BLOG #1 - Experimenting with Thermal Switches - motor is too hot

i haven't used a lot of thermal switches before although i did have a memorable incident on it. Many years ago, my brand new Philips blender stop working after i continuously use it for a minute or so. i thought it is spoilt. to my amazement it turns again after few minutes. i assume that there is some over temperature protection. Of course, there are other non thermal switch component that can serve almost the same purpose. I have also used over current protection to protect circuit, simple fuse and some IC does comes with over temperature and over current protection built in, especially when it comes to motor control. 

As i have some motor based projects on hand, my experiment is MAINLY on motor along with some relevant. i have a simple DIY dc motor driven weed cutter. it does have some problem. once it draws so much current until the on/off button melted. i have to change to a higher current ratings switch and thicker cable. it works, but after some time, my motor itself starts to burn (some of the carbon brush i believe). In short, it is interesting to use the experimenter kit along with the thermal measurement device to ramp up the current and experiment it, hopefully i won't kill too many motors 

Figure 1 my DIY weed cutter

Figure 2 DC motor

Figure 3 the new switch (which i salvage from power drill) and thicker cable

the second experiment is using DAQ card to connect with thermal couple to measure the temperature and time as i am running the circuit.

thirdly i have some small pcb heating elements (printed heater -> 2D and 3D) that has used to cause circuit malfunction of a protoype pcb board that i am doing as it drain too much current than what the dc-dc converter can supply. eventually i change to a higher current capable dc-dc converter but it has shortcoming like bigger inductor needed. the smaller current thermal switch (0.3A type) seems an interesting candidate to incoporate in such circuit

Equipments that i plan to use

1) thermal camera: 

although the experiment kit i receive doesn't contain a thermometer i plan to use a thermal camera for testing

2) battery

3) Keithley Source Measure Unit