Pictured below is a device we made recently to control window blinds so that they automatically close in the evening and open in the morning to give the impression that someone is at home when they are away on holiday.The motor set up with these particular blinds is a small 3 Volt DC unit, but the controller is powered by 12 Volt DC. The motor needs to be turned forwards to open the blinds and turn in reverse to close the blinds. Therefore a pair of relays are used (as explained here: Reversing the Polarity of a Motor with Two Relays) to give the reversing polarity output for the motor.

A programming button is fitted to the device which is used to set the number of seconds that the motor is to run to fully open or fully close the blinds. In addition, there are a pair of microswitches which act as limit switches ensuring that if blinds reach the end of their motion before the expected time, the motor will be turned off so that it does not burn out under the heavy load of fighting resistance. Therefore, the motor runs until either the user programmed run time has elapsed or the limit switch is hit. If there was not a time limit, then if the blinds became jammed, the limit switch would never be reached, and again there would be the risk of the motor burning out.

If you need any type of motor controller or timer, please email neil@reuk.co.uk with details of your exact requirements.