic electronic and semiconductor theory into a simple posting response. There is a way to learn all that but not via an internet forum. Start reading some basic electronic theory and if a given topic or subject isn't clear ask a specific question here.

38  Topics / Robotics / Re: Why would it not accept DC jack as power supply on: July 12, 2014, 04:02:35 pm
As simple test will prove to yourself that a 9 volt transistor battery won't cut it for you project. Just take you multimeter and measure voltage between the Vin pin and ground when trying to power using the battery. Tell us what voltage you measure.

39  Using Arduino / Installation & Troubleshooting / Re: No version of Arduino will start on Windows 8.1 on: July 12, 2014, 03:36:05 pm
I had this problem for awhile too, and I think I know your problem.

Check the file location of the software. Chances are, it is in the "Documents" folder. Drag it out of the folder and into the "Downloads" Folder. I'm guessing you were using windows 7 before, and it is able to run the software when it is in the "Documents" Folder. If this doesn't work, or it was in the downloads folder already, please let me know.

Well I don't know what his problem might be, but I've been running arduino on a win 8.1/64 laptop with the IDE folder located in my Documents folder with no problem. I do run as administrator so he might check what access level he is running at.

40  Using Arduino / Microcontrollers / Re: Arduino UNO as ISP doesn't work on: July 11, 2014, 06:17:31 pm
The essayist way to program those is to swap chips its super easy and you load it just like the uno then take it out pop it in your project and done smiley

I like the sounds of this method. Once flashed with the bootloader and your sketch, will it then require an external oscillator or will the internal be used? 

It will require an external crystal or ceramic resonator as when the bootloader is burned into the chip it also burns the fuse bytes which set up what clock source to use.

 If internal, does it require calibration?  I'm trying to time some blinky project pretty specifically, and it didn't work out for me so well with the ATTiny85 as the internal oscillator required calibration, which apparently is not something I'm capable of.
41  Using Arduino / Audio / Re: Need help determining which speaker is louder on: July 11, 2014, 06:07:47 pm
Well one is rated at 2 watts max and the  other at 0.2 watts max power consumption. Neither gives what it's audio output is at their rated max power (SPL rating), but I would suspect the first can be driven louder then the second based on the very limited information given in the product descriptions.

42  Using Arduino / Microcontrollers / Re: ATMEGA 1284 - Definative Bootloader Solution.... on: July 11, 2014, 12:42:50 pm
From what I can see its a whole heap of work to go down the bootloader route....
Is it easier to just program the 1284 via ISP ??


Not really. Once a bootloader is installed it works pretty much automatically with the arduino IDE when doing normal uploading. There are two parts of that process, first the hardware that connects the USB serial converter chips DTR or RTS signal via a series capacitor that triggers a auto-reset on the 1284 which starts the bootloader and then the actual uploading of the sketch code via serial data.

 But programming via the arduino IDE's upload using programmer option under the file menu is pretty simple requiring no USB serial converter nor auto-reset circuit, but does require a 'hardware programmer' which can be one of six different kinds supported by the Arduino IDE programmer selection menu.

43  Using Arduino / Project Guidance / Re: triple pole triple throw relay on: July 11, 2014, 10:31:43 am
You need to use two relays. First a DPST where the common goes to the motor and the NC to CW and NO to CCW. The second SPST relay just switches the motor common. In your arduino you would use two digital output pins each using a switching transistor to control each relay coil. In your software one output is motor on/off and the other output is rotation direction. It would not be possible to switch on CW and CCW at the same time in error as it's a single digital output.

44  Using Arduino / General Electronics / Re: Reading voltage - Product already exists?? on: July 10, 2014, 06:09:38 pm
I think our legs are being pulled.  smiley-wink
45  Using Arduino / Installation & Troubleshooting / Re: Arduino IDE Beta 1.5.x ? on: July 10, 2014, 02:00:48 pm
If you are using a 8 bit AVR arduino board then 1.0.5r2 is the current stable release. If you are using a 32 bit arduino board then `1.5.x is what you must run and it is still in beta. Eventually they will most likely be merged into a single stable release.

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