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136  Using Arduino / General Electronics / Re: Flyback Diode Selection and PWM on: July 23, 2012, 08:53:04 pm
Thanks Runaway Pancake,
Do I understand correctly that while the motor is in operation that there will be no voltage drop on the diode that is in parallel then?
137  Using Arduino / General Electronics / Flyback Diode Selection and PWM on: July 23, 2012, 07:59:41 pm
Can anybody point me in the right direction on how to select the correct flyback diode for a small dc motor <1A (or any DC motor for that matter)? I've been searching and searching on several forums and am getting conflicting answers. Some say that the 1N4xxx type are fine as long as the voltage rating is at least 10x the motor voltage and at least the same current rating as the motor. Some say that a Schottky Diode must be used because of the fast recovery times needed with PWM like this one:
 http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Components/General/1N5819.pdf

Also, how will a diode in parallel, like a counter emf diode, affect the voltage going to the motor? Does it reduce the voltage by ~.7V?
138  Using Arduino / General Electronics / Counter EMF Protection on: July 22, 2012, 08:50:57 pm
I'm interested in improving my small robot to drive two motors with this motor driver. It looks simple enough to wire, program, and use.


My questions:

1. Do I need counter emf diodes in my circuit in addition to my motor driver board?

2. If so, what do you suggest?

3. Towards the bottom of the page on the Polulu link it says that temperature can be lowered and current improved by adding a heat sink. How do I do that? Is it as simple as using thermal tape with a small heat sink such as this?
http://www.sparkfun.com/products/10746

Polulu TB6612FNG Dual Motor Driver:
http://www.pololu.com/catalog/product/713

It's also the same as Sparkfun's:
http://www.sparkfun.com/products/9457

For my motors:
http://www.pololu.com/catalog/product/1117

For my Gearbox:
http://www.pololu.com/catalog/product/114

Motor Supply Battery:
9v rechargeable Ni-MH battery

Arduino Supply Battery:
9v alkaline or possibly another rechargeable 9v Ni-MH battery


Thanks in advance
139  Using Arduino / Sensors / Re: PIR Sensor Not working with 9-volt power supply on: July 22, 2012, 12:19:57 pm
Could you include a link to the specific PIR that you are using? I would like to see what kind of voltage/current the PIR requires. If you can include a sketch or schematic of your curcuit (or describe it the best you can. Also post your code.
140  Using Arduino / General Electronics / Re: Any Good General electronics books for Beginners? on: July 22, 2012, 12:05:01 pm
http://www.overstock.com/Books-Movies-Music-Games/Electronics-For-Dummies-Paperback/3200441/product.html?cid=202290&kid=9553000357392&track=pspla&adtype=pla&kw={keyword}

and I like the site: http://www.allaboutcircuits.com/
141  Using Arduino / Sensors / Re: PIR Sensor Not working with 9-volt power supply on: July 20, 2012, 10:24:28 pm
Stick the negative probe of your meter down the center of the barrel jack, and touch the outside of the barrel jack with the positive lead. You should get about nine volts before you plug it into the arduino. If that is satisfactory, plug the barrel jack into the arduino then double check your power by measuring the voltage on the power rails of your bread board. Just use a couple small wires and measure with your meter. Maybe you could post a good picture of your whole set up and we could help more.
142  Using Arduino / Sensors / Re: newbie needing help with buttons and loops on: July 16, 2012, 03:40:21 pm
http://www.ladyada.net/learn/arduino/lesson2.html

http://hacking.majenko.co.uk/the-while-loop
143  Using Arduino / General Electronics / Re: Convert 6v to 5v to power stand alone Atmega328 on: July 12, 2012, 10:45:21 pm
Quote
What happens if I use less than 5v and something like this http://www.sparkfun.com/products/341 ?

Bro, It's only 3.7v. But you have the right idea. Do some battery research. Didn't you say that you needed more than 250mA? Just ger a 9v NiMh  rechargeable battery from Radio Shack or Office Depot along with an LM 7805 and be done with it. Do that, and I'm sure anybody will be happy to help you wire it. And there are already tons of tutorials about it anyway.
144  Using Arduino / General Electronics / Re: Convert 6v to 5v to power stand alone Atmega328 on: July 11, 2012, 09:13:25 pm
Quote
A zener diode seems like the cheapest and easiest solution, but is it reliable? Is there a benefit to using something like this http://www.sparkfun.com/products/107 ?
If you scroll down to page 3 of the data sheet it says that it needs 7v minimum for input. I mentioned that earlier.

A 5v zener diode should be fine. Just check the data sheet.
145  Using Arduino / General Electronics / Re: Convert 6v to 5v to power stand alone Atmega328 on: July 11, 2012, 08:40:01 pm
An easy and cheap way would be to use a zener diode rated at 5v. The problem with using resistors in a voltage divider circuit is that as the battery drains, your 5v becomes much less. It all depends on how much current you need or that may not be a problem. You only need 3.3v minimum right? The low drop out regulators are expensive (~$7). You may want to consider getting something like a rechargeable 9v NiMH battery. They're cheap, available at office supply and electronics stores, and throw away alkaline batteries are crap. Then you would be able to use a LM7805 voltage regulator. The LM7805 is cheap, but you need to input at least 7v.
146  Using Arduino / Motors, Mechanics, and Power / Re: HELP 4 motors 1 arduino on: July 11, 2012, 07:58:52 pm
A TIP120 is much less likely to burn up than your PN2222.
147  Using Arduino / Sensors / Re: multiple maxbotix LVEZ on one UNO? on: July 11, 2012, 07:44:44 pm
You need to divide Val_1 and Val_2 by 2 in order to get inches. If you want centimeters, you have to then multiply that result by 2.54.
http://www.arduino.cc/playground/Main/MaxSonar

Also your sensors are almost certainly interfering with each other. Can't you just use one sensor? If not you need to daisy chain them or learn how to trigger them. There are instructions on how to trigger them earlier in this thread.
148  Using Arduino / Sensors / Re: multiple maxbotix LVEZ on one UNO? on: July 05, 2012, 07:17:18 pm
http://www.instructables.com/id/Getting-started-with-the-Maxbotix-sonar-sensor-q/
149  Using Arduino / Sensors / Re: multiple maxbotix LVEZ on one UNO? on: July 01, 2012, 12:41:10 am
very good sketch! I think you should try to use the pwm mode of the maxbotix sensor. It's not much different from what you are doing now. You don't have to daisy chain it either. They won't interfere. They are on different sides If the door right? I'll walk you through it. Just post some code using the links I gave you. If you don't understand I'll help you. I know it's frustrating, but I'm here to help. We'll make it happen.  
150  Using Arduino / Sensors / Re: multiple maxbotix LVEZ on one UNO? on: June 30, 2012, 05:42:17 am
the maxbotix sensors will work, and if they are on opposite sides of the doorway they won't interfere with each each other. check the links from my last post. Get them wired up and write some code. Post a schematic and your code here, and I'll check back to help you.
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