I've made this little project here https://hackernoon.com/raspberry-pi-temperature-controlled-fan-2aa0de72a564 to cool down my Pi3 which is running a bit hot during the summer. The only difference (or so i thought) was that i use a 5v mini fan instead of a 12v.
My setup is exactly the same, besides the use of an 2N3904 instead of the BC337 that he is using. I also use the same 1 kΩ resistor.
Everything was working fine until today, when i noticed the Transistor was getting hot every time the fan was on. I took a look at my transistors diagram and i noticed that the Emitter and Collector are reversed.
The BC337 has 1.Collector 2.Base 3.Emitter
while mine was 1.Emitter 2.Base 3.Collector
Immediately i shut down the circuit and here i am with a couple of questions
1) The max current the 2N3904 can take is 200mA, (same ammount as my fan), using the 1kΩ, i am down to 2.6mA [(3.3v-0.7)/1000], so that shouldnt be the problem switch the fan when the GPIO output is 16mA right ?
2) Should i use a small resistor like 180 ohms (to go up to 14.4mA) ?
3) I know its a silly question...but i should probably switch the Transistor right ? To match the collector/base/emitter specifications of the project.
4) Is it supposed to get hot ? I mean i must be doing something wrong right ? Should i just order a BC337 transistor and be done with it, or can i tweak my current setup somehow ?
I am programmer, not an elec. engineer so i am still learning here. I'd rather figure out why something is wrong than blindly follow instructions.
Thanks in advance.
-S
My setup is exactly the same, besides the use of an 2N3904 instead of the BC337 that he is using. I also use the same 1 kΩ resistor.
Everything was working fine until today, when i noticed the Transistor was getting hot every time the fan was on. I took a look at my transistors diagram and i noticed that the Emitter and Collector are reversed.
The BC337 has 1.Collector 2.Base 3.Emitter
while mine was 1.Emitter 2.Base 3.Collector
Immediately i shut down the circuit and here i am with a couple of questions
1) The max current the 2N3904 can take is 200mA, (same ammount as my fan), using the 1kΩ, i am down to 2.6mA [(3.3v-0.7)/1000], so that shouldnt be the problem switch the fan when the GPIO output is 16mA right ?
2) Should i use a small resistor like 180 ohms (to go up to 14.4mA) ?
3) I know its a silly question...but i should probably switch the Transistor right ? To match the collector/base/emitter specifications of the project.
4) Is it supposed to get hot ? I mean i must be doing something wrong right ? Should i just order a BC337 transistor and be done with it, or can i tweak my current setup somehow ?
I am programmer, not an elec. engineer so i am still learning here. I'd rather figure out why something is wrong than blindly follow instructions.
Thanks in advance.
-S