Hello, I just received 5 LM35DZ temperature sensors. I was quite happy till I tested them and saw that the output voltage doesn't make sense. I powered them with 5 volts and the output is 4.14V in all of them. The temperature is around 20 degrees. As far as I know the Vout should be around 0.2V at this temperature(20*10mV).
Did I buy garbage or someone has any different idea?
Any chance that you mixed up the top view and bottom view of the TO-92 package?
Post a photo of your set up.
Does the voltage change when you warm the sensor between your fingers?
What did you use to measure the voltage? x10 Scope probe?
JC
the set up is the simplest as follows. Vs is 5v from arduino mega.
https://encrypted-tbn3.gstatic.c...
I measured de voltage with a multimeter and with arduino software using an analogic input. both readings are the same. I heated the sensor with my fingers but nothing changes.
I heated the sensor with my fingers but nothing changes.
Brutte, I don't understand your suggestion. Do you mean I should change the chip voltage reference? But the Vout shouldn't be 0,2V anyway?
The photo of your setup clearly indicates that you have swapped pin 1 with pin 3.
the set up is the simplest as follows. Vs is 5v from arduino mega.
https://encrypted-tbn3.gstatic.c...I measured de voltage with a multimeter and with arduino software using an analogic input. both readings are the same. I heated the sensor with my fingers but nothing changes.
Show us a Picture of your breadboard. A drawing of pinout is not helpfull. I also think you have swapped pin 1 and 3. Try to fix that.
Peter
today I bought an lm35 for 2 euro!! very expensive comparing with the ebay purchase of 5pcs for 3.5$!!
I connected it directly and reacted as it was supposed.
I swap the new with the olds... and the voltage is 0.2V with the new and 4.14V with the olds.
I heated the new sensor and works right.
I think I definitely bought a very chip garbage.... :-(
sorry for not posting the picture. With this info is proved that the connection was right.
4.14V with the olds.
I think I definitely bought a very chip garbage.... :-(
Bad luck. Sometimes there is little difference between cheap and cheat. :!:
I think Brutte could be right: a GP PNP would explain your Measurement.
Peter
http://upload.wikimedia.org/wiki...
According with the pin number of the image in the link and using the diode test:
negative to 1 and positive to 2=1.131V
negative to 1 and positive to 3=1.101V
negative to 2 and positive to 1=0.721V
negative to 2 and positive to 3=0.567V
negative to 3 and positive to 1=1.022V
negative to 3 and positive to 2=0.870V
I have hfe tool but... I don't have any idea how to use that.
Have you ever used an LM35DZ?what voltage should be measured at Vout pin for 20 ºC?
I have no idea what that device is. Not a BJT, not a MOSFET, not a JFET.
Did you initially test those with something that had limited current? Because if you applied 5V between emitter and base then these were BJT transistors.
Have you ever used an LM35DZ?
what voltage should be measured at Vout pin for 20 ºC?
Ok, thank you to all the helpers. Let's conclude...I received some devices labeled as LM35DZ that weren't LM35, and that was the reason why they didn't work.
End of story :-)
