Help with 4060 delay off circuit

Hello everyone I am just getting started with electronics and I am finding it very fun so far, but I have hit a roadblock in a project I am trying to accomplish.

The project involves a PIR sensor which will turn relay on and off. When the sensor is unoccupied I want a timer to keep the relay on for a certain period of time (1 minute to 30 minutes adjustable) before shutting off. The timer should reset every time a new detection is made.

I have the output from the sensor (it goes to 5.5 V when detects a person and 0 when unoccupied) going to the reset of my 4060 timer which should hopefully restart the timer every time there is a new detection.

I also have another branch from the output of the sensor going to a schmitt trigger to smooth it out.

One problem I am having is the 4060 puts out a very long pulse (it is a 50% duty cycle) when the timer hits the designated time. I need to make this pulse shorter.

The last thing I need help with is trying to get some sort of bistable circuit so that when the output of the schmitt trigger is high it should toggle to a high state and keep it there. Then when the output of the timer (which should be a short pulse) goes high it should toggle low. When both are toggled high at the same time, the state should be high (set should take priority over reset).

If there is a better way to create an adjustable delay off circuit to accomplish what I want using the 4060 please let me know. I tried to put as much information as possible, but if there is any other information you need please let me know. Thanks.

You could use a simple resistor-capacitor differentiator to give a short pulse when the 4060 period ends, and a CD4013 as a set/reset latch.

I actually just thought of the same thing today in fact. The 4013 looks like just what I was looking for, thanks. Could you explain what you mean by a resistor capacitor differentiator? Also I'm having some trouble with the pulses from the 4060. Using the 2^13 output and a clock set by an 11k resistor and a 330nF cap I should get a pulse every 68 seconds from what I calculate. However the first pulse goes high very close to this and the pulses after that take much longer. I have my clock set up just as the attached image shows. Then my output is coming from pin 3. I am just wondering why I am not getting a consistent pulse time.

A simple differentiator. The example RC values will probably do for your purpose and aren't critical. View attachment 65199
By 'first pulse' do you mean the rising edge of Q13 output? That will occur half-way through the repetition cycle of the 4060. The next Q13 rising edge will be a whole cycle later.

Forget the 4060. There are much simpler solutions. You need a retriggerable monostable. CD4538. The datasheets shows you exactly of how to do what you want.

https://www.electro-tech-online.com/custompdfs/2012/06/CD4538BC.pdf

Page 3 for the explanation and page 4 for the circuit.

Being CMOS it can handle a wide range of supply voltages.

Plus there are two identical monostables totally independant of each other in one chip. They cost pence too.

I actually got it working with the 4060 and the 4013. Thanks for all your help. I will try the 4538 possibly in the future.

WTP Pepper said:

Forget the 4060. There are much simpler solutions. You need a retriggerable monostable. CD4538. The datasheets shows you exactly of how to do what you want.

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You are not going to get 30 minutes from the 4538 with reasonable sized components. He should stay with the 4060.