Hi guys
I've got a circuit that works to a degree but I needed to make a modification. Below are links to the 2 circuits.
The first works in as much as it has an instant on-off action when current is sensed across the bridge (8a-8b). The circuit, given a stable connection, will switch transistor T7 and switch the red LED on, and green off. This is instant (milli-seconds) and would, in ideal circumstances be fine. Unfortunately the source of the current across 8a-8b is not as continuos as I would like and cannot be made firmer, so the intermittent switching oscillates the red and green LED's.
Circuit 1
**broken link removed**
So with that in mind I hunted for a time delay circuit and found the 'timer' circuit as shown in Circuit 2 below. I had hoped that putting it between the 'detector' and the 'signal control' circuits would work straight away as now, when current flows through 8a-8b it would trigger the 5 second timer which would, in turn, activate the red signal. Then any short breaks in the current across 8a-8b would be covered by the 5 second delay, and the 5 seconds would be restarted.
Circuit 2
**broken link removed**
Unfortunately with the 'Timer' circuit added, the timer is triggered immediately the 'Detector' circuit is connected, even without a current across 8a-8b. This switches the signal to red. Once the time delay is up, the signal switches to green for less than a second and then the timer is activated again.
I have no idea what is triggering the timer as nothing should be switching transistor T10, and even if it was, why then would the timer expire and restart when this circuit should reset while the timer is active if triggered again, so should never run out.
The switch SW1 is a bypass and when the detector is not connected it activates the timer as it should so I know the 'Timer' circuit with 'Signal Control' works.
Anyone any ideas what may be/is triggering the timer in 'Circuit 2' or maybe another way to add a release delay to 'Circuit 1' without using the timer circuit in 'Circuit 2'?
Hope this makes sense and sorry for the large images but couldn't read the labels when I down-sized.
Angie
I've got a circuit that works to a degree but I needed to make a modification. Below are links to the 2 circuits.
The first works in as much as it has an instant on-off action when current is sensed across the bridge (8a-8b). The circuit, given a stable connection, will switch transistor T7 and switch the red LED on, and green off. This is instant (milli-seconds) and would, in ideal circumstances be fine. Unfortunately the source of the current across 8a-8b is not as continuos as I would like and cannot be made firmer, so the intermittent switching oscillates the red and green LED's.
Circuit 1
**broken link removed**
So with that in mind I hunted for a time delay circuit and found the 'timer' circuit as shown in Circuit 2 below. I had hoped that putting it between the 'detector' and the 'signal control' circuits would work straight away as now, when current flows through 8a-8b it would trigger the 5 second timer which would, in turn, activate the red signal. Then any short breaks in the current across 8a-8b would be covered by the 5 second delay, and the 5 seconds would be restarted.
Circuit 2
**broken link removed**
Unfortunately with the 'Timer' circuit added, the timer is triggered immediately the 'Detector' circuit is connected, even without a current across 8a-8b. This switches the signal to red. Once the time delay is up, the signal switches to green for less than a second and then the timer is activated again.
I have no idea what is triggering the timer as nothing should be switching transistor T10, and even if it was, why then would the timer expire and restart when this circuit should reset while the timer is active if triggered again, so should never run out.
The switch SW1 is a bypass and when the detector is not connected it activates the timer as it should so I know the 'Timer' circuit with 'Signal Control' works.
Anyone any ideas what may be/is triggering the timer in 'Circuit 2' or maybe another way to add a release delay to 'Circuit 1' without using the timer circuit in 'Circuit 2'?
Hope this makes sense and sorry for the large images but couldn't read the labels when I down-sized.
Angie