Single 12V power source for particle and 4-20ma loop receiver

I have another question for using the current loop receiver.  The previous post I submitted https://www.controleverything.com/content/4-20ma-Receiver-Help, was a huge help and got me reading accurate measurements with 4-20ma receiver.  I am now trying to package the entire device up to place into the field and am running into some issues.  I have a 12v battery, solar panel and a charge controller that we use in our field gauges.  The charge controller has 1 12v output for a device which I am hooking up to our pressure transducer sensor, and a 5v usb output which I hook up to the particle with the 4-20ma receiver attached.  Under this setup the shunt resistor on the 4-20ma reciever tries to burn up (lucky I bought those extra boards).  I believe this is because of a shared ground between the sensor and the board.  I've heard that is a no-no.  Any ideas on how to separate the 12v circuit for the sensor and the 5v needed for the particle while only having one battery would be greatly appreciated.

 

 

J

Just a reminder, this setup was working when the 12 v battery was connected only to the sensor by itself.  Also the shunt resistor only gets hot when the usb power is attached to the particle (and thus the reciever is powered up).

 

Thanks again

B

you can put a power isolator between the charger and the particle photon.

something like this.

http://www.digikey.com/product-detail/en/cui-inc/PDM2-S5-S5-S/102-2736-ND/4009660

 

J

Thanks for the info.  We'll give it a try...

 

Jim

J

So, I bought a usb isolator with a similar power isolator, but the issue that I am running into is that those isolators seem to be 400ma or less at 5v.  I was really hoping to feed more current to the electron to keep the 3.7 battery charged.  Would it be possible to add the isolator directly to the 4-20ma current receiver board, or to add that as an alternative configuration?

 

Thanks

Jim

B

most of the isolator comes with very low current, rather than using this isolator between electron the battery use it between electron and 4-20mA receiver board.

the ideal solution will be like this, a board with 4-20mA receive and on board power isolator as well as an I2C bus isolator. we do have a custom board service which you can use if you need a lot of these boards.

 

 

 

J

I agree that would be ideal, but it could also be an inline board between the electron and the current loop receiver (or any of your I2c sensors for that matter).  I would think that many users of the 4-20ma receiver boards who are using these devices remotely in the field (on a 12v solar setup) would want such a configuration as an option.  I'd need more details on the price and quantity necessary to justify a custom printing of these boards.  We are looking to deploy up to 50 of these devices in the field over the next 2 years.  I don't know if that is a lot in your mind or not, but as I said...I have to think that other remote field users would desire a similar setup.    

 

Feel free to email me if you want to take this offline from the community discussion.  

Jim