InTheMail | Voltlog #321

Welcome to a new InTheMail, the series that will touch both your passion for electronics and your bank account at the same time. We have a selection of different items received in this mailbag, I’m gonna start with this GPS module, the model number for this is ZX612 and it’s part of the Chinese gps trackers family, I think it uses a similar protocol to the relay gps tracker that I showed in a previous video and possibly connect to the same Chinese web server for data collection which poses the usual privacy risks but as I’ve shown in Voltlog #274, using a raspberry pi you can setup your own gps tracking server.

Voltlog #246 – What if we install a heatsink on the TPS61088 boost module?

In the previous video where I took a closer look at the TPS61088, I did some measurements of the output noise but I also ran the module up to the maximum specified output power of 12V 2A. It was to be expected that the losses would turn into heat and just the small size of the board would not be enough to dissipate all that heat safely so the boost chip reached a toasty 150 degrees Celsius and inevitably went into thermal protection.

There were two questions that people mainly left in the comments of that video. First people were curious if this module would behave differently if a heatsink was installed and also some people thought about using this module in a fixed configuration, because if you remember there is a chip on this module that will switch the output voltage based on quick charge spec, depending on what the load is requesting through that protocol but people might just want a simple fixed output. To this I would add a third question of my own, what is the real efficiency figure of this module, at the maximum output. 

Voltlog #195 – Is Thermal Adhesive Tape Any Good?

Welcome to a new voltlog, today we’re gonna be testing and comparing thermally conductive double sided tape to other solutions like thermally conductive adhesive, silicone pads, or even regular double sided tape to see how effective these solutions are for transferring heat between an IC and the heatsink.

To produce the heat I’m gonna use a small analog electronic load circuit, which will be set for a certain current let’s say 200mA and in theory should produce the same amount of heat for each run. Then we’re going to insert the different type of materials between the heatsink and the IC and we’re gonna measure the temperature of the IC and the temperature of the heatsink. As you can see I have a thermocouple glued to one side of the heatsink with thermally conductive adhesive and another thermocouple glued to this TO247 style transistor that’s producing the heat.

I don’t have a particularly good way of testing this but my plan is to heat the transistor to a stable temperature while the heatsink is kept at room temperature. Then I’m gonna connect the two bodies and measure the time it takes for the heatsink to reach the same temperature or a certain value, close enough. Then repeat the test with a different material and compare the values. If that time span is shorter or longer will depend on the thermal resistance between the body of the transistor and the heatsink and that is highly dependent on the material used between them.