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181  Using Arduino / Programming Questions / Re: Chicken Coop - LCD + 2 Fans + 2 Lights + RTC + DHT11 + Stepper on: December 09, 2012, 07:41:38 am
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This issue seem to be above your level of competency.
R i i i i i i g h t! - Scotty
182  Using Arduino / Motors, Mechanics, and Power / Re: Rail to move a camera at precise speed? (0.25 meters per second at 1mm accuracy) on: November 30, 2012, 10:24:38 am
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I can do this!  I can send you a picture of the slider.  The coding is easy.  After you see what I've built, you can tell me how much this setup is worth to you.

I'm interested in what you have done. Would you post pictures please? - Scotty
183  Using Arduino / Motors, Mechanics, and Power / Re: DC motor with very high torque on: November 30, 2012, 10:16:13 am
100kg. Is that correct? - Scotty
184  Using Arduino / Programming Questions / Re: second tcrt5000 reflective sensor will not trigger reverse relay. on: November 30, 2012, 08:31:38 am
Ouch! Won't this have the potential to be a dead short if both sensors detect a reflective media at the same time thus energizing both the forward and reverse relays at the same time? I think some code is needed to prevent that scenario. Also, relays are mechanical and are not instantaneous. One relay will be slower than the other to operate; therefore one may still have it's contacts closed (although the coil is no longer energized) when the other relay closes it's contacts , i.e., same same dead short scenario. Some delay is needed to ensure the previously energized relay has opened it's contacts before energizing the other relay.

- Scotty
185  Using Arduino / Project Guidance / Re: Solenoid & Stepper Motor power problem. PROTECT ME! on: November 29, 2012, 04:38:10 pm
I wouldn't call it a power loss; that suggests not having enough power. It would be a power waste in that the differential between input an output of a regulator is burned off as heat. e.g. for the 7812 the input is 19, the output 12 so 7 volts is 'burned off'. How much power is wasted can be determined by multiplying the voltage differential by the current going through the device. If your not energizing the solenoid ALOT, I wouldn't worry about it unless your running off a battery or battery pack; and I doubt that since 19 v would be an uncommon battery voltage. Same with the 7805. With your circuit you are only powering two ICs and the logic voltage they use is only for signals. The other way to go about it is to use switching regulators but they are significantly costlier.

Using a voltage divider for power is pretty much a no-no. In order not to have significant current flowing through the divider when connected across a potential, you've got to use some pretty high resistances. When you go to power a device with the divider, one or the other of those resistances will be in series with that load. A good amount of the voltage you need for your device will be dropped across the resistor.

Keep in mind that the 78xx series of regulators are only good for about an amp. They both have big brothers available in a TO3 package good for about 3 amps.

- Scotty
186  Using Arduino / Project Guidance / Re: Solenoid & Stepper Motor power problem. PROTECT ME! on: November 29, 2012, 09:47:04 am
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Now if only someone could teach me how to power this contraption with only one power supply

Bit of a waste of power but:

19v-------7812 regulator
  |             |        |
  |             |        --------------------------7805 regulator
  |             |                                              |
  |             ---------- solenoid supply           ---------- logic supply
  |
  ----------- stepper motor supply

- Scotty
187  Using Arduino / Project Guidance / Re: Solenoid & Stepper Motor power problem. PROTECT ME! on: November 29, 2012, 08:01:07 am
Oops? Data sheet shows pin 9 of this device as Logic supply voltage and pin 4 as Supply voltage. It appears you have these swapped. - Scotty
188  Using Arduino / Programming Questions / Re: Help with RPM code on: November 28, 2012, 09:31:52 am
Found this:
Properties of Pins Configured as INPUT
Arduino (Atmega) pins default to inputs, so they don't need to be explicitly declared as inputs with pinMode(). Pins configured as inputs are said to be in a high-impedance state. One way of explaining this is that input pins make extremely small demands on the circuit that they are sampling, say equivalent to a series resistor of 100 megohm in front of the pin. This means that it takes very little current to move the input pin from one state to another, and can make the pins useful for such tasks as implementing a capacitive touch sensor, reading an LED as a photodiode, or reading an analog sensor with a scheme such as RCTime.

on the Arduino site under Learning/Foundations/Microcontrollers/Digital Pins.

- Scotty
189  Using Arduino / Programming Questions / Re: Help with RPM code on: November 28, 2012, 07:22:57 am
Why is a transistor needed? Couldn't the 10K resistor be in series with the photo-interrupter collector to 5V line and the emitter of the photo-interrupter tied to ground; the signal being read at the resistor-collector junction? - Scotty
190  Using Arduino / Project Guidance / Re: variable air solenoid control on: November 23, 2012, 05:09:44 pm
Recently had an opportunity to work on a vehicle (Infiniti) that had an Idle Air Control valve with a stepper motor control. Perhaps some automotive devices would work. Not all automotive valves are just open/closed.

- Scotty
191  Using Arduino / Project Guidance / Re: variable air solenoid control on: November 23, 2012, 08:33:05 am
I am confused. Are you trying to regulate air flow or air pressure? - Scotty
192  Using Arduino / Programming Questions / Re: need help to toggle between 2 pins and 2 leds on: November 18, 2012, 09:50:50 am
One way to program for that would be to use a variable to keep track of how many times the momentary switch was depressed and to use switch / case (http://arduino.cc/en/Reference/SwitchCase) to control (turn on/power up) your output pins. After the count of three and your outputs have been turned off, reset the variable to zero.

You will need to use debounce circuitry or code to eliminate any false counts due to contact bounce( ).

Only very small relays can be driven directly from an Arduino pin; otherwise you sill need circuitry to drive the relay. If the relay is small enough to be directly driven with an Arduino pin you will have to connect a diode across the relay coil to protect the Arduino.

- Scotty
193  Using Arduino / Programming Questions / Re: need help to toggle between 2 pins and 2 leds on: November 18, 2012, 07:17:52 am
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power up pin 12
What does 'power up' mean?

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LED attached from pin 13 to ground
Through a resistor, right?

Nothing in your code has anything to do with pins 10,11, or 12 so you can't expect anything to happen on those pins. Is that the part you are needing help with?
 
- Scotty
194  Using Arduino / Project Guidance / Re: measuring the length sum of multiple workpieces on: November 11, 2012, 10:37:15 am
I think that installing the photo sensor in a small length of tubing would eliminate any ill effects from ambient light. In the future a solution for that problem would be to use a modulated ir receiver and an ir led. A common use is a tv remote. Most use 38khz streams of ir light and the receiver is tuned to that frequeny and 'blind' to other light. There's a library available to generate the 38khz from the Arduino. - Scotty
195  Using Arduino / Project Guidance / Re: measuring the length sum of multiple workpieces on: November 10, 2012, 08:14:29 am
Debouncing suggests you are using a device with contacts, such as a switch. A photo sensor has no contacts so debouncing is not necessary. - Scotty
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