Hi & Low input to high output circuit help

Very simple.

Connect a resistance of 1k ohms from 24V and connect it to your signal input. The current through resistance will be 12mA to 24mA, enough to drive the opto-coupler LED. When input control is floating, no current through optocoupler LED will flow. Use the optocoupler output to control the power supply.

You can also connect a 6V relay to the input. One end of the coil to input and other end of the coil to 6V DC. Relay will be ON for zero volt and 12V but will be OFF for floating input. Select the relay coil resistance that can be directly driven by the control input. Use Coto-relay low power type 5V operated. Go to www.cotorelay.com/ for more information. They make very high reliability relays in small package.

If you have any further question then write to me again. I think this should solve your problem easily.

Two six volt globes in series connected to your 12v supply. If you designate where they join as 0v you then have your high signal being + 6v and your low signal being -6v. Floating will be zero. A 5 or 6v relay can be used to switch your 12v on or off. If polarity is an issue add a bridge rectifier.

This is very crude but effective. A more elegant design could be developed using the same principle but with electronic components. Depends on the application.

Its very simple to take a low output whenever your input circuit is going in foating state. U can drive a relay from your 12volt 200 mA supply and use its contact with desired voltage lable to take status as low or high,for further help on this topic U may contact me at i.sanjai@gmail.com . I hope that U will got the solution regarding your problem related to Automation.

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