Be COOL my little friend....

As I sit here writing this, I am pondering my nasty cold that was a gift from my son-in-law.  The nasty Cold is a segway to keeping cool.  Not much of a lead-in, but I'm not 100% on my game right now anyway.

Today I would like to briefly mention the amazing little known and easy to use KSD9700 Thermal Switch.  Doesn't that sound SOOOOO exciting??!!

Actually, when you have an application for these little switches, you will be very excited. So let's just do a brief summary of what we are talking about.

Many of us have switches on the brain.  We have relays, transistors switches, switches operating from light sources, verbal switches that operate by voice commands to a Smart Home device, and on and on.  Once in a while, you need a switch to manage heat and cold.  This is when a thermal switch comes into play.

KSD 9700 Thermal Switches 

So here are some KSD 9700 thermal switches.  They are versatile and come with two main features.  

1) the operating or actuation temperature

2) the operating condition (i.e. normally open or normally closed)

The operating temperature ranges from 40 degrees C to 130 degrees C, and maybe even higher.  That means that once the operating temperature is reached inside the switch, then the switch will throw to its closed position, or the other way around depending on whether you buy a normally opened or normally closed switch.  READ on...

The operating condition is simply whether the two leads are in continuity normally (normally closed), or not in continuity (normally open).

Practically speaking let's say you have a fan that you want to come on at 40 C.  So you buy a 40 degree C switch that is normally open.  The switch then goes in series in the circuit from the power supply to the fan.  When it goes over 40 C, the switch goes to the closed position, and then electricity flows to the fan.

Each one of us who has even a minimal imagination can come up with many uses for a switch like this.  Consider your computer, or your Raspberry Pi, or some other device.  You can set up a fan to run only when the temperature limit is breached.

You can also think of situations where you want a device to run until the temperature rises and then you want to stop.  Or perhaps you want something to run when it gets too cold.

In my shack, I have a particular purpose for this versatile little switch.  I cannot stand the sound of the fan that I have installed in my homebrew amplifier running all the time.  So, I can use one of these switches to sense the heat of the heat sink close to the rf finals.  Over a certain temperature, the fan will kick on until the temp cools.  This way I don't have constant fan noise.

Another use might be in the field when you are in warm conditions and you need to keep certain gear cool.  At the same time, you have limited battery power, so you only want to run the fan when you must.  The thermal switch will then decide for you when to flick the fan on or off.

I am intrigued to know what use for which you might consider using such a thermal switch.  Please send me your ideas.  I would love to hear what applications you can dream up.

73 Mark 4x1ks