Komputer tips

This is a 10 LED chaser using NE555 timer and 4017 decade counter.You can use upto 15vin this circuit.If you want to use filament lamps or high power LEDs use transistors at the outputs to amplify the current.The output of the circuit as below. The speed of the LEDs can be changed by using the potentiometer.And it depends on the value of C1 ,R2 and R1 too.Change values to get your desired speed.Higher the value of C1 slower the LED chasing speed.You can reduce the number of outputs by connecting the pin 15 reset of 4017 to a output pin of 4017.For an example let's say you just want 5 outputs then connect the pin 15 to the pin 1. PCB solder side and Component Side.Print at 300 DPI using a laser printer on a photo paper.Do not change any other settings. For assistance in making PCBs please visit my article on  How To Make PCBs at Home

The circuit above can control speed of your DC motors or Computer Fans.If you use this to control speed of DC motors please use a diode to protect the Transistor,brush-less fans -OK.You can change the variable speed range by changing the value of R1 potentiometer.But don't use very high values,its pointless. The transistor used here is a NPN 2n3055,it can handle up to 15A and 115W of power.And this transistor can handle up to 60V.So if you're using this for PC fans you can add more in parallel.Normally a computer fan uses about 0.4W of power.Some powerful ones may use about 7W of power.If you don't use so much power then you can use a low power transistor like C1061,D313 etc. If you don't want to change the speed too often or hard to find a potentiometer or just willing to make this out of scrap you can use a Trim resistor for R1. The transistor may heat up very much and its essential to use a Heat sink.If you can,do not solder the transistor to the PCB s...

When you work with electronics PCBs are very important.They are essential for circuits.PCBs have so many benefits than strip boards and dot boards and they last longer.Before going any further if you need to design your PCB from circuit schematic read our article on PCB Designing With Eagle CAD to design your PCB like a pro. In this article I'm going to teach you how to make PCBs using toner transfer method.This is very easy if you have all the materials at home.If you have a laser printer at home its going to be more easier.But before printing the PCB you need to edit the .ps file you printed using EAGLE CAD CAM processor to make more copies and get the most from your papers.To do so you need a photo editing software like Photoshop and GIMP.Let's get to work. Editing .PDF files for toner transfer print out ps2pdf.com and convert your files to .pdf first.You can also use any other online or offline converter.But DO NOT change any DPI values or page sizes. #2.Open Ado...