Hello all,
I’ve just bought a GSR Grove sensor, 1.2V.
I’m a bit puzzled about how the potentiometer works, basically no matters how I screw/unscrew it, the output remains the same.
Since it has not a dead end, I’m wondering how are we supposed to take a reference. Is there a way to measure with a multimeter its output? How is supposed to change the Resistance value of R1? Will be the variation between 0 to 100K as I expect?
Thanks for your feedback,
Antonio
Dear Customer:
I have got your question. You can measure the potentiometer with a multimeter under no power supply. Here is the Grove GSR seneor’s wiki(http://wiki.seeedstudio.com/Grove-GSR_Sensor/).At the bottom of it ,there is a Grove-GSR v1.2 Sch that can help you understand how potentiometer works.
Best Wishes!
So accordingly to the schematic I was able to measure the resistance of the Potentiometer between R3 (left hand side of DNP) and GND.
Value of the resistance goes between “open circuit” ~ 0 and 101.7 (accuracy of the multimeter I use is ± 1% +4.
The reason why I wanted to conduct that measurement was because I’m having a similar issue reported here:
<URL url="https://forum7.seeedstudio.com/t/grove-gsr-sensor-v1-2-cannot-adjust-resistor-to-512/5784/5 text=“viewtopic.php?f=17&t=7666&p=26566&hilit=gsr#p26566”>https://forum7.seeedstudio.com/t/grove-gsr-sensor-v1-2-cannot-adjust-resistor-to-512/5784/5
According to the schematics, Resistance offered by the Potentiometer is supposed to be 200K (R1) but the value measured is way too far from it.
I believe the Potentiometer is broken … does it need to be replaced?
Dear Costumer:
I used a GSR sensor to test it’s wiki again, and I didn’t find any problem. I have several suggestions for your reference.Hope can help you.
1.Switch needs to be turned to 5V.
2.The sensor need to be connected to A0 Grove.
3.In the wiki’s step2,you can also disconnect finger sleeve with GSR.
The GSR is a simple sensor ,it just have a LM324 and several resistances and capacitances.Potentiometer is fragile when you rotate it frequently. I don’t know if your potentiometer is broken.Maybe you can use a new one to test again.God bless you！
The GSR is a simple sensor ,it just have a LM324 and several resistances and capacitances.Potentiometer is fragile when you rotate it frequently. I don’t know if your potentiometer is broken.Maybe you can use a new one to test again.God bless you！
Then you have a design problem. If the potentiometer breaks up because of turning the screw too much you have to have it done with a more reliable component.
There’s no way to have another potentiometer added to the circuit, as everything is at the level of microelectronic. And, on top of that, as a customer I don’t have to repair something that is brand new and it’s sold as working.
Dear Costumer：
I’m sorry to let you have a bad experience.Actually,the probability of malfunction of the potentiometer is very low .I will write down your suggestions，thank you!
Dear Customer，
We went through the schematic and tested it physically and it is around 101ohm. because the point we measured is combined by 2 Parallel resistors. one is 200kohm and the other is 204.7kohm(200kohm+4.7kohm). Here is the schematic. So the measurement is right, it is 101.16Kohm.
For the calibration, please follow below steps.
Step 1. Please connect it to A0 port of seeeduino and download the code from wiki. http://wiki.seeedstudio.com/Grove-GSR_Sensor/
Step 2. Do not Wear the GSR sensor.
Step 3. Click the Tools-> Serial Plotter from Arduino IDE
Step 4. Use the screw driver to adjust resistor until the serial output as 512. this step will take sometime to adjust.
Step 5. Then Wear the GSR sensor.
Seeed techsupport team
Bill