I watch lots of Arduino videos. I am a High School Math and Science teacher. This was the best video I have seen in a long time. Short but loaded with details. Very well explained. Precise and to the point. Well done.
Very useful video and I have no NEST to compare. I too got both DHT11 and DHT22 sensors and found massive difference in the humidity. DHT11 sensed 51 while DHT22 sensed 77.
Exactly the information I need. I'm building a multi-roll filament dryer. It will have two fans inside and sense temperature and humidity at two locations inside, plus the outside air temperature and humidity.
The issue with wire length and the pullup resistor is not wire resistance. You'd have to use a LOT of wire just to get one ohm. not enough to affect the reading. Especially since the output is digital. The issue is noise. With a very high pullup resistor, like the internal pullup, it isn't very resistant to noise when compared to using a much lower resistance. In any case, for that you should use twisted pair to reduce noise pickup.
Hi. Are you not making more Arduino tutorial videos? Newest video is 4 years old. I hope you come back to make more because I really like your videos and the info you put in them. In this case you show how to read a DHT and print to OLED but you also mention the DHT humidity is no good. I have not seen this in any other tutorial. Others only show how to read sensors but lack deeper knowledge that you seem to have. So I appreciate your videos very very much! Thanks for sharing this and I hope you will be back to teach us even more!
Thank you for the comment, of course there's no way of knowing which sensor is correct, but since the Nest and the DHT22 are showing very similar humidity readings compared to the DHT11... Thanks for watching!
@@BrainybitsCanada That is still no indication that the nest is accurate just because one of the two sensors was closer than the other. Best to have a calibrated sensor of some sort as well as taking multiple readings over multiple temperatures and humidity. Some sensors wander more over a certain range. An example could be an analogue speed dial display in a car. It might be very accurate at 20 miles per hour. But get to 85mph and your actual speed is only 72mph.
When I piggyback a DHT22 sensor on the bottom of a 8266 D1 mini board to make it compact. The temperature displays 3-5°C higher immediately. Even with isolation foam between and the D1 mini not being warm at all, this stays the same. Once the sensor is 5cm away, all works fine. I’m wondering if this is some kind of interference. Now testing with the BME280 that seems a lot better and also has atmospheric pressure sensor. Thank you for making these videos.
Thank you for sharing your experience with the DHT22 sensor. I will be looking at the BME280 and another one in the next tutorial video. Thanks for watching!
I should have to calibrate every unique dht11 or dht22 I use. Wouldnt a simple offset in your code at your average target temp make it much more accurate?
Simply - you bought DHT11 with faulty humidity sensor. I have a few DHT11 and DHT22 (also DHT21) and all of them give similar results. New DHT11 return temperature in with decimal digit. You are using old libraries which don't support DHT11 well.
Thank you for your comment. I've got quite a few DHT11 and they all give me off readings on the humidity. Maybe I got a bad batch? As for the decimal readings on a DHT11, it would not be very useful since the specs of a DHT11 indicates it's only precise to + or - 2 full degrees. Unlinke the DHT22 which is accurate to + or - 0.5 degrees. Thanks for watching!
I think in new DHT11 Chinese used different components. Because I still have 4y DHT11 which has broken humidity sensor and temperature is much less accurate. Regarding temperature - it is measured using thermistor inside as far as I remember. I will have to disassemble both old and new one and compare them.
Very good vídeo, thanks. I just beginning on Arduino. I ask you, if I need to save the data, not using a display but just save the Data to Open on a excell. Can you made a video about that. Thanks
Nice and simple :) gj. Can you check new ones from Bosch BME280 and BME680? I got some fun readings from those 2 especialy if i use them with esp wi-fi boards. Tnx
I've got another video coming up soon which will include the BME280 and another one to show I2C communication option for these types of sensors. Stay tuned, and thank you for watching!
I used both Dht11 and dht22 sensors together, but dht11 sensor doesn't give the reading (I didn't use any resistor) when used separately both sensors are working fine. Can u pls help me?
can dht11 value represent as float like dht22? so the value have comma (,) like dht 13,7 etc
6 ปีที่แล้ว
Why keep working with the dht11/22, when you can get dht12/am2320 for the same prices or cheaper and you can choose between dht22onewire or standard I2C protocol
Thank you for your comment, the DHT11 is very cheap compared to all the others, for simple projects it might do the trick for some makers. But like you said there's better options if you need it. Thanks for watching!
