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Device to maintain current flow for a number of seconds.

Hi, I am trying to set up a system for my daughter to protect her driveway. I have installed a couple of sensors that, when the beam between them is broken, switch on some floodlights. I need these lights to stay on for a number of seconds and don't know how to acheive this. I bought a timer delay relay, but this wasn't the right thing because as soon as the current to it is removed (when the relay in the sensor opens), is dissables the timer rely. 

Can anyone recommend something that would keep the lights on for a limited period of time.

Thanks

Peter

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Comments

January 6, 2020 08:25

Thank you very much for your helpful response. I think the item you have recommended would fulfill the function that I am looking for perfectly. If the device that I have ordered doesn't do what I want, I will certainly purchase what you have recommended. The one I have on order only cost a fifth of your recommended one, but I am sure that there would be a significant difference in quality between the two. Thank you again for you time and wish you a very happy 2020.
Regards
Peter

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January 6, 2020 13:44

@PeterWright your module should work. The L and N to the board must be connected all the time to the module. The fan is replaced by your light (check the power rating of the board for the light) and switch K is your relay contact. If it doesn't work, post back here to discuss before buying anything else.

January 6, 2020 08:26

Hi Peter, further to other reply this I believe is an industrial example that would work.
https://uk.rs-online.com/web/p/timer-relays/8285161/ and the data sheet
https://docs.rs-online.com/6eb8/0900766b8168f0e3.pdf
I have also attached a timing and connection diagram that identifies the connections.
How does that compare with the part you have?

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January 6, 2020 08:26

Hi, I have ordered a circuit that is used to maintain power to a bathroom fan for a period of time after the light has been switched off. Hopefully this will do the trick.
Regards
Peter

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January 3, 2020 08:51

Hi, thank you for your reply. I have done my best to produce a simple wiring diagram (probably not very professional). Currently I have everything on that diagram installed except for the timer delay relay. So the lights do flash on, due to the relay in the sensors, but don't stay on for any length of time. It seems to me that as soon as I take the power away from the timer delay relay coil, the relay will stop functioning altogether and default to open circuit.
Regards
Peter

0 Votes

January 6, 2020 08:26

Hi Peter, what is the part number of your off delay relay/timer? Usually (though there are many varieties) these have elecronic circuits built in that require permenent energisation. They can also be quite complicated to work out how to configure as they are 'universal' with many options such as delay on, delay off, one shot etc., I'm not even sure if this is a suitable part as I couldn't work out the wiring circuit required at a quick glance but they typically look like this. https://uk.rs-online.com/web/p/timer-relays/8966822/ I would be interested to see what part you have.

January 3, 2020 08:51

Hello Peter, I think you may have the right solution but perhaps wiring the delay relay in wrongly from the switched power instead of the actual power. Can you attach a simple wiring diagram.

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