humidity sensor HIH-4000 4-20mA current output

[stuplja]

Hi,

A little help how to convert HIH-4000 voltage output to current output 4-20mA, maybe with LM317 (something like you can find about temperature sensor LM35 and LM317 in LM35 datasheet) or you have better suggestion, I'm stuck

http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/DS005516.PDF
page 6

Thanks in advance ...
Stuplja

 

[aljamri]

What is your sensor output range ?

 

[atferrari]

You have an humidity sensor. You also mention temperature sensors and one well known voltage regulator. Can you clarify your own ideas first and them come back with a more clear question?

 

[stuplja]

OK, here's what I need:
humidity sensor with HIH-4000 with current output 4-20mA

I mentioned temp sensor LM35 with current output 4-20mA and it's done with LM317 and it works well, so I mean somebody made something similar for humidity sensor HIH-4000, that's the reason for mentioning LM317...

thanks again ...

 

[stuplja]

forgot, here's datasheet for HIH-4000-001...

**broken link removed**

 

[stuplja]

also forgot , HIH-4000 have linear voltage output 0.958V - 4.026V for 0-100% RH humidity

 

[ericgibbs]

also forgot , HIH-4000 have linear voltage output 0.958V - 4.026V for 0-100% RH humidity

hi,
Do you mean this LM35/LM317 App.??

Does the 4mA to 20mA for the HIH, have to be referenced to 0V.?

 

[stuplja]

Exactly that application for LM35/LM317!

HIH-4000 have linear voltage output from 0.958V for 0%RH and 4.026V for 100%RH.

 

[ericgibbs]

Exactly that application for LM35/LM317!

HIH-4000 have linear voltage output from 0.958V for 0%RH and 4.026V for 100%RH.

hi,
Does the 4mA to 20mA for the HIH, have to be referenced to 0V.?

ie: is the remote sensor resistor connected to ground.?

 

[stuplja]

Hi,

No, zero offset for HIH-4000 is 0.958V and the slope is 30.680mV/%RH.

 

[ericgibbs]

Hi,

No, zero offset for HIH-4000 is 0.958V and the slope is 30.680mV/%RH.

hi,
I dont mean the HIH, I mean the remote equipment that 'reads' the 4mA to 20mA loop current.

ie: what is the application that the 4 to 20mA is driving into.?

 

[stuplja]

Hi,
PLC Unitronics Jazz, 4-20mA current input, 154ohm input imedance.

 

[ericgibbs]

Hi,
PLC Unitronics Jazz, 4-20mA current input, 154ohm input imedance.

hi,
This would work , providing the guitar and V2I converter dont share the same power supply lines/common.

 

[stuplja]

Hi,

Thanks a lot, I'll try it immediately and let you know...

Also, maybe you have solution with LM317, like in PDF for LM35 and here's schematic:
HIH-4000 instead LM35?, but I couldn't find more details about this schematic and I made it and it works well for temperature.

 

[stuplja]

Hi,

It works great!!! , thank you very very much.

I didn't have CA3240 (instead 2xCA3140) and I used TL072 for test and it works well!

Just one more question about calibration, I mean, how to set output current exactly from 4-20mA, can I replace 250ohm on emitter with trimmer to adjust output current?

Again thanks

 

[ericgibbs]

Hi,

It works great!!! , thank you very very much.

I didn't have CA3240 (instead 2xCA3140) and I used TL072 for test and it works well!

Just one more question about calibration, I mean, how to set output current exactly from 4-20mA, can I replace 250ohm on emitter with trimmer to adjust output current?

Again thanks

hi,
Thats good news,
I would split the fixed 225R into say a 200R fixed and a 100R variable, in that way you will get a finer control of the current.

NOTE: its the 225R which sets the current, the 250R to the emitter is the 'loop resistance'

 

[stuplja]

Sorry, mistake about trimmer ...

 

[stuplja]

hi,
Thats good news,
I would split the fixed 225R into say a 200R fixed and a 100R variable, in that way you will get a finer control of the current.

NOTE: its the 225R which sets the current, the 250R to the emitter is the 'loop resistance'

I've done that, but, at the end, I used 56ohm and 50ohm multiturn trimmer to get "real" value and also, I'm planning to go to meteo station to compare results with their RH sensors

One more thing, can you, please, tell me in which software you done simulation and can you send me file to try myself? I suppose it will help me to better understand whole circuit.

Again thanks very much

 

[ericgibbs]

I've done that, but, at the end, I used 56ohm and 50ohm multiturn trimmer to get "real" value and also, I'm planning to go to meteo station to compare results with their RH sensors

One more thing, can you, please, tell me in which software you done simulation and can you send me file to try myself? I suppose it will help me to better understand whole circuit.

Again thanks very much

hi,
Download LTspice, free, from Linear Technology also join the Yahoo LTspice users group.