If you make a lot of prototyping, especially with SMD components like myself you need to make for each design its own pcb. With SMD’s the one layer design usually isn’t feasible and since the component pins doesn’t run trough the board  the double layer approach results in many vias, even for a simple schematic you can have 50 of them.

Off course everybody can order from the factory trough hole plated pcb and they are off the hook, that is the professional solution and for the end product I do the same. But that costs more, there is a lead time and if there is some error on the board or on the schematic, you need redesign and order another one.

I personally use home-made double layer pcb’s for my prototypes, with photo method and some design constraints like track width, spacing,  clearance, the results are quite good.

Double layer pcb home made vias

Yes, that’s nice but it has a lot of vias, and can be painstaking  to make the connections for each via by running  through a thin wire, soldering one end then soldering the other end, cutting down the excess, because for each via you have to handle the wire, the soldering iron, the cutter resulting a great “overhead”. I admit this was my solution and took hours to make each via separately, until somebody showed be a clever trick, but that’s enough talking, here are the pictures:

You need some thin copper wire:

You need some thin copper wire:

First anchor one end of the wire by soldering to one side:

First anchor one end of the wire by soldering to one side:

Run through the vias(like sewing) the wire:

Run through the vias(like sewing) the wire: Run through the vias(like sewing) the wire:

Solder each end:

Solder each end: Solder each end:

Start cutting as close as possible(on each side):

Start cutting as close as possible(on each side):

The result:

The result

Nice, round bumps :)

Nice, round bumps :)

And after soldering the TQFP package:

And after soldering the TQFP package:

As you can see, the vias underneath the TQFP doesn’t cause any problem, although more attentions is needed when soldering. Fast and simple, hope you get the spirit and start tinkering.

This is just a board I made to work with at school because normally I would not build anything on pic. I just wanted to show once again, that using the photo etching technique and some effective component placing you can obtain really nice results wether your building trough hole or SMT. The board has a quad op-amp for inputing and outputing analog signals and a max232 to provide a serial interface. It will be mainly used to gather data from sensors and send it on the serial interface to a computer.

PIC16F876 development board

March 22nd, 2009

Asus Eee PC car charger

Since I often find myself on the road with my battery drained out and because I intend to use my Eee Pc together with a GPS module as a navigation system I thought it would be a good idea to make myself a car charger. The charger would have to output 9,5 V 2.5A, and it would have to be able to maintain the output voltage constant over variations of the input voltage. Of-course there are lots of voltage regulators these days that would fit my circuit, but I chose to use the LM2576 because such a charger has already been build and tested here (also featured on Youritronics here).

Here is the schematic of the charger:

Eee Pc charger schematic

After ordering the needed parts I noticed that the  inductor is slightly bigger than I expected it to be, so fitting the board into a small box became a bit of a problem. But I managed to designed the board so that it fits into the chosen box. I also fitted a medium sized TO-220 radiator so the circuit would dissipate the heat even in continuous use of the charger. The pcb was made using the photo etching technique and I tried spraying it with a mix of colophonium and alcohol that would act as a soldermask. The result is not pretty but I hope it will protect my board from corrosion.

EeePc charger pcb

After the soldermask dried it was only a matter of minutes until I assembled and tested it. The charger works great, the output voltage remains constant over continuous variations of the input voltage. Now all I have to do is close the box, solder a cigar lighter connector and pack it into my arm rest compartment.

Asus eee pc car charger

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In response to the high interest shown by the readers on a spectrum analyzer posted here I decided to make a new design, that will be available in shop as a kit. The movie shows just a stage in the developing process, where the filters were being tuned. The final design will be powered by an atmega64 and will have 20 bands with 20 LED’s on each band.

I am now searching for a pcb manufacturer to get a good price on manufacturing the boards, then it will all be ready.. stay tuned.

September 16th, 2008

New PCB’s from BKRtech

As you can see from the picrures they are great, and the projects they’ll server are great also.

new pcb from bkrtech that is gonna be used for AVR DOPER programmer

new pcb from bkrtech that is gonna be used for AVR DOPER programmer

new pcb from bkrtech that is gonna be used for AVR ATmega640 dev board

new pcb from bkrtech that is gonna be used for AVR ATmega640 dev board

new pcb from bkrtech that is gonna be used for AVR ATmega64 dev board

new pcb from bkrtech that is gonna be used for AVR ATmega64 dev board

Some of these projects will be submited here on Youritronics for more free PCB’s , i only hope more of you join the program because, there are more free pcb’s to be given.



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