Hello!
I'm currently building a controller for some CPU fans so that they only turn on once a command is sent to an Arudino microcontroller. The Arduino is powered by 5V via USB, and I have a 12V power supply connected to a breadboard. In addition, I have a 3 way switch to switch between off, automatic (arduino controlled), and manual on. Manual on bypasses the transistors and provides direct power to the other power rails on my breadboard.
I have a pin on my arduino connected to the base of a transistor with a 680 ohm resistor in series. I have the +12V connected to the collector of the transistor and then a line going from the emitter to the power rail of my breadboard.
The first version of this project worked completely off the USB 5V, however, there's insufficient current available via USB (500mA) for both the arduino and the fan to allow it to run at a reasonably high speed. I then connected up a 12V power supply and grounded the negative terminal the ground of the board and detatched the 5V+ from the board and replaced it with the 12V+.
I didn't have a heat issue with the transistors with the 5V version, but when I switched to the 12V, they get almost untouchable in seconds. They're 2N2222 NPN transistors. I've attached a schematic to the post, and if you want to see my circuit on the breadboard I'll attach that too.
It's also to note that in the initial 5V+ version, I unable to get enough current to drive the board, and when I added more transistors (up to 3) all sharing the same leads, I got better speeds. I continued this (thinking that it would allow me to transfer more current), but I still have massive heat issues.
Is a relay the best option here? I'd like to stay solid state but I don't know if I could design the circuit better and it'd work or I need to order some beefier transistors.
Any help or comments is very much appreciated!!!
I'm currently building a controller for some CPU fans so that they only turn on once a command is sent to an Arudino microcontroller. The Arduino is powered by 5V via USB, and I have a 12V power supply connected to a breadboard. In addition, I have a 3 way switch to switch between off, automatic (arduino controlled), and manual on. Manual on bypasses the transistors and provides direct power to the other power rails on my breadboard.
I have a pin on my arduino connected to the base of a transistor with a 680 ohm resistor in series. I have the +12V connected to the collector of the transistor and then a line going from the emitter to the power rail of my breadboard.
The first version of this project worked completely off the USB 5V, however, there's insufficient current available via USB (500mA) for both the arduino and the fan to allow it to run at a reasonably high speed. I then connected up a 12V power supply and grounded the negative terminal the ground of the board and detatched the 5V+ from the board and replaced it with the 12V+.
I didn't have a heat issue with the transistors with the 5V version, but when I switched to the 12V, they get almost untouchable in seconds. They're 2N2222 NPN transistors. I've attached a schematic to the post, and if you want to see my circuit on the breadboard I'll attach that too.
It's also to note that in the initial 5V+ version, I unable to get enough current to drive the board, and when I added more transistors (up to 3) all sharing the same leads, I got better speeds. I continued this (thinking that it would allow me to transfer more current), but I still have massive heat issues.
Is a relay the best option here? I'd like to stay solid state but I don't know if I could design the circuit better and it'd work or I need to order some beefier transistors.
Any help or comments is very much appreciated!!!