This tutorial was featured on the official Arduino blog on 3/9/2011
In this week’s arduino tutorial, we take a bit of a detour and focus on some key elements of electrical engineering design that we’ll be using in future episodes. Included amongst these topics is Ohm’s Law, current-limiting resistors, pull-down and pull-up resistors, voltage dividers, potentiometers, analog inputs, and voltage regulators.
If you’re yearning to learn more after watching this video, I’d suggest you check out Jeri Ellsworth and Dave Jones on youtube. They offer videos about everything from circuit design to pinball machines.
You can download the files associated with this episode here:
Distributed under the GNU General Public (Open-Source) License.
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March 9, 2011 at 12:52 pm
Hello, I’m a beginner and got lots of questions. Now i’m trying to do a WMR project. The concept is like the WMR will follow the fuzzy logic rules to avoid obstacle. The problem i got is, I have no idea how to make the motors, sensors and Arduino UNO work together. The 4 motors are 250W 24V DC Motors, and sensors are Maxbotics LV-EZ0 ultrasonic sensors. Would you like to teach and help me about this?
March 9, 2011 at 10:07 pm
You should control the motors using a mosfet, see this post: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1253402459
Take a look at the datasheet for the sensor: http://www.maxbotix.com/uploads/LV-MaxSonar-EZ0-Datasheet.pdf You can choose to grab the distance from the sensor via serial, or by querying it as an analog input.
March 14, 2011 at 5:39 am
Thanks so much for the tutorials. They are great and really well explained. I finally understood what a pulldown resistor is good for and how a voltage divider works. thx again.
July 6, 2011 at 11:13 pm
How can I open the .sch file for the schematics? Thanks for these excellent tutorials.
July 7, 2011 at 11:03 pm
That’s an eagle cad file. You can download eagle here: http://www.cadsoftusa.com/
August 14, 2011 at 7:40 am
Hi, thanks for ur tutorials. I just wanted to ask what was actually that java com 23 that u used in putting the signals of 1, 0 ,1 etc….
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November 5, 2011 at 5:06 pm
Hi I just watched this video and sorry but I don’t understand the pull down resistor bit. I was looking at the diagram at 7:05 and wondering shouldn’t the resistor be on the other side of the switch. But even before that how does current flow through when the switch isn’t even enabled?
December 31, 2011 at 6:46 pm
We are concerned with the voltage that the arduino pin sees. When the button is not enabled, and we use digitalRead() to see what the arduino is “seeing” on pin 8, the pulldown resistor ensures it sees a zero. When the button is pushed, it “sees” a 5V signal with no resistance, and a gnd signal with 10k resistance, so the 5V signal “wins”.
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December 2, 2011 at 11:32 pm
Jeremy,
Thanks so much for your tutorials. Being a noob, without your step by step teaching I would be lost!
I do have a question about this tutorial. You mention that the led will drop 2 volts automatically but you do not explain why.
Any further explanation would e greatly appreciated.
Thank you.
December 31, 2011 at 6:47 pm
The LED is using energy to generate light. That energy comes in the form of voltage. The voltage drops across an LED because the potential energy is being converted to light energy.
December 7, 2011 at 10:42 pm
Jeremy,
Thanks for the excellent explanation of voltage dividers and regulators. Such circuits had been a mystery to me until I discovered your blog.
Keep up the good work.
Michael
December 13, 2011 at 2:37 pm
Hi Jeremy – *love* your tutorial series. Your explanations seem to be much simpler than many of the books I’ve read. I have a question about tutorial 3 where you’re working out the resistance required to safely operate an LED. You say that the voltage will be 3V when working out Ohm’s Law for the required resistance. I was expecting 5V, as this is the voltage supplied by the battery. Where does the other 2 volts go?
Thanks very much – I’ve now subscribed to your Twitter feed and your YouTube channel. Keep up the amazing work!
December 13, 2011 at 2:40 pm
About 2V drops over the LED, so that leaves 3V to drop over the resistor.
December 19, 2011 at 5:41 pm
Hello Jeremy. Thank you for your tutorials. They are awesome!
I am really new in electronics, so also in Arduinos. But I took the challenge to make an EL-wire suit with 12 different wires. These I want to control with 6 buttons. Everything needs to be portable.
So… I want to buy 1 Arduino, a Protoshield and a mini breadboard.
On this mini breadboard I need to connect 6 buttons with the Arduino. Following the tutorials I made a scheme (a schematic picture of how the breadboard would actually look like). But I am completely unsure if it is correct/possible.
Before I am going to buy all the expensive stuff for my suit, I need to know if this is possible.
Can you please take a quick look at the image? I am sorry for the baby-like-image, but I am not familiar with electrical symbols…
Please find the picture here (I am Dutch, so it is a Dutch upload site)
http://www.uploadarchief.net/files/download/arduino5pushbuttons.png
Thank you very very much!
December 31, 2011 at 6:51 pm
Your schematic looks reasonable to me.
January 16, 2012 at 6:44 pm
Jeremy,
in the voltage regulator, as I am understood, already has its own capacitor build inside. my question is, what is the need of another capacitor outside the voltage regulator? how that contribute to the function of voltage regulator itself?tq
January 18, 2012 at 9:01 pm
Voltage regulators do not have a capacitor built in – the caps that you need for decoupling power lines are generally pretty big, and would be impractical to construct using layered silicon.