Tuesday, February 23, 2010

How to make PCBs using toner transfer method

First design the schematic and convert it into board layout, in Eagle layout. Making schematic first helps because Eagle will show you clearly if you make any mistakes with the PCB.
Print the pcb traces out onto semi glossy photo paper. 

Then quickly take this paper, cut out your design and place it face down onto some blank PCB board. Then use an iron and press the design on to the board. Use a lot of pressure and ensure all traces of the design make good contact with the blank PCB. Keep it pressed for at least three minutes. After removing the paper you get something like this:
 
sorry about the flash on image 

There are many alternatives for etching liquids, and you can use the one that suits your taste. I use ferric chloride: it’s cheap, can be reused many times, and doesn’t require heating. Actually, moderate heating can speed up etching.
 

Do not directly heat it, use hot water and put the ferric chloride container in it to speed up the process.
After etching the pcb looks like:

A few drops of thinner (nail polish remover works well) on a pinch of cotton wool will remove completely the toner, bringing back the copper surface. Rinse carefully and dry with a clean cloth or kitchen paper. After drilling your home made pcb is ready to use.


Wednesday, February 17, 2010

JDM Programmer

A very simple programmer for PIC16F628/28A and PIC16F84/84A.

Schematic:

Components:
D1,   5.1v zener diode
D2,   8.2v zener diode
D3-D6,  1N4148
Q1-Q2,  BC550c
L1, red LED
L2, yellow LED
L3, green LED
R1, 4.7k ohm
R2-R3, 470 ohm
R4, 2,2k ohm
R5, 10k ohm
IC1, 18 pin socket
X1, DB9 female
C1, 22uF/16v
C2, 100uF/16v