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841  Using Arduino / General Electronics / Re: PWM & audio (tone or .wav) has noise? on: June 09, 2013, 11:40:20 pm
Quote
for 1) you could add very small capacitors to the signal to slow down the edges, and increase decoupling on the LED supply.



1 kHz PWM,  the base frequency is 1 kHz, then 2nd harmonic is 2 kHz ... 10th harmonic is 10 kHz...20th harmonic is 20 kHz. they are all in humans hearing range !  add very small capacitors will be no help.
842  Using Arduino / Networking, Protocols, and Devices / Re: Android + Arduino issues (over USB) on: June 09, 2013, 11:17:04 pm
How about try different Arduino ?

Duemilanove use an FTDI USB-serial chip

Uno use CDC-ACM serial-over-USB

Leonardo use USB's Connected Device Class CDC
843  Using Arduino / Networking, Protocols, and Devices / Re: How to automatically disconnect network? on: June 09, 2013, 11:02:22 pm
do not forget OP ask automatically/schedule function.
844  Using Arduino / Networking, Protocols, and Devices / Re: Choice of wireless module on: June 09, 2013, 11:00:31 pm
I have hard time to connect high transmission data rate with color sensor.
Try harder then.
There are a lot of colour to frequency sensors and the OP might be trying to send the output frequency.

maybe  you could show us how to send output frequency of color sensor directly to PC via X Bee or Bluetooth.  smiley-wink
845  Using Arduino / General Electronics / Re: Peltier based aquarium cooler/heater? on: June 09, 2013, 09:25:14 pm
http://forum.arduino.cc/index.php?topic=169717.msg1262798#msg1262798

Plan B ~ Plan F.
846  Using Arduino / Networking, Protocols, and Devices / Re: Android + Arduino issues (over USB) on: June 09, 2013, 06:56:21 am
Quote
The HTC Magic phone is quite an old model of Android phones, effectively it’s the second generation after the original G1 and was the first officially available Android phone in New Zealand. Whilst I have loaded the last stable version of Cynogenmod released for it onto the phone, it’s only Android 2.2 and doesn’t feature the Android USB Accessory API support, so there was no point getting something like the USBDroid model.

http://www.jethrocarr.com/2012/07/22/android-via-serial-to-arduino/

Could you upgrade Android OS at HTC Desire?

BTW, HTC Desire default OS is Android 2.3.x.
847  Using Arduino / General Electronics / Re: PWM & audio (tone or .wav) has noise? on: June 09, 2013, 12:18:01 am
Plan A;-

Noise cancellation, basic pick up out of phase PWM signal feed into Waveshield to cancel PWM. YMMV

Plan B;-

Move Adafruit Waveshield into second Arduino, and power second Arduino with second power supply if you could. connect Arduinos with opto-isolators.

Plan C;-

Use linear LED driver to dim the LED, now frequency is 0 Hz (DC) and out of hearing range.

The 3 key methods;

  • cancellation.
  • isolate, isolate input or power supply.
  • make frequency out of range, either lower or higher than 20 Hz to 20 kHz.


848  Using Arduino / General Electronics / Re: Building a high voltage servo ~ h-bridge help? on: June 08, 2013, 11:03:55 pm
http://forum.arduino.cc/index.php?topic=169717.msg1262798#msg1262798

Plan A ~ Plan F.

BTW, high voltage servo means voltage is few hundred volts and up to thousands.
849  Using Arduino / Networking, Protocols, and Devices / Re: Choice of wireless module on: June 08, 2013, 10:55:10 pm
I have hard time to connect high transmission data rate with color sensor.

What type color sensor?

What type color object you try to measure?
850  Using Arduino / Networking, Protocols, and Devices / Re: rf-switch and 315mhz transmitter is a no go? on: June 08, 2013, 10:49:03 pm


There are four buttons on the remote control, and respectively correspond to the four data bits to the receiving board output pin D0, D1, D2, and D3 of. Press the buttons transmit signals, the corresponding data bit is output high.

first, test pair without Arduino, connect 5 v power, press the button 0~3, receiver's D0~D3 should read high.

second, connect it with Arduino, use digitalRead to get data, and no famous library needed.
851  Using Arduino / Networking, Protocols, and Devices / Re: How to automatically disconnect network? on: June 08, 2013, 10:25:56 pm
Plan B;-

Set up A (scheduled) honey pot. A honey pot is a computer system on the Internet that is expressly set up to attract and "trap" people who attempt to penetrate other people's computer systems. (This includes the hacker, cracker, script kiddy, and un-want supplier.)  Now your supplier is happy, and so are you.
852  Using Arduino / Networking, Protocols, and Devices / Re: How to automatically disconnect network? on: June 08, 2013, 10:23:24 pm
Plan A;-

Prevent unwanted connections with a firewall, firewall could be corp's or cheap Linux base router with firewall support.  This is logic connection control. Using Linux' s cron (schedule) service to set up schedule.
853  Using Arduino / Motors, Mechanics, and Power / Re: motor control L293d on: June 07, 2013, 10:45:45 pm
Plan H;-

BD6212, ROHM Semiconductor

Operating Voltage: 3 – 5.5 V
Output current: 2A
RDS(on): 0.5 Ω

http://rohmfs.rohm.com/en/products/databook/datasheet/ic/motor/dc/bd621x-e.pdf

BD6212HFP-TR, $4.11, Digikey
   
http://letsmakerobots.com/node/31103
854  Using Arduino / Project Guidance / Re: High Current Appliances Switching (Airconditioner) Help on: June 07, 2013, 08:17:46 am
Hi everyone. I need some expert advice smiley I have some experiences in microcontrollers and robotics so the software and hardware parts aren't really problems provided devices used don't require high current. I'm currently working on a new project that switches appliances. I've done everything nicely but one. Since I don't have any experience in switching high current appliances such as an airconditioner, I'm kind of paranoid to try the real thing even if I have the theoritical calculations. I'm currently using an 8 channel relay with a maximum of 10A for the relays. Is this safe enough to switch a...let's say a 1.5 hp airconditioner? Or do I need another kind of relay? In this kind of scenario, what would be the best thing to do? If the relays I currently have aren't enough, is there another option that I can make use of this module? Like connecting these to another kind of higher current relay? Thank you everyone. Any advice would greatly be appreciated smiley

Why not use AC building switch?  setup Arduino as remote control.

http://arduinotronics.blogspot.it/2012/11/arduino-ir-receiver-part-2.html
855  Using Arduino / Motors, Mechanics, and Power / Re: Advice seeked to find a LiPo cell with short length (< 7 cm) on: June 07, 2013, 07:20:02 am
@sonnyyu: as indicated in my first message, my reason to go to 7.4V is that I do also want to provide power to a 5V Arduino Pro Mini (I know there are 3.3V models but I want the 16MHz version).

Use 3.7 v to 5 v dc-dc converter. It is very standard these day and it have good efficiency ( >95%) and cheap. Anyway all we care is W·h, use one or two cell doesn't matter for final number.  Two cell might increase complication of battery management circuit ( balancing, individual cell protection...) .

Apple use 3.7 V battery to power Ipad, You can not power Arduino Pro Mini with 3.7v ?

iPad 2 Battery Capacity:  6583mAh ~3.7v ~24WattHours
iPad (3rd Generation): 11560mAh ~3.7v ~42WattHours
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