October 28th, 2008

MOSFET Headphone Amplifier

MOSFET Headphone Amplifier

As we all know headphone amps are not cheap to buy. I think this is the main reason that drives the hobbyist to make their own amps. Most people are familiar with the popular C’Moy headphone amp which is cheap to make and it sounds nice.

But there also other designs available, for example this class A MOSFET headphone amp. The author designed and build it because he’s 32 ohm Grado SR80 headphones didnt’t sound good on it’s computer soundcard.

An IRF610 MOSFET was used by the author but there is a wide variety of FET devices that can be used instead. Unlike the C’moy amp this amp was primarily designed to sit on a desk, it’s bigger the MOSFET needs heatsink cooling so this wouldn’t fit the portable category of amps.

A LM317 regulator is used for the constant current source, and the current is limited to about 250mA. In the end the sound is better than on the sound card and it was a small investment as most parts were salvaged.

It’s not too difficult to build something similar but it will sure help to have some experience with similar circuits.

MOSFET Headphone Amplifier: [Link]

October 28th, 2008

DIY Game Boy

diy-game-boy

DIY game console ? there are not many projects out there on this subject, mainly because of the ammount of work and time you have to put into something like this.

Matt, the author of the DIY Game Boy, got over this issues and manged to get it done. The core of the project is an Arduino that controls all the other modules.

There is very little soldering requiered on this project as it’s mainly constructed using modules and shields. The source code is posted on the project page so you should have no problem on making something similar.

DIY Game Boy: [Link][via]

October 24th, 2008

Synth Blog

Aris dropped me an email to let me know he launched an electronics blog, more exactly a DIY synt blog. Check it out, you might like it.

October 11th, 2008

Soldering Hint

There are lots of ways you can clean your soldering iron tip, but i never saw one that cleans so well. Have you ever tried cleaning it with one of these ?
soldering hintsoldering-hint-3

I think it’s main use is somewhere in the kitchen, but it works great for cleaning the soldering iron tip. Or if you like the pro version of this cleaning sponge you can take a look at Curious Inventor, I have to admit i first saw the idea there.

and the results…

before cleaning

before cleaning

after cleaning

after cleaning

These things cost about $0.5 from where i got it so it’s cheap investment for a clean tip 🙂

October 10th, 2008

Super TV-B-Gone

I liked the tvbgone kit from Ladyada the first time i saw it but i never had the time to build it, until a week ago. But than i decided to build a more powerful one that could turn off TV’s from even greater distance. I came up with a design that consists of 48 IR LED’s and a ATmega8 that will send the signals to the LED’s.

the led board
Unfortunately i wasn’t paying attention on a small paragraph from Ladyada that was saying “Use 940nm IR LEDs.” so without knowing i bought 860nm IR LED’s (L53SF6C from Kingbright). I did not knew at that time that this is going to affect the distance at which the device works. Why L53SF6C ? they seemed nice because at 50 mA they have typical 100 mW/sr so allot more power than the F3(940 nm) series which had 30 mW/sr at 50 mA.

I arranged the LED’s in 4 rows of 12 pieces and the resistors fit quite nicely between the LED’s. I used four BD139 NPN transistors to drive the rows. It took me hours to drill and then solder this board(48 LED’s and 48 resistors mean 192 holes plus the other parts)

super tvbgonesuper tvbgone

the controller board
The controller board contains an ATmega8 chosen because of it’s 8k memory needed to store all the codes, an 8 MHz crystal, an LED, a tact switch and some resistors and capacitors. I designed the board so that it can also be used for other projects.

super tvbgonesuper tvbgone

the code
It took me some time to adjust the code from tiny85 to ATmega8, getting the timers right was tricky but i managed to get it done. Also i had to delete a couple of codes to fit it in the 8k’s of the ATmega8.

the power
The whole project is powered from a Nokia BL-5B battery which was ugly fitted onto a peace of PCB 🙂 . I can’t seem to find a decent socket to hold such a battery. I’ve run the circuit for over a week every day and the battery is keeping up, and when it gets discharged I’ll simply charge it inside of an old nokia phone.

super tvbgone

Testing it
Well as you can imagine the first thing i did was to test it on the TV’s in my place, it worked perfectly. Next i wanted to test it on a larger scale so i took the device onto a nearby supermarket were they have a bunch of Tv’s onto a wall. I had to conceal the device somehow so they don’t kick me out of the store 🙂 so i placed the device inside a CD case. I don’t know how much the case is obstructing the signal, but it was turning off TV’s from a distance of 20 meters.

super tvbgone

Probably choosing the right wavelength LED’s would double the distance, and by using a clear case the distance would double again, but that’s just a guess.

The boards were designed in Eagle and fabricated by me using the photo etching technique.

I’m planing to build a newer version, in fact i already sent the files for PCB fabricating. This new version will use only 4 LED’s just like the original design, and will be smaller thus easier to conceal and it will also use ATmega8 for the controller. I’ll post pictures as soon as i get it done.

some more pictures..

super tvbgonesuper tvbgonesuper tvbgonesuper tvbgone

downloads



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