RO Water Controller - Drain Timer Board <<< Previous Next >>>

This board is fairly simple, it is basically just a series of resistors. There are a couple of connectors either side. Dependent on the position of the rotary switch dictates how many of the resistors are in the series. The more resistance the longer the time interval. The length of time is also dependent on the capacitor on the main board. Since capacitors vary in manufacturer you will need to experiment with different values of resistors to gain a precise time. Although the values I have listed here should give approximately the time specified. Since the project doesn't need precise timing they should be sufficient. The timer chip is located on the main board.

X1-1 through to X1-12 are connected to the poles on the 12 way rotary switch. The common pole of the rotary switch is connected to X2-2. X2-1 and X2-2 is then connected to X6-1 and X6-2 on the main board.

Time Interval:

Values of resistors:-

The Eagle board schematic can be download by clicking here and the PCB board can be downloaded by clicking here. (Please note that you will need the Eagle software to read these files)