Need Help To Design A Circuit

[Dagwood]

I need some help to design an automotive type circuit. It will consist of two 12 volt inputs, and one 12 volt output. The first input will always be on. The output should also always be on unless the second 12 volt input comes on. When that happens I want the output to drop to zero for until approximately one second after the the second input turns off and remains off. When the second input does come on, it will turn on and off in about one half second intervals until it shuts off completely. Thanks for your ideas.

 

[Hero999]

I'm not meaning to be rude but what is the point of this?

What exactly are you trying to do?

This isn't one of the things that you would normally do in isolation; it is typically part of a larger project. It is easier for us to provide help if we can see the bigger picture.

 

[Dagwood]

I'm trying to control some extra lighting on my motorcycle. Right now I have extra LED lighting that functions as running lights and turn signals, both with their own separate 12V input. To make the turn signal more pronounced, I want the running light to turn off when the turn signal for that side is flashing.

 

[TheVictim]

A relay would probably be the most efficient way. On older bikes you might even be able to use the N.C. and N.O. contacts on the existing turn signal relay, but more modern signals would use solid state switching.

You could connect your running lights to the N.C. contacts on the relay and your turn signal to the N.O. contacts, then have the turn signal current control the relay coil. You might need to use a driver to do this.

 

[Dagwood]

I don't think the NC/NO relay would be any different than what I have now. In between flashes the running light would still be on. I want total darkness in between flashes.

 

[TheVictim]

If you put the running light on the normally closed contact, it will be OFF when the relay is energized, and your turn signal connected to the normally open contact will be ON. Is this what you want to happen? From your description that is what is sounds like.

 

[MrDEB]

2 DPDT relays, each one controlling running lights/turn signal lights for corresponding side.
using Eclipse circuit (see url) for corrning/turn signal lights (delay circuit so coil stays activated while signal is flashing)
have a sch I drew but will post tomorrow if need be - its getting late

https://www.electro-tech-online.com/attachments/turninglights-gif.2685/

 

[Dagwood]

TheVictim - regarding your idea, I envision that working only if I can tap into the turn signal circuit before the flasher to get a constant power source to drive the relay while the signal is flashing. I'm unable to do that because the turn signal is controlled be a module which starts it sequence by a single 12V pulse from the turn signal switch which is a momentarily on switch. The signal controller then runs for a preset duration depending on the speed of my bike.

MrDEB - I actually came across that idea before you posted after searching previous posts last night. Thanks for pointing it out to me. All I need to do know is to determine what cap and resistor values to use for the 1 second delay off.