Critical resistance situation

I'm in a situation where my resistance changes between two states (infinity and 500 Mega ohm ).I want to be able to notice a change when it switches from one state to the other state.

Unfortunately I can't change the value of both states.

My question is , Is there a bridge or a certain circuit whose total resistance depends on the existence of a specific resistance.

In other words, I want the bridge or circuit to give a normal total resistance (10k or 100k or whatever) when my resistance is injected into the circuit and open circuit when my resistance is removed.

Can I do that ? Can I do with passive elements ?

If this is not possible with passive elements , what circuit should I use ?

by ahmadsayed
October 14, 2018

Yes, that is possible, but very challenging.

First you must realise a very high standard of cleanliness and keep everything very dry.

Then I need to know more about your sensor, the 500M/infinity resistor.

  1. Is one end grounded?

  2. What is the highest voltage that can be applied across your resistor without causing sparking or inaccuracy?

Thanks. mike

by mikerogerswsm
October 15, 2018

The sensor is a MEMS sensor which has two terminals .. one for actuation from a dc supply and one connected to the ground of the supply..

highest applied voltage is 8 volts

by ahmadsayed
October 15, 2018

I would suggest detaching the MEMS from ground and putting in a 1M resistor. Make this one side of a bridge, and add resistors to make up the other side of the bridge. Then use a comparator to compare the bridge voltages. Will post circuit anon.

by mikerogerswsm
October 15, 2018

by mikerogerswsm
October 15, 2018

The LF111 is obsolete, use LF356 instead.

by mikerogerswsm
October 16, 2018

No Answers

No answers yet. Contribute your answer below!

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.