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181  Using Arduino / Project Guidance / Re: Arduino Water Controller on: May 02, 2012, 01:19:40 pm
You aught to make sure that the voltage drop is too much before you try anything else. If it is, it sounds like you have 24 V DC to work with, you could feed the signal from the Arduino  through a transistor hooked up to the 24 volt source. That should give you more than enough strength to drive a relay.
182  Using Arduino / Interfacing w/ Software on the Computer / Re: VB to send command to arduino on: April 28, 2012, 09:05:31 pm
This is the VB6 code I use to find the com port the Arduino is on:

For n = 1 To 16
  If MSComm1.PortOpen = True Then MSComm1.PortOpen = False
   On Error Resume Next
   MSComm1.CommPort = n
   On Error Resume Next
   MSComm1.InputLen = 0
   MSComm1.PortOpen = True
   If MSComm1.CommID > 0 Then
     For i = 1 To 100  'keep trying
      str = ""
      str = MSComm1.Input

      If InStr(str, "< ") > 0 And InStr(str, ">") > 0 Then GoTo jump:

     ' these are the chars I use to bracket the output from the Arduino
     ' you can use anything you want
     ' the reason I do this is so the VB can tell the Arduino port
     'from other active ports otherwise the code
     ' will just pick the first one open
      Sleep 50                                                                                       
     Next i
  End If
Next n
If MSComm1.PortOpen = False Then MsgBox "Controller Not functioning , Please check USB connection", vbCritical, "": ComFail = True: Exit Sub

183  Using Arduino / General Electronics / Re: Controlling Resistance Heaters on: April 28, 2012, 08:13:39 pm
A simple solution would be using a 555 timer to adjust the "duty cycle" of the resistance. The 555 timer would cycle the resistance element on and off through the solid state relay previously mentioned.You could use a potentiometer to adjust the duty cycle.  It would be nice to have some feedback  to tell what the temperature is, but thermocouples are expensive.  If you don't have feedback, then the 555 is just as good as the Arduino and not nearly as expensive. I have used this simple circuit to control a ceramics kiln, and it worked just fine. The grunt work come finding what duty cycle corresponds to what actual temperature... have fun
184  Using Arduino / General Electronics / Re: Arduino measuring its own power supply on: April 28, 2012, 07:54:50 pm
Use a 10K trim pot for the 5K resistor, that way you can fine tune the circuit to get exactly the voltage you want.
185  Using Arduino / General Electronics / Re: Can you get a negative and positive voltage out of the same source? on: April 28, 2012, 07:37:05 pm
What is your application? if you need +9V and -9V for say an op-amp you can get a 9 volt center tap transformer and a couple of diodes and capacitors to do the trick.

If this doesn't make sense to you and you are completely green, you may have to back track and learn a little basic electronics to get very far with your project.
186  Community / Exhibition / Gallery / Re: Egg Painting Robot on: April 11, 2012, 08:53:19 pm
A little beyond my capabilities for now jwatte, but also very impressive. Thanks.
187  Community / Exhibition / Gallery / Re: Egg Painting Robot on: April 10, 2012, 06:53:09 pm
Where do you get your gears???
188  Community / Exhibition / Gallery / Re: LED photostrobe Alpha test on: April 10, 2012, 06:50:19 pm
Looks Good... Drive um up there! ... 150, 200, 300%... LED's are cheap, and getting cheaper all the time.
As long as the pulses give time between for thermal dissipation, you can probably pull it off. All the LED's I have burned out, took at least a second to self destruct, but that was continuous current +200%.
189  Using Arduino / Motors, Mechanics, and Power / Re: New Libray for L298N on: April 10, 2012, 06:32:14 pm
Thanks sbright33 I can use this in a sun tracker project I am working on
190  General Category / General Discussion / Re: Long term reliability on: April 08, 2012, 07:52:52 pm
If you are having problems with rough environments, maybe you should just try and "pot the whole board"( minus the connectors you will use)... paint it with epoxy resin. That should seal it and still allow for heat transfer, if that is any kind of issue.

191  General Category / General Discussion / Re: Where to buy from China? on: April 08, 2012, 07:44:31 pm
If you are adventuresome, you might try goodluckbuy, or futurlec. they are bot Chinese outfits and take forever to get your parts to you. They get crappy reviews because of this, but they have lots of stuff on the cheap, and I have not had any problem with them. I got a cheap Arduino due clone from goodluckbuy that was  a better board than the true one. it was only around $18 and the shipping is free.

Take a look. there is a lot of stuff that's lots of fun.
192  Topics / Science and Measurement / Re: Pulse generator? on: April 07, 2012, 04:26:57 pm
Here is a script I use to do pulse width modulation for a electroplating tank
the pulse width is determined by a potentiometer to the analog in.

You could just as well control it with input from the USB port. There are lots of sample of how to do this in the Forum

// set pin numbers:
 int platepin = 2;
 int plateGrnd =3;
 int unplatepin =4;
 int unplateGrnd=5;
 int DutyHi;
 int DutyLo;   
float DutyRatio;
void setup() {
  // set the digital pin as output:
  pinMode(13, OUTPUT); 
  pinMode(2, OUTPUT);
  pinMode(3,OUTPUT); // go low when 6 is high
  pinMode(4, OUTPUT); 
  pinMode(5, OUTPUT);// go low when 7 is high
void Sequence_plating()
  delay(10 *DutyHi/1023);
  digitalWrite(platepin, LOW);
  digitalWrite(unplatepin, HIGH);

void Get_Ratio()
    DutyHi = analogRead(0);
    DutyLo = 1023; //analogRead(1);
    DutyRatio = (DutyHi+1/(DutyLo+1)); // 1023/0 max
    if ( DutyHi <= 700) // warn that duty cycle is approching unplating

void loop()
193  Topics / Science and Measurement / Re: High Resolution Thermocouple and Data Log on: April 07, 2012, 04:10:52 pm
I think you will have a hard time finding a thermocouple element small enough in thermal mass to respond to changes as quickly as you wish to measure. You may well end up with just average while the thermocouple undergoes a slower response.
194  Using Arduino / LEDs and Multiplexing / Re: Multiple LED strings on: March 31, 2012, 05:23:31 pm
the 2N2222A transistors should work fine. You need them to supply enough current to drive all them lights! If you tried to drive them just with the pin outs of the Arduino, then you wouldn't have enough current.
195  Using Arduino / Project Guidance / Re: Solar Tracker Project on: March 28, 2012, 06:15:51 pm
The "down n dirty" way I use is with  photo resisters. Normalize the output, build a jig that has them looking up with about 15 degrees between them  . hook them up to  analog 0 and 1. Read the output every so often( whatever you want) ant based on the delta V between them drive a stepper motor in the direction  of the brightest light  ( hopefully the sun).

You can program a min brightness so that the whole thing rests during the night. Since you are going to be tracking from East to West, you can either count the steps and when the brightness threshold drops below minimum, then step back East that number of steps and be ready for the next day. You can also just leave things as they are and the tracker will track back incrementally the next day.

This eliminates precise stepper calculations since the tracker stops when the photo resistors both bracket the sun.
I,ve done this, it works, but you have to get creative in lensing in the sun as it travels far to the North during the summer and passes overhead of the detector. I used an arched clear plastic lens with light  baffles around the photo resisters so that a narrow strip of sky was presents with an arc of about 60 degrees N-S

Have Fun

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