$100 4-20 mA simulator?

[TwoBlocked]

Just picked up a cheap 4-20mA simulator (also does +/- 10V). Problem is the display shows what the mA output is trying to be, but not what it really is. For example, if set to 12 mA, and the loop is open, it reads 12 mA! Great, so then I need to put my DMM in the circuit also? What I need is not for calibrating, just troubleshooting. Any suggestions for something around $100?

 

[Mr. Serious]

I don't know if anybody builds it the way you want it. You probably will have to build something yourself.

I did some calculations and looked up some parts, and this is the simplest way, but the current adjustment will be able to go below 4mA and above 20 unless you put in additional trimmer resistors and tweak it quite a bit.

Put the following in series:
A 12V DC battery or power supply.
A 330 Ohm resistor rated at least 1/10 watt.
A 3k potentiometer or rheostat rated at least 1/10 watt. This is your current adjustment knob. Maybe you can get one with an actual knob.
The current loop inputs of the Murata DMS01-CL 4-20mA power meter. This is your $100 component, the rest is cheap. They've decided to stop making it, so build your thing soon if you're going to use this meter.
The rest of your current loop, device under test, etc.

Also connect the 12V source up to the power inputs of the Murata meter.

If you want to build the whole thing a lot cheaper, use a different digital panel meter, but you'll have to put another trimmer resistor/potentiometer in parallel with it to scale the reading correctly, and you can do the calculations for that part.

If you want to build the thing highly accurate, there will be much more design work involved and you would use an actual 4-20mA driver chip available from various manufacturers, or an op-amp based circuit.

 

[don_resqcapt19]

There is a lot of commercial equipment that will do what you want, but not in the $100 range.

 

[TwoBlocked]

Last century, I would tape four 6 volt batteries together and wire in a rheostat and multi-meter.

 

[ptonsparky]

I would think you would always require a load, be it a meter or resistor of some sort. Dialing in 12 ma won’t do much good until has a load to push it through.

 

[drcampbell]

This ought to do what you want, and you can put it together for under $100.
(unless you opt for a fancy-schmancy ten-turn precision potentiometer & ten-turn knob)

 

[tank728]

There is a lot of commercial equipment that will do what you want, but not in the $100 range.

Can you provide a make and model

 

[zbang]

Google is your friend - search for "4-20ma signal generator" and you'll see a bunch.

 

[4-20mA]

https://www.amazon.com/Seesii-Adjustable-Historical-Resistance-Calibrator/dp/B0BHSHV2X5/ref=asc_df_B0B965GNGS&mcid=1276ca4a88e8334ea5c049938dc65651?tag=bingshoppinga-20&linkCode=df0&hvadid=80676855879503&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4584276319718666&msclkid=6c4b4c3a3f3316dcc6c429f1a53ef144&th=1

Reads like it should do what you want. For less than 100$, might be worth a try.

 

[Eddie702]

I think Kele Assoc. in TN sells a "signal generator" if that is what your looking for.

 

[milmat1]

Can you just add a cheap ammeter to your existing tool ?

 

[Electromatic]

I have looked and not found a cheap milliamp clamp meter. I don't see why manufacturers can't put a third jack on a clamp meter nor slap a clamp on a DMM!
However, the $23 0-10v/4-20ma signal generator I bought seems to operate accurately. ?

 

[kwired]

Just picked up a cheap 4-20mA simulator (also does +/- 10V). Problem is the display shows what the mA output is trying to be, but not what it really is. For example, if set to 12 mA, and the loop is open, it reads 12 mA! Great, so then I need to put my DMM in the circuit also? What I need is not for calibrating, just troubleshooting. Any suggestions for something around $100?

I got something similar for pretty cheap. don't use a lot but does come in handy at times. Mine does 4-20, 0-10V, RTD, maybe more can't recall. Can be a source or receiver of most the signals it can work with. Haven't used it for anything in a while.

I mostly got it for RTD functions. Simulators I've used before I made myself out of potentiometers. Always seems to be extra resistance throwing things off with those setups, plus you need to check resistance with your meter then switch it over to the device that is to read the signal and is more time consuming and less accuracy than this cheap simulator is. Most what I have needed to use it on needs reasonable accuracy but not necessarily high precision accuracy.

 

[Birken Vogt]

I have looked and not found a cheap milliamp clamp meter.

Not recommending this site particularly but I have one of these and have been using several for decades now.

https://www.tequipment.net/BK/316/Clamp-Meters/

Response is very slow to changes in current but I think that is unavoidable in a clamp meter measuring tiny DC.