The following circuit shows a CD4060 in a timer circuit, intended to hold a relay (with a transistor driver) on for about an hour, then turn it off. I want to have a reset switch so that at any time, I can push it to start the timing from an hour again.
orm. It shows mostly the power and inputs. For testing, the outputs are connected to a bank of LEDs with current-limiting resistors, showing every available state (Q4-Q10, Q12-14), but I did not show that in the diagram, for simplicity. It counts correctly. The relay is not in the circuit yet.
ONE output is shown, Q14 at pin 3, with a diode whose purpose is to latch the timer, to stop counting when it reaches Q14, or about one hour. The latching effect works correctly. Q14 is also connected to an LED as described above.
The 120K resistor and the 100nF capacitor are a power-on reset circuit, and that has been working every time I tried. "Trying" means turning of the master power switch (before the power transformer in the power supply) and then turning it on again.
PROBLEM: the only thing that does not work correctly is the manual reset pushbutton across the 100nF capacitor. As I understand it, the 4060 RESET (pin 12) can be connected HI to achieve a reset. However, pushing the button, whether quickly or for a second or two, usually results in a non-zero state for the 4060 registers, typically with Q5-Q9 HI.
Why does the manual reset not clear all registers to zero, and how do I fix it?
UPDATE: in the original post, the resistor from pins 12 to 8 was said to be 1M, but it was 120K. Per suggestions in comments and answer, I changed it to 10K. Reset button works as long as I don't hold it down longer than say 1/2 second. When holding it down, releasing it leaves the registers in a non-zero state.