Show Posts
Pages: [1] 2 3 ... 192
1  Using Arduino / Programming Questions / Re: Multiplexer Problem with arduino on: July 25, 2014, 05:26:12 am
Ground Vee pin7. And do read the  the data sheet.. Carefully.

2  Using Arduino / General Electronics / Re: 110V detection on: July 22, 2014, 06:36:50 pm
It might be simpler to use a NE2H (W 100K series current limiting resistor) across the wires going to the load and an LDR to sense when the light is "On". You will need to shield the LDR from incident light and heat shrink tubing does well for this.  Alternately the LDR / neon light combination could be potted in an opaque potting material. The reasoning for the neon lights that fast, high energy transients will destroy semiconductor light emitters (Led's) quickly... I made that mistake many years ago when I made a sensor circuit to determine when any of 10 relays were energized from another mechanical controller by measuring the relay coil voltage... needless to say the opto-isolators were destroyed in the field as soon as the system was powered up and activated... I might add that I had tranzorbs across the relay coils and a zener clamp across the LED's.. were useless in fixing the problem... Being the engineer on that project... It was my duty to find and fix the issues. and the neon light/LDR combination was the answer that worked every time in the field. I might add that some of the relay coils were grounded and some were connected to 120/240 Vac and grounded to activate, which precluded  the use of a very wide return point which would have greatly facilitated filtering or clipping the transients... This was for a center pivot irrigation controller that had to report all conditions, water flow, position, number of rotations , variable for the individual crop being grown and to control the "End Fire sprinkler valve that irrigated the corners of a quarter section plot of land..

3  Using Arduino / Programming Questions / Re: [SOLVED] Shuffle a char array? on: July 22, 2014, 03:16:12 pm

4  Using Arduino / Programming Questions / Re: My EEPROM data kept resetting =( on: July 21, 2014, 10:27:02 pm
Your schematic shows an Arduino? pin? that is grounded directly...
Do you have the board wired as per the drawing? or is the switch symbol incorrect?
@ Guix,  Which pin on an Arduino is PIC?

5  Using Arduino / Networking, Protocols, and Devices / Re: SD card + nRF24L01 SPI conflict on: July 20, 2014, 12:41:23 pm
Try 47 - 100 uF. The 3.3 V regulator on most Arduino devices is only good for more than 50 mA.
The larger filter cap helps to smooth the power to the radio and is the most common failing of the Uno or Mega boards 3.3 v power supply.

6  Using Arduino / Networking, Protocols, and Devices / Re: My NMEA GPS parsing library. on: July 20, 2014, 05:59:17 am
And tjnygps+ is a whole different thing entirely.
I''ve used both and tiny+  is the easiest of all

7  Using Arduino / Microcontrollers / Re: How establish communication between Attiny and Arduino One? on: July 17, 2014, 06:09:54 pm
The I2C bus does have some length and loading issues..About 20 cm and a max of about 400 pF. It was never intended for wired use as I2C means Intra Integrated Circuit.. On one board, not a meter of wire per leg. A basic rule of thumb for I2C is that, more devices on one bus require lower value pull-downs to minimize the effects of bus loading.
RS485 is much better suited for this purpose as it is a long distance multi-drop communications protocol and MAX485's are inexpensive and easy to use. RS485 breakout boards are inexpensive on FleaBay..

Edit for clarity.. Doc
8  Using Arduino / Microcontrollers / Re: Please help. 3.3V usage. on: July 13, 2014, 03:55:54 am
@ Paul... +1

9  Using Arduino / Programming Questions / Re: Void Setup on: July 12, 2014, 03:55:21 pm
A Good book on C++ Might help... Is Free Too...
This might help.. What value is setup() supposed to return and to where... 
Setup() is called only once.
Void indicated that setup returns nothing. is one of Many "Go To" resources available for learning the language.

10  Using Arduino / Microcontrollers / Re: Microchip crystal errata? on: July 10, 2014, 08:02:08 pm
Well, they are 'usually' good with free samples... Spreading useless technology... This was the reason I quit using Microchip for anything important...

