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Add a quiet fan cooling system to existing equipment with this configurable controller.

I prefer a quiet and calm environment. It’s why I prefer listening to the more mellow broadcasts from BBC Radio 4 or Classic FM. It’s why I like full break-in CW on PIN diode rigs from Elecraft and Ten-Tec. It’s why I run a Mac Mini for macOS and a fanless industrial PC for Windows.

More often than not, equipment cooling and equipment noise go hand in hand. The more cooling required, the more airflow is needed and the more fan noise will be produced. However, fan choice and mounting options will help to mitigate this noise. As will a smart fan cooling system to control fan speed.

This project is an offshoot of a unit which was cobbled up with the objective of cooling communications kit in hot climates. A need to monitor and cool equipment whilst keeping the level of audible nuisance to a discreet level was required. It can be adapted to cool dummy loads, power supplies, computers, lighting…

Searching for a solution it was found that the cheap Chinese single board controllers available only provided a simplistic fan curve solution. These controllers just track temperature differences against fan speed. Not many parameters can be modified. On the other end of the scale there are complex cooling controller systems available for gaming computers, using PC software. These are fully configurable systems able to balance the cooling performance required against the generated sound level.

It was hard to find an intermediate solution. One between the simple stand alone boards and the complex systems used by PCs. So, an embedded system was conceived to fulfill my requirements. Starting simple and then building up the design based on specific needs. The project quickly dominoed to include some easily customisable features which can be setup for individual temperature and fan speed requirements.

- Two fan controller.
- Full fan speed control from 0% to 100% PWM.
- Temperature sensing from 0 to +120degC (32degF to 248degF).
- Fan speed tachometer reading to 9999 Revolutions Per Minute.
- OLED display showing fan and temperature information.
- Fan PWM commanded bargraph (10% intervals).
- Rotary encoder to manipulate configuration menu.
- Define temperature range, minimum to maximum.
- Define fan speed range, minimum to maximum.
- Three secondary Fan-B working options:
- a) Main Fan-A with secondary Fan-B running in tandem (Symmetric).
- b) Main Fan-A with secondary Fan-B running in opposite (Asymmetric).
- c) Main Fan-A with secondary Fan-B configured to Hot-Standby.
- Audible Fan-A failure or stoppage alarm.
- Luminous Fan-A stoppage alarm.
- Luminous DS18B20S sensor bus indicator LED.
- Luminous +12V and +5V power supply LEDs.
- Configuration settings saved in EEPROM, for power off recovery.
- Configuration header to set temperature units (degC or degF)
- Configuration header to set Symmetric, Assymetric or Hot-Standby mode.
- Isolated external P-Input, to enable/disable operation by auxiliary equipment.
- Main Fan-A failure detection, used to switch to Fan-B in Hot-Standby mode.
- Serial port for debugging and firmware uploading.
- In Circuit Serial Programming port for direct burning to memory.
- KF2510 3+1P, fan connector sockets.
- Easily accessible on board Reset switch.”

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