CPU
Cooling Fan Tachometer standards
Also be sure to visit my article on changing the CPU fan to a more quieter one in this part of my site: CPU Fan Change.
There's not much on the internet about the rpm rotation sensor and it's specification. In addition to my page on changing the cpu cooling fan here, this page describes a little about the tachometer or rpm rotation sensor and it's electronics.
Firstly I decided to take apart the cpu cooling fan FD06010B1H that I replaced with a quieter one. Removing the magnets and coil, reveals a PCB with a chip.
This chip is a TO-92SP-4 all-in-one package that contains a hall effect sensor and coil driver circuit for a 2-phase DC motor.
The tacho signal also known as a FG signal is an open collector design and provides a square waveform output to the motherboard for determining the rpm of the motor. Most motherboards require a FG signal from the fan. The signal is always at TTL level through an open collector transistor.
To determine which standard a motherboard uses for the tacho signal, check the voltage across the pins on the motherboard fan socket; there should be 0v (ground- Black), +12v (power supply- Red), and +5v (Tacho signal- Yellow).
The +5v tacho voltage is through a pull up resistor and therefore requires an open collector transistor connected to it.
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Also be sure to visit my article on changing the CPU fan to a more quieter one in this part of my site: CPU Fan Change.
There's not much on the internet about the rpm rotation sensor and it's specification. In addition to my page on changing the cpu cooling fan here, this page describes a little about the tachometer or rpm rotation sensor and it's electronics.
Firstly I decided to take apart the cpu cooling fan FD06010B1H that I replaced with a quieter one. Removing the magnets and coil, reveals a PCB with a chip.
This chip is a TO-92SP-4 all-in-one package that contains a hall effect sensor and coil driver circuit for a 2-phase DC motor.
The tacho signal also known as a FG signal is an open collector design and provides a square waveform output to the motherboard for determining the rpm of the motor. Most motherboards require a FG signal from the fan. The signal is always at TTL level through an open collector transistor.
To determine which standard a motherboard uses for the tacho signal, check the voltage across the pins on the motherboard fan socket; there should be 0v (ground- Black), +12v (power supply- Red), and +5v (Tacho signal- Yellow).
The +5v tacho voltage is through a pull up resistor and therefore requires an open collector transistor connected to it.
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Open collector
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