I need a circuit to hold the last 4-20 ma dc signal until it receives a new signal.

This is for a pressure tester.

The pressure is increased untill the test subject ruptures, and the
pressure transducer signal signal drops to 4 ma, I want to hold the
signal value at the point of rupture until it is manualy reset or receives a new signal.

Any help would be greatly appreciated.

Thank you in advance.

bobmcm

 

What you probably need is a peak detector instead of just a S&H. Usual implementation is a precision rectifier followed by an opamp. You could also go with an IC that does all these, like PKD01 from Analog Device.

You have to convert the 4-20mA signal to voltage first.

 

Hi Bob,

If you want to send me an e-mail address I will send you a circuit. I'm guessing you can measure the result with a voltmeter and that the build up of pressure happens fairly slowly.
Is powerpoint okay?

Ronv@wbhsi.net

 

Hi Bob,
If you want to send me an e-mail address I can send you a circuit. I assume you can measure the output with a voltmeter and that the pressure builds up fairly slowly.
I'd paste it here but I don't know how.
Is Powerpoint okay?

Ronv@wbhsi.net