Just a short update on the 741 Op Amp Thermal Cooling Fan Controller. I must say I am quite impressed on how this simple little circuit/project is performing. Thus far it has run/operated perfectly. It keeps the Motorola Radio cool. Very little heat is present on the heat-sink even with long-winded conversations/broadcasts of more than 1 hour. I spoke to my brother in law OM Nico ZS4N over the weekend. He ran one of the fan controllers on the then Aliwal North repeater for more than 5 years without any problems. Today that very same controller is running in his Shack.
During a discussion on the SARL Forum mention was made of the LM358 Op Amp used in a thermal cooling fan controller project. Well I have decided to build the 358 fan controller. This fan controller also uses an output relay so it can basically switch/connect to any system to warn of an emergency, run as a fan controller, light source or sound device. I will start working on this fan controller soon and will provide feedback on its functionality.
I also intend to modify the current 741 Thermal Cooling Fan Controller currently used on the 145.550 Mhz link radio. The modifications will provide me with the following:
- Led indicator when the fan is running (RED)
- Led indicator when the fan is not running (GREEN)
- Install a variable 10K trim-pot that enables me to adjust when the fan must turn on at different temperatures.
Another option also in the back of my mind is to use a timer for fan control. I am going to connect the timer to the radios PTT for logic control and the timer will fire a relay that runs the fan. The fan will run while in TX and then 10 mins after last PTT. Underneath is the timer I will be using. More on this project in a future post.
Back to the workbench and lets see if I can build and modify the Thermal Cooling Fan Controller.
