I am having problems which seem to be attributable to oversensitivity of the ‘start/stop’ part of the circuits. 1. Upon switching on the mains supply the relay o/p closes by itself (unacceptable in this application). 2. The operation of the load (a 12V solenoid) directly from the o/p relay by activating the ‘start’ button (wired remotely) causes the ‘stop’ to work. 3. Feeding the o/p relay into a second, high current, relay (even with no load on that one) thus causes a rapid alternation between ‘stop’ and ‘start’, so that this relay ‘chatters’. 4. Operation of a completely separate circuit (also a 12V solenoid), starts the timer o/p as well; the only link seems to be that the wires of the two circuits are near one another in places.
I have tried using a separate power supply (a Velleman K1823) and transformer for the timer; also a completely separate supply from a battery charger, all without success.
A separate issue is how to get the time adjustment sensitive enough to time accurately within the range 5-20 seconds? I have tried lowering the capacitor C2 to no avail.
So…I would be most grateful for any suggestions to enable me to solve this problem, which I realise is not new to the forum, either by changing the values of components, adding new ones, or failing all else, use of a different circuit altogether.
Many thanks in anticipation of your assistance.