DIY coffee mug warmer

In my introduction post I told that, once in a while, I'm gonna post a DIY post. Up until now, I've been blabbering about everything and anything, but now, the time has come for me to post the first DIY post. So, here it goes!

A few months ago, I found out at my workplace that there are a lot of obsolete (and mostly malfunctional) computers piled to be thrown to the junkyard. I sniffed around and found a few 1999 Intel Pentium CPU's that were still working (by working, I mean that they started "ticking" when being given the voltage supply).

At that time, I saw a few posts on some obscure forums about mug warmers based on old processors (something like this: https://brtb.wordpress.com/2010/07/16/usb-powered-cpu-based-cup-warmer-heat-up-the-plate/), so I decided to give it a go. I pulled out a few functioning CPU's to try and warm a cup of coffee or tea with them, and also a few old CD-ROM drive enclosures and power supply grills to make an enclosure for the mug warmer.

I decided to supply the CPU via USB port. It is possible because both USB 2.0 and 3.0 ports can supply a device with a voltage of 5 V and with a current of 500 mA (USB 2.0) and 900 mA (USB 3.0). That means that USB ports can give 2.5 W (2.0) or 4.5 W (3.0) of power to the CPU. So I connected the CPU's power supply pins via USB cable to the USB port and started checking how hot can the processor become. Of course, one mustn't forget to put the shunt resistor between the USB port and the CPU to limit the current to 500 mA (or 900 mA if you're working with USB 3.0).

After I'd seen for myself that the CPU can become hot enough for the people not to be able to touch it with fingers, I made an enclosure for the CPU mug warmer from the CD-ROM drive enclosure and I used an old power supply grill for the mug holder. I glued the CPU to the bottom side of the grill with epoxy glue and I screwed the grill to the modified CD-ROM drive enclosure. I also added a little switch and an indicating LED just to make it look more professional and I also painted the enclosure to black and you can see the final product in the picture above.

I have to say, although it does look cool and it sound like a good idea, this thing is not very efficient. And because the power supplied to the CPU is very small, boiling the water would last for infinity! So this thing can be used just to keep the temperature of your beverage at the acceptable level, and also, to do that, your mug should be made of tin (or some other metal) and not of ceramics (because metals are heat conductors, while ceramics is a heat isolator).

So, while it is a cool project to do, don't think you could sell it or use it instead of regular water heater or beverage warmers or something like that. But if you want to jerk around a bit with a solder and an old CPU, go for it! :)

That's it for today. Did you do anything similar? Do you have an idea how to upgrade and improve it? Let me know your ideas and/or comments.

Cheers boys and girls! I'll be back!

Pero

P.S. Here's another picture of the DIY mug warmer. :)