Posted by Justin on December 26, 2009 – 5:03 am
I was thinking about my turntables that I have and about spinning trance and thought to myself that I don’t have any way to tell what the BPM is of the song, there are mixers that have this built in and I have seen rack mount stand alone units but nothing small and portable. My device would be handheld with stereo jack and rca jacks for input. Knowing that all analog music is just a wave form, why not measure the wave of a specific frequency (e.g. bass) using a band pass, then calculate when the peaks hit and get the BPM.
This seems like a very simple thing to do but wont know till I start putting something together.
parts that I will need:
- Arduino or other ATmega chip
- RCA connections
- Darlington transistor pair (chip or separate transistors)
- a few LEDs
- Resistors asst
- 2x 7 or 8 segment display or serial LCD module
- maybe more parts, odds and ends
This could be made into a kit or a sellable project. Hopefull in Jan I will be able to start putting this together for my proof of concept and show it off….
Update:12/26/09
Just thinking on how would i calculate BPM, so I started with Google….didnt get very many specific code, alot of applications that do it for you but no real source code to extract the equation from so i kept looking, and found this http://www.conradaskland.com/blog/2008/02/how-to-calculate-delay-time-to-tempo-beat/
He explains on how to calculate the delay time between beats
* Delay time for crotchet in ms = 60000/BPM (Beat Per Minute)
* Delay time for Quaver in ms = 60000/BPM/2 (Beat Per Minute)
* Delay time for Semi-Quaver in ms = 60000/BPM/4 (Beat Per Minute)
so I used my Horrible math skills and came up with
BPM= 60K/Delay , then so on and so fourth.
so now the hard part pattern recognition, The tactile Metronome project seems to be the closest on what I want to create there project is here http://wayneandlayne.com/metronome/ , This should give me a good start on my project/
Posted by Justin on December 21, 2009 – 6:30 am
I needed a very simple tilt switch for a project my friend is working on, and i decided to go cheap. all that’s need for this hack, is a straw with wrapper, a BB, 2 wires and a little bit of electrical tape.
Start by opening up the straw and keep the wrapper, tear the wrapper in half, one is used as part of the plug for the top the other is for the bottom plug. Now roll the half the wrapper, after its rolled tight wrap a little bit of electical tape and insert it into the straw, make sure its tight. you can use a lighter to melt it a little butnot too much or it may start on fire. For the other plug, this time wrap the wrapper around one of the wires, make sure you have stripped at least 1/4″ of insulation. roll it a few times, the add the other wire to the roll after a few wrapps of the other one. now roll them both together and in the end you should have 2 leads sticking out of the plug and there not touching. Check for shorts first in the plug. Now add a BB to the straw and insert the other plug. Now you have finished the super quick and dirty Tilt switch. My design can be improved on but for now it will work for right now. you may substitute other cylinders/tubes for the switch housing(e.g. pens, paper rolled around a pencil, pvc tubing).
Posted by Justin on December 20, 2009 – 10:50 pm
When I was thinking of how to run more than a few servos from my arduino, I was contemplating, the best approach to regulating the voltage for the servos. Currently I am testing my setup with 4 HS-311 Hitec servos, and a 7.2v 1.5A LiPo battery. This is a simple and easy setup, its not the most energy efficient but it works for this purpose. Currently i am not going to improve this simplistic design till i need more power or efficiency. Parts used – LM317 TO220, DC power with center pin Positive, 22o Ohm + 680 Ohm carbon film resistors, .003 micro farads Cap, .001 micro farad electrolytic Cap, Header pins and wire. The schematic i used was the first one out of the data sheet nearly on the front page. At first it was tough for me to figure out how to get the resistor values, i looked and looked and stumbled upon this site that automatically calculates the correct values for resistors per your needed voltage.
Site needed here
after calculating the needed voltage and finding the needed resistors, for my 5V, I used 220 on R1 and 680 on R2, I might change them out to get the 6.5Volts I would like to have, since my servos are rated up to 6V. This extra voltage will speed up the turn speed by micro seconds and add a few more grams of torque. But that’s for a later project.
After soldering all the connections
I put 12V wall wort and tested the voltage, Perfect reads about 5.18 volts, so i left it hooked up for a min to see fi any smoke fires or excesive heat build up with no load,(i thought i had accidentally bridged a connection) No sparks no fire, time for a load test. I start hooking up the Servos to the headers, 6 pairs of 3 pins, only 4 used. Then loaded up my arduino with a simple servo.write to 90 degrees and then sweep. All servos work, now to actually put a load on the servos to see if the power source can handle the load, since I don’t know what the amperage rating on these servos, nothing was stated on the box or any other info I could find.
Video and load test still to come!
Posted by Justin on December 7, 2009 – 9:19 am
I recently found this site selling this weird putty that reminded me of Mighty Putty, But this stuff is so much better than that.
It dries flexible and stays flexible at all temperatures. So i decided to buy some here http://sugru.com/ . So i bought 2 of there multi colored multi hack pack. I just hope it ships before February 2010. Next i will have to find a place that sells polymorph.
