Hello
I'm trying to modify a CO2 circuit, using a K33 ELG (CO2 sensor) from SenseAir and a small 12V Radial blower.
I've been using the original setup (see attached), with some alterations. In in the original setup a blower was present, I tried to add a blower, which could turn on and off by the help of a transistor.
However, my blower is turned on all the time, and I register approximately 9-10V running through it at all time.
After reviewing my schematics, I assumed it was because of the K33 ELG sensor which was hooked up to VIN through a 10K and 20K resistor.
At the moment I've tried to solved the problem by just writing a simple code to turn on an off the transistor
void setup() {
// initialize digital pin LED_BUILTIN as an output.
pinMode(7, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(7, HIGH);
delay(10000); // wait for 10 seconds
digitalWrite(7, LOW);
delay(10000); // wait for 10 seconds
}
I've tried isolating the problem by only supplying GND to the transistor, however with no luck.
My question is first of all, why is GND connected (through resistors) to the VIN, and is there a way I can turn the blower on and off anyways?
Parts information:
CO2 sensor K33 ELG SenseAir (link: K33 ELG | Senseair)
Powering sensor via Vbat+ 5.5-12 VDC
Current consumption: 250 µA (1 measurement/hour), 50 µA in sleep, 60mA average during active measurement sequence, <15 mA peak current, <250 mA on startup.
Radial blower (link https://docs.rs-online.com/704f/0900766b815de75f.pdf):
Nominal voltage: 12 VDC
Nominal current: 0.045 A
Rated power: 0.84 W
NPN Transistor BC337 (link: https://www.elfadistrelec.dk/Web/Downloads/_p/df/Diotec-BC337-16BK_eng_ger_tds.pdf)
Collector current: 800 mA
Much appreciated!
Jonas