11  Using Arduino / Programming Questions / Re: Developing with c++ on: July 03, 2014, 02:02:08 pm
The "basic" Arduino "language" ic C++... some electronics knowledge would go a long way in helping your project towards fruition.
Sometimes it is most difficult to write code to repair defective circuitry... , So  a basic knowledge of electronics would be  very useful.. In my working days we called fixing bad circuitry...tuning the bread slightly reducing the uC clock crystal loading cap values to compensate for the extra stray capacitance of the bread board. There are some applications I've done where the proc  doubled as the reference clock for a PLL ... Another area where a good base in electronics or a class a engineering techie is a must..

12  Community / Bar Sport / Re: Question about FAQ and Open Hardware. on: June 28, 2014, 05:29:57 am
When I was young... the only "Solid State devices were lead sulphide or Galena "Cat whisker" detectors for AM broadcast band "Crystal Radio's", Some selenium and copper oxide rectifiers were just coming in vogue as replacements for Tungar or mercury vapor rectifiers..
 This was in 1956 I was 10 years old then... How old were You?

13  Using Arduino / Microcontrollers / Re: Is this "too good to be true"? on: June 28, 2014, 04:09:06 am
Provided you are in possession of the proper SMT rework tools... last time I checked, A basic hot air/soldering station was upwards of $70.00... and a 328P-AU was $2.00 to $4.00, adding a half an hour labor (I don't recover used parts without VERY GOOD reason as they tend to be less than reliable... and the aggregate cost for a used part can easily exceed the cost of a new one....
Easier to use an X-Acto knife and cut the IC pins, wipe them from the board with a hot iron and "Do It RIGHT"..
If a board is only suitable for it's components for "Parts Stock", there is a reason why...
I choose to buy new components when it comes to SMT devices... In 40 years of design work I've never found it advisable to use pull off's from SMT boards... Always a question about whether the part is actually OK and I'd much rather replace an expensive IC than wonder if it was OK. Frequently they weren't... It was usually the more expensive parts that cost me the most time...

14  Using Arduino / Microcontrollers / Re: Arduino Zero on: June 27, 2014, 05:18:18 pm
Did you read ALL the data sheet?? I don't think so...
The second line of the data sheet Summary states:
Operating Voltage   3.3V
this means that any input unless otherwise stated... IS a 3.3V input, Exceed the Vcc limits and you will cause an input protection diode connected to Vcc (3.3Volts) will limit the input to 3.3V + the protection diode drop or about 3.8 to 3.9V. If you need to measure voltages greater than Vcc (3.3V) you will need to scale it... to accurately measure it.
This is most commonly done with a resistive voltage divider or an Op-Amp... The resistive divider is simple and accurate.
The Op-Amp is a great deal more accurate and can handle negative input swings that the resistive divider cannot, easily or accurately deal with, again because of the input protection diodes that clamp any I/O to Vcc/ground... +/- the diode drop..

15  Using Arduino / Microcontrollers / Re: Fake Easydriver? on: June 27, 2014, 04:54:50 pm
What is the stall current of the motor?... That smoked IC Motor Driver (A3967) [data sheet attached], to my sore, tired OLD eyes looks like it either was used to power a load (motor) that draws more than 750 mA (See attached data sheet) or had a load greater than 5w...
The "Stall Current can" be 3 X 5 times the run current and the total motor current is a function of the load on the motor as well as the supply voltage for the motor
For example a motor rated at 12 VDC with a  750 mA load represents  (P(Power) = E(voltage) X I (current) for (P = 12V X .75A) or 9 watts..... I used 12V to illustrate just how easy it is to exceed the device MAXIMUM ratings.
Since you didn't see fit to read the sticky note about [How to use this forum - please read.],  located at At the top of the page...
and you did 't post the schematic or the operating voltage of the motor...  or the data sheet for that matter which clearly shows a 5 Watt MAX power dissipation for the A3967 on page two, the chart at the bottom is VERY easy to read...
The difference in the power input bypass capacitor value and operating voltage are really to your benefit and not an error or something to cause your issues.
You also failed to indicate the sense resistor values... The Sense Resistor is used to keep the driver within safe limits by "Sensing" the motor current required and limiting the motor current to "Safe" limits for the driver IC.

Pages: [1] 2 3 ... 192