6 ปีที่แล้ว +1
I apologise if my previous post was a bit too negative. I appreciate the effort that takes to create this kind of videos. Back to the sensors in question, a very simple search on AliExpress shows that the dht11/dht12/am2320/dht22/am2322 cost $0.68/$1.05/$1.43/$2.36/$2.66. At those prices there is no reason to pick a dht11 over the more versatile dht12. The same is valid for the dht22 vs am2320 or am2322. The dht12/am2320/am2322 can be read with the dht22 library, or via I2C. You would make a great service to your audience by introducing this equally cheep, more versatile sensors.
Hi guys, I have a problem with this line of code void loop() { int DHT11Check = DHT.read11(DHT11Pin); // I am having a problem on this line if (DHT11Check == 0){ Serial.print("Current Humidity = "); Serial.print(DHT.humidity); Serial.print("% "); Serial.print("Current Temperature = "); Serial.print(DHT.temperature); Serial.println("C "); delay(3000); } It says that DHT wasn't declared in this scope How do I resolve this problem? Thanks
I watch lots of Arduino videos. I am a High School Math and Science teacher. This was the best video I have seen in a long time. Short but loaded with details. Very well explained. Precise and to the point. Well done.
Very useful video and I have no NEST to compare.
I too got both DHT11 and DHT22 sensors and found massive difference in the humidity.
DHT11 sensed 51 while DHT22 sensed 77.
Exactly the information I need. I'm building a multi-roll filament dryer. It will have two fans inside and sense temperature and humidity at two locations inside, plus the outside air temperature and humidity.
Thanks! I'd like to see more sensor/component reviews, if possible. It sure saves me a lot of time! :)
Got a bunch of sensors/modules I haven't used yet, so when I find the time to try them out I'll make a tutorial about it :). Thanks for watching!
The issue with wire length and the pullup resistor is not wire resistance. You'd have to use a LOT of wire just to get one ohm. not enough to affect the reading. Especially since the output is digital.
The issue is noise. With a very high pullup resistor, like the internal pullup, it isn't very resistant to noise when compared to using a much lower resistance.
In any case, for that you should use twisted pair to reduce noise pickup.
I use only si7021. It uses I2C and is available as 3,3V version without regulator and works down to 1,9V
Thank you for your comment, in the next tutorial I will be showing 2 more temperature and humidity sensors that use I2C communications. Cheers!
If you don't need to measure humidity, a silicon diode will work as a temperature sensor. You'll just have to calibrate it, but that's not difficult.
Hi. Are you not making more Arduino tutorial videos? Newest video is 4 years old. I hope you come back to make more because I really like your videos and the info you put in them. In this case you show how to read a DHT and print to OLED but you also mention the DHT humidity is no good. I have not seen this in any other tutorial. Others only show how to read sensors but lack deeper knowledge that you seem to have. So I appreciate your videos very very much! Thanks for sharing this and I hope you will be back to teach us even more!
Comparing it to a nest sensor with unknown accuracy means you have 3 readings and cant say with certainty, which humidity reading is correct!
Thank you for the comment, of course there's no way of knowing which sensor is correct, but since the Nest and the DHT22 are showing very similar humidity readings compared to the DHT11... Thanks for watching!
@@BrainybitsCanada
That is still no indication that the nest is accurate just because one of the two sensors was closer than the other.
Best to have a calibrated sensor of some sort as well as taking multiple readings over multiple temperatures and humidity.
Some sensors wander more over a certain range.
An example could be an analogue speed dial display in a car.
It might be very accurate at 20 miles per hour. But get to 85mph and your actual speed is only 72mph.
Great job man
could you please send me the link to the thing where you explain the pull up resistor pls?? i had seen it and wondering how it works.
What the internal resistance of the cable would be significant compared to aprox 20k? Hence the on board pullup resistor?
When I piggyback a DHT22 sensor on the bottom of a 8266 D1 mini board to make it compact. The temperature displays 3-5°C higher immediately. Even with isolation foam between and the D1 mini not being warm at all, this stays the same. Once the sensor is 5cm away, all works fine. I’m wondering if this is some kind of interference. Now testing with the BME280 that seems a lot better and also has atmospheric pressure sensor. Thank you for making these videos.
