Help Needed with Simple Relay Circuit

Situation: My septic tank currently has one red warning light that turns on when the tank is full. When the waste water level is high enough it triggers a float switch. The red lights tells me it's time to empty the tank.

As things stand now, what happens if the bulb goes bad or I've lost electricity to the warning light circuit? The situation is ripe for an unexpected overflow.

Plan: I'd like to build a better warning indicator. I recently purchased two LED lights, one red and one green. Both lights will be mounted in a weatherproof outdoor electrical box. I'll drill two holes in the box cover plate, one for each light. Here is my light bulb logic. A lit green LED light indicates there is power to the circuit. When the float switch is triggered, the green light turns off and the red light turns on and it's time to have the tank emptied. Should I ever find both lights off, I'll know the situation needs to be looked at.

I've attached a crude drawing of what I think the circuit might look like. I know I need a relay in this application but I'm not sure what kind to get. Both LED lights operate on 120v. So I'm guessing I'll need a 120v relay.

Questions: Is my circuit accurate? And what type of relay do I need and can you point me to where I can purchase it. OK, that's three questions.

Keep in mind I'm not an electrical engineer. But as a homeowner of 25 years I've done plenty of basic to intermediate electrical work on my home. Last year I trenched and ran power to my detached garage and installed a new 60 AMP lug. All this was needed to power a new 240v table saw.

Thank you,

John

by JohnH76
July 10, 2017
Add comment...

Please sign in or create an account to comment.


1 Answer

Answer by jzdeath

The relay setup is incorrect but is not needed anyway. I would suggest removing the relay. Just connect the greed LED to the power side of the switch. Then the green LED will always be on. If the green LED is off you know power is off.

+1 vote
by jzdeath
5 days, 14 hours ago
Add comment...

Please sign in or create an account to comment.


Your Answer

You must log in or create an account (free!) to answer a question.

Log in Create an account


Go Ad-Free. Activate your CircuitLab membership. No more ads. Save unlimited circuits. Run unlimited simulations.

Search Questions & Answers


Ask a Question

Anyone can ask a question.

Did you already search (see above) to see if a similar question has already been answered? If you can't find the answer, you may ask a question.


About This Site

CircuitLab's Q&A site is a FREE questions and answers forum for electronics and electrical engineering students, hobbyists, and professionals.

We encourage you to use our built-in schematic & simulation software to add more detail to your questions and answers.

Acceptable Questions:

  • Concept or theory questions
  • Practical engineering questions
  • “Homework” questions
  • Software/hardware intersection
  • Best practices
  • Design choices & component selection
  • Troubleshooting

Unacceptable Questions:

  • Non-English language content
  • Non-question discussion
  • Non-electronics questions
  • Vendor-specific topics
  • Pure software questions
  • CircuitLab software support

Please respect that there are both seasoned experts and total newbies here: please be nice, be constructive, and be specific!

About CircuitLab

CircuitLab is an in-browser schematic capture and circuit simulation software tool to help you rapidly design and analyze analog and digital electronics systems.