Here is a fun project you can do with your kids. It’s a project box with battery, switches, LEDs, vibrating motor, and whatever else you can come up with. it uses header pins and jumper wires to enable the user to connect circuits. Read More…
The useless machine is a simple box with a switch and motor, when you turn on the switch the lid opens and the arm swings out and turns off the machine and then retracts. It is so simple but brings a smile to the face of everyone that tries! The Useless Machine was not created by me, it can be found in Make Magazine and in numerous Instructables and DIY articles online. Read More…
A potentiometer is a variable resistor used to resist electrical current.
A diode is a semiconductor that only allows current to flow in one direction, it is a one way valve for electricity.
Diodes come in all shapes and sizes, the most important difference in them is the current rating, i.e. how much you can push through without overheating and burning the diode up. Here I demonstrate different diodes.
Here I show how to test a diode. Testing is done with a multimeter, an analog multimeter is preffered.
Here is some information on the numbers you may find on a diode.
Specifies semiconductor material
Specifies type of device
Diode – low power or signal
Diode – variable capacitance
Transistor – audio frequency, low power
Transistor – audio frequency, power
Transistor – high frequency, low power
Diode – sensitive to magnetism
Transistor – high frequency, power
Switching device, low power, e.g. thyristor, diac, unijunction
Transistor – switching low power
Switching device, low power, e.g. thyristor, triac
Transistor – switching, power
Surface acoustic wave device
Diode – voltage reference
The characters following the first two letters form the serial number of the device. Those intended for domestic use have three numbers, but those intended for commercial or industrial use have letter followed by two numbers, i.e. A10 – Z99.
I searched for days trying to find a commercial sound localization sensor or info on how to build one. Sound localization is what the human ear does when it determines that a sound is coming from the left or right. After talking to some gentlemen over at the Arduino forums I realized that it wasn’t going to be as simple as I thought.
I finally hacked together something that works great for my first try, there is a lot of work to be done though. The sensor works fairly well from a foot or so away, after that you really feel the limitations of my circuit and only doing a volume comparison from the microphones.
I am aware that the LM324N is not specifically a comparator but can work as one, it seems to do the job.
If you are interested there are some videos on YouTube regarding sound localization but they only demonstrate the sensors and give no helpful information on building one yourself.
I may in the future try to use an ARM Cortex M3 proto board I purchased from Texas Instruments (EKK-LM3S811 Evaluation Kit) to do phase shift comparison calculations for sound localization, the Arduino is nowhere near fast enough to do this. After reading some information I believe you need to be able to sample and do a calculation in 10-50 micro seconds in order to get usable data.