Also
Check the threshold voltage the inverter needs for a 0 and a 1.
You mention 10 volts , that's a fair skew rate needed , wonder how long the 555 takes to get to a 1 level on it's output ..
Also check when those output fets turn on , depending what's on the output connectors , there is likely to be a big dip in the power rail to the 555 and the inverters , which could cause spurious logic.
E.g. A long wire or inductive load on those fets could be a problem .
The led resistor also looks a bit high .
And check the on / off voltage of the fets with the resistance in their legs.

 

Hi - I understand re pins 9, 11 and 13.
But can you explain further using pull down resistors and also if possible, a circuit showing their use or a link to a typical diagram

This is how the circuit should be configured:
Instead of using pulldown resistors on pins 3 and 5 suggest using jumpers to tie those pins to ground until needed.
From the CD4069 Data Sheet:
Implications of Slow or Floating CMOS Inputs

 

Done most of what has been suggested. But still no further forward. All LED resistors lifted, CD4069 removed. All GNDs and Vcc buzzed out OK,

What seems to be occurring is that the gate of Q2 is not turning off.

Q1 is working fine, being driven by the 555 timer.

Gate - logic level 0 (0 volts) = Q1 is ON, and thus load is ON
Gate - logic level 1 (9 volts) = Q1 is OFF, and thus load is OFF

However Q2 is permanetly on.

Gate - logic level 0 (0 volts) = Q2 is ON, and thus load is ON
Gate - logic level 1 (9 volts) = Q2 is ON, and thus load is ON



There is nothing connected to Q2 except the 10k resistor. But why does Q1 work and not Q2

Maybe faulty Q2, is it normal though. Not sure if I have another mosfet, but maybe tomorrows job to swap Q2.

 

What are the loads on the MOSFETs?

 

Out with scope
What voltage are the gates getting down to , compared to other pins ?

 

What is the supply voltage?

What seems to be occurring is that the gate of Q2 is not turning off.

However Q2 is permanetly
Gate - logic level 1 (9 volts) = Q2 is ON, and thus

What is the supply voltage?

 

What is the supply voltage?

What is the supply voltage?

Battery 12v, but going down to 10v at end of day.

 

What are the loads on the MOSFETs?

Loads at present are only mA, but will go higher into the amps when I get things worked out

 

Battery 12v, but going down to 10v at end of day.

If the supply is 12V and the gate of Q2 is 9V that might be enough the keep the mosfet ON.
Or the mosfet is shorted.
Gate should be at 12V with a 10K resistor between gate and source and nothing else connected.
Is Q2 installed correctly?

 

It was doing my head in this morning; the readings did not seem consistent from last night.

One voltage reading on a drain was constantly dropping over 15 seconds. This seemed to be a capacitance problem.

I managed to narrow it down to the CD4069 chip holder. Pin1 in the holder was not making contact fully with the chip. Also found a track that ran nearby seemed to close to Pin1. So I replaced the holder and reran the close track.

Hey presto, all was working fine.

Soldered all the LED resistors back in. Still everything was working fine, and LED's flashing correctly.

So many thanks for all the help and assistance over the last few days. Thankyou.

 

It was doing my head in this morning; the readings did not seem consistent from last night

We’ve all been there. An incorrect reading, we try changes to fix it, nothing makes sense. Then we put it all back the way it was… and presto! It works fine.

 

When trying to trouble-shoot ICs and board problems, remember that you can have a different reading between the board connection and the IC pin.

Never assume that a proper connection is made between the two, whether it is IC socket, protoboard, or PCB.

 

One thing only briefly mentioned is that if the IC happens to lose it's common "ground" connection then the output will be high no matter what. And a poor ground connection on a proto board is a classic problem.