Cable Length

Hello guys. i am using one Arduino Uno along with 2 nos. DS18B20 liquid temperature sensors. I want to keep 10-12m distance between each sensor and the arduino itself. i am worried about the voltage drop in the way. Please help.

While your waiting for a reply, try a Google search on;

‘ds18b20 long cable’

Might be some useful info to be found.

Try it and see if it works. Part of the fun of this hobby is trying things out to find out of they will do what you want them to do. Here's just 2 of many examples of things I tried that might or might not have worked:

  • I have I2C running over about 30m of cable. Many will tell you it won't work. It does.
  • I needed a 50VDC to 12VDC power supply, I could not find one. I tried using a mains to 12V PSU with 50VDC as the input. It might not have worked, but it works just fine.

No harm done by trying stuff and don't let anyone tell you it won't work.

vibhor23:
Hello guys. i am using one Arduino Uno along with 2 nos. DS18B20 liquid temperature sensors. I want to keep 10-12m distance between each sensor and the Arduino itself. i am worried about the voltage drop in the way. Please help.

Your concern is not voltage drop, it is the capacitance of the wiring that limits the speed of data transitions.

PerryBebbington:
I needed a 50VDC to 12VDC power supply, I could not find one. I tried using a mains to 12V PSU with 50VDC as the input. It might not have worked, but it works just fine.

If it is rated for operation at 110 V, then operating at a third of its rated voltage is not surprising. I would not expect it to deliver its full rated output current however.

If it is rated for operation at 110 V, then operating at a third of its rated voltage is not surprising. I would not expect it to deliver its full rated output current however.

It was rated for 230V. It delivers enough output for my purposes, which is all I am bothered about.

PerryBebbington:

  • I needed a 50VDC to 12VDC power supply, I could not find one. I tried using a mains to 12V PSU with 50VDC as the input. It might not have worked, but it works just fine.

OK, going totally off topic, but this one really surprises me. Such power supplies are normally built out of a transformer (to bring down the voltage and offer electric isolation - not that this seems to work well as I've measured 230V AC on a +12V output, after I got buzzed by it a few times and wondered why - I have seen schematics where there are capacitors in parallel with the transformer, dunno what they do other than passing the high voltage AC to where it doesn't belong), followed by a switching supply to produce the regulated nominal voltage.

DC simply won't work if there's a transformer in the way. So your PSU has NO isolation between input and output whatsoever.

wvmarle:
OK, going totally off topic, but this one really surprises me. Such power supplies are normally built out of a transformer (to bring down the voltage and offer electric isolation - not that this seems to work well as I’ve measured 230V AC on a +12V output, after I got buzzed by it a few times and wondered why - I have seen schematics where there are capacitors in parallel with the transformer, dunno what they do other than passing the high voltage AC to where it doesn’t belong), followed by a switching supply to produce the regulated nominal voltage.

DC simply won’t work if there’s a transformer in the way. So your PSU has NO isolation between input and output whatsoever.

Noting your posting count, some of your recent posts have puzzled me, and this is a case in point. I really have no idea what you are trying to add to the discussion. :cold_sweat:

Where Perry referred to a power supply he used a 230 V mains to 12 V supply. In times past, these might have used a transformer operating at the mains frequency - 50 or 60 Hz - but no longer. :astonished:

It is nowadays a switchmode supply, rectifies the mains to DC with a bridge rectifier (so it can be supplied equally well with DC or AC), buffers it with a large capacitor, chops it to a supersonic frequency AC to feed a quite small transformer, the output of which is rectified and smoothed with relatively small capacitors and chokes, with feedback to the mains-side choppers to regulate the output voltage.

Essentially all such supplies inherently provide isolation from the mains input. Of course, it is considerably simpler for a specified-purpose 50 V DC to 12 V DC “buck converter” to have a common negative between input and output as it uses only a single-winding inductor but that is a quite different case.

Paul__B,
Yes, exactly.
And my overall point in making the comment in the first place was to encourage Vibhor23 (and anyone else) not to be afraid to try stuff, even if others have said "that won't work". Maybe it won't, but trying is both fun and educational.

"...trying is both fun and educational."
Nice! It could be the forum's motto.

I'm using DS18B20 in on cca 30m STP cable with few connectors in path, 5V is in - without any bigger problem.
Important thing for reliability is to follow the rules for 1-wire bus, see the Maxim's web for a guide.

Did miss something? This is what I read:

Hello guys. i am using one Arduino Uno along with 2 nos. DS18B20 liquid temperature sensors. I want to keep 10-12m distance between each sensor and the arduino itself. i am worried about the voltage drop in the way. Please help.

This is my answer:
Voltage drop will not be a problem. Do use the 3 wire connection, the parasitic will give you noise problems. I have used them to about 25 meters from the arduino without any problems.
Good Luck & Have Fun!
Gil

Thank u Kind Sirs - PerryBebbington, Paul__B, Budvar10, gilshultz -for your guidance. I did some experiments with some wires.
With 10m 32 SWG wire - i got 1.4V voltage drop
With 15m 25 SWG wire - i got 0.3V Voltage drop.

Theoretically, when i calculated, it was showing that i will get 40% voltage drop.
Also, Can CAT5 Ethernet cable be used here???
Just a thought - kindly correct me if i am wrong -
What if i connect 3 Arduino NANOs with all three sensors and keep them 15-20m apart and let them transmit the data(digital Signals) to fourth MAIN arduino. Will this be more accurate than the first idea...kindly consider this scenario.for me, accuracy is everything.