4 Channel Relay Module

this is a little PCB i made yesterday, it is a simple relay control module for micro-controllers, in this PCB i put together 4 channels, but the design accepts much more.

Here is the schematic:

Click to enlarge!

Here is the copper side printable image. (300dpi)

Click to Enlarge!

• Technical Explanation:

1. This board was initially designed for 4x 5v Relays but it is pretty flexible, its blocks are well defined(Resistor, Led, Transistor, Diode, Relay), so you can add or remove how much relay blocks you want.
2. You may replace the leds for a jumper if you do not need them.
3. If you want to use relays with any other pull-up voltage, all you have to do is change the supply. Make sure you have connected the controller's GND as well.
4. The resistors values are not critical, for my prototype i used 470R but can be high as 2K2.
5. The transistors can be any smal signal npn like 2n2222, bc548, 2n3904 etc.

Click to download Eagle Files.