Dilshan R Jayakody’s Web Log

A few years back I purchased Honeywell CL15AE evaporative air cooler and it is15L indoor air cooler manufactured by JMATEK (for Honeywell). Sine last week this cooler became dead, and the only thing which I can see live is its red color power indicator. After disassembling the unit I see that most of the components of the controller PCB are rusted and damaged.  As I observed the main reason for corrosion is the absence of protective varnish on the top side of the PCB. The original control board of CL15AE cooler. At first, I restore all the damaged parts in the PCB with new parts, which including SS8050 , SS8550 , transistors and a few of electrolytic capacitors. After replacing those components, the unit starts to beep during power up but failed to power on. Damaged SS8050 and SS8550 transistors. After some tests, I figured out the problem is in SONiX SN8P2602 8-bit microcontroller.  Due to unavailability of microcontroller and it's firmware I decided to pr...

In this post, we describe the fan controller which we designed for our 9U wall mount server cabinet. This fan controller is designed to drive a 12V DC cooler fan with pre-configured intervals or by monitoring the temperature of the server cabinet. The final version of the fan controller with DC brushless fan and 12V - 60W PSU. Core components of this fan controller are CD4060 binary counter, LM35 temperature sensor, and LM358 operational amplifier. In this design, CD4060 has used as long duration timer and it can be configured to trigger cooler fan from 1-minute and up to 4-hour. In this design, an LM35 temperature sensor is used to activate cooler fan in specified temperature. This sensor stage is useful to drive cooler fan when timer stage is in an inactive state. To control the cooler fan we use AP9971 dual N-channel power MOSFET transistor. We design this system to drive 12V cooler fans up to 2A of current. To test this controller we use commonly available 120mm × 120mm...