Category: DIY

This category will hold everything DIY related.

Upgrading Workbench Lights Using 7020 White LED Strips

Although the operating temperature of this LED might be up to 85 deg C, while looking through various datasheets, I couldn’t find a graph showing a plot of the expected life in hours vs temperature. If I were to guess I would say you need to run these at less than 50 degrees C to get some decent life out of them. There was a mention of a stress test in a datasheet and that meant for that particular led manufacturer running it at 60 degrees C full rated current for 1000 hours with no resulting damage.

If you have any info on these LED’s and what temperature they should be running at to get some decent life out of them, please leave a comment below.

So to finish up on this story I have to say that I learned some things about these LED strips. If I were to design something from  scratch I would run some basic thermal calculations based on the figures from datasheets but in this case, with these chinese led strips, there is no datasheet, I can’t even easily compare to existing datasheet because these can’t be compared: the driving current is different, the LED only has one die in my case and so on.

The next thing I will try is to double my L shaped heatsink with another piece the same model and size this way I will be increasing my heatsink surface and hopefully cool the LED’s better, maybe shave another 5 degrees.

I will be posting an update with some measurements for comparison once I get the upgrade done. Links for the power supply, led dimmers as well as the light meter used in this video will be in the description of the video so do check them out.

VoltLog #16 – Laptop battery teardown and lithium cell recovery

Today we’re going to be looking at some laptop batteries, we’re going to take them apart and attempt to salvage some lithium cells to use in other projects.

I have these two identical batteries coming from a Fujitsu Siemens laptop and they’re both dead. These batteries usually fail in one of two modes, they either have a failed electronics board and in this case they don’t communicate with the laptop motherboard anymore for correct management or they have one or more lithium cells failed and they don’t reach their nominal voltage anymore.I believe these two are in the second category where one or more cells have failed and they don’t reach their nominal voltage anymore.

Voltlog #15 – Kit Assembly LED Rotating Persistence of Vision Kit

The assembly of this LED persistence of vision kit started well but it soon went bad because of poor design and lack of instructions. There is no documentation on how to assemble the mechanical parts so you have to figure that out yourself. There is no mention or pictures of how the LED’s should be soldered and to my surprise they need to be soldered on the edge of the PCB. There is no information on how to load the firmware or custom text patterns. After some research I did manage to find a chinese app which is supposed to work with this kit but I had no success in writing/uploading anything to the microcontroller.

I even spent an hour or so with google translate and, translated to english most of the buttons and messages in the app.

At this point I’m not sure if my problem is in the hardware(unlikely) or if I need to program the microcontroller, or if the microcontroller has some firmware and I just need to upload a custom display pattern using that chinese app.

Too much time & effort has been wasted so I’m not going to follow this anymore. My recommendation: don’t buy this kit unless you have too much free time and you enjoy solving complicated (chinese) problems.

VoltLog #10 – HP 3478A Line Voltage and Frequency Adjustment 110V 60Hz to 230V 50Hz

In this video I am switching my HP 3478A from 120V 60Hz AC to 230V 50Hz AC using the internal selection. I am also comparing some voltage and resistance measurements to my Keithley 175 and I realize the HP needs calibration if I am to trust it’s measurements. While I was inside the meter I also checked the voltage of the internal battery used to store calibration data.

VoltLog #8 – Kit Assembly 0-30V 0-3A Adjustable Linear Power Supply

In this video I am assembling a 0-30V 0-3A Adjustable Linear Power Supply kit. Will it work at first power on? Or will Murphy get me this time? Watch the video and see how I got myself into trouble. I also reverse engineered and got a schematic of this kit which I am showing towards the end of the video.