I have built this kit to control our bathroom fan. I would like it to turn on only the fan, with one short press of a push button switch, and then stay on for about 5 mins. I have wired up the timer but it only stays on for about 2 mins. (This is with the ‘trim pot’ turned to max time) Is this a fault or the norm when it is wired up without switching on the room light at the same time? Can the ‘time on’ be increased by changing a component eg. resistor R5 which is in series with the trim pot ? In these times of talk of climate change it seems a wast of energy to have to turn on a light just to get the fan going, and to have the fan running every time you put the light on when you do not need the fan as well.
This is not possible.
If you increase the time the kit will be unstable.