Thank you for sharing your experience with the DHT22 sensor. I will be looking at the BME280 and another one in the next tutorial video. Thanks for watching!
Thanks for the vid, but a sample size of 1 barely makes a conclusion.
I should have to calibrate every unique dht11 or dht22 I use. Wouldnt a simple offset in your code at your average target temp make it much more accurate?
Thanks, excellent video. It I'll be interesting to compare bme280 sensor with dhtxx.
Got new videos coming soon, and the bme280 will be featured in one of them, stay tuned. Thanks for watching!
Simply - you bought DHT11 with faulty humidity sensor. I have a few DHT11 and DHT22 (also DHT21) and all of them give similar results. New DHT11 return temperature in with decimal digit. You are using old libraries which don't support DHT11 well.
Thank you for your comment. I've got quite a few DHT11 and they all give me off readings on the humidity. Maybe I got a bad batch? As for the decimal readings on a DHT11, it would not be very useful since the specs of a DHT11 indicates it's only precise to + or - 2 full degrees. Unlinke the DHT22 which is accurate to + or - 0.5 degrees. Thanks for watching!
I think in new DHT11 Chinese used different components. Because I still have 4y DHT11 which has broken humidity sensor and temperature is much less accurate. Regarding temperature - it is measured using thermistor inside as far as I remember. I will have to disassemble both old and new one and compare them.
@@cbm80amiga That could explain it, I've got those DHT11 quite a while back. Thanks for the reply. Cheers!
Thanks it helps a lot!
btw did you know how much is the maximum range for both sensor? (Because i wanna build project temperature sensor for room)
Check out the specs at 0:36
Very good vídeo, thanks. I just beginning on Arduino. I ask you, if I need to save the data, not using a display but just save the Data to Open on a excell. Can you made a video about that. Thanks
Nice and simple :) gj. Can you check new ones from Bosch BME280 and BME680? I got some fun readings from those 2 especialy if i use them with esp wi-fi boards. Tnx
I've got another video coming up soon which will include the BME280 and another one to show I2C communication option for these types of sensors. Stay tuned, and thank you for watching!
I used both Dht11 and dht22 sensors together, but dht11 sensor doesn't give the reading (I didn't use any resistor)
when used separately both sensors are working fine. Can u pls help me?
thanks, very helpful
can dht11 value represent as float like dht22? so the value have comma (,) like dht 13,7 etc
Why keep working with the dht11/22, when you can get dht12/am2320 for the same prices or cheaper and you can choose between dht22onewire or standard I2C protocol
Thank you for your comment, the DHT11 is very cheap compared to all the others, for simple projects it might do the trick for some makers. But like you said there's better options if you need it. Thanks for watching!
I apologise if my previous post was a bit too negative. I appreciate the effort that takes to create this kind of videos.
Back to the sensors in question, a very simple search on AliExpress shows that the dht11/dht12/am2320/dht22/am2322 cost $0.68/$1.05/$1.43/$2.36/$2.66. At those prices there is no reason to pick a dht11 over the more versatile dht12. The same is valid for the dht22 vs am2320 or am2322.
The dht12/am2320/am2322 can be read with the dht22 library, or via I2C. You would make a great service to your audience by introducing this equally cheep, more versatile sensors.
@ I'll have a tutorial video coming soon on the am2320 and another I2C temperature sensor. Thank you for your suggestion and comment.
5:06 "dht22 humidity sensor is actually worse"... What?....
Hi guys, I have a problem with this line of code
void loop() {
int DHT11Check = DHT.read11(DHT11Pin);
// I am having a problem on this line
if (DHT11Check == 0){
Serial.print("Current Humidity = ");
Serial.print(DHT.humidity);
Serial.print("% ");
Serial.print("Current Temperature = ");
Serial.print(DHT.temperature);
Serial.println("C ");
delay(3000);
}
It says that DHT wasn't declared in this scope
How do I resolve this problem? Thanks
how can I connect several DHT22 sensors to an raspberry pi?
more info on temp sensors for an Arduino project
th-cam.com/video/ynNeiFEJnrA/w-d-xo.html
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