Lab power Supply
I am currently teaching a PCB Design course at my University (KTH). And the two previews years the students had to build a STM32 prototype board. The problem was that many of the students thought it was really hard to design the board layout, and there was not many that used the board afterwards. So for this year I changed the design so they should create a lab power supply. If you are going to study electronics you got to have a lab power supply. So I put forth three different solutions that the students could choice from, easy, hard, harder 🙂 . Easy is only a board with internal voltage reference and two potentiometers for voltage and current. And the two other has a STM32F3 Discovery board as a reference and controller, with the harder boards the user can set the voltage and current limit trough push buttons.
Specification of the “Harder” board.
- Current limit and voltage is set trough push buttons.
- Max 20v / 1.5 Amp based on how much cooling the regulator IC gets.
- LCD that displays voltage and current (in mV and mA resolution).
- Frequency counter that can sens 1mHz to 10 MHz, I will know the true max when i have the real board assembled.
- Frequency generator , set frequency and duty (PWM).
- Voltage and current sense is calibrated to avoid nonlinearity in the ADC.
- Settings are stored in flash. So when you reset/restart the unit it will have the same values and settings as before.
- and some more..
This way it is better, because now I have a better way to determent (and show) how good the student has designed the board. By noise measurement with static / oscillating load or no load the students will see how good their design is. And I suspect some boards will oscillate or in worst case burn. So the students will be faced with troubleshooting their own board. And if the student board works, I will introduce a fault so they have to troubleshot, which is the best way to see if they understand the inner workings of the design 🙂
LED Driver (Torch Controller)
I created a intelligent LED driver for my friend Marcus, his current project is to build a underwater torch light. The controller regulates the current to the led based on intensity setting and LED temperature. Most underwater torches are easy to break if you use it on land where the LED/Lamp will get overheated pretty quick. The controller can supply the led with 1.5Amp at most, I believe he is using the CREE MKR which is rated to 1665 lm at 15.25 W (12.2 V, 1250 mA). The first idea was to use the MCU to sense the voltage over the led when it’s turned off, and then use a PC screen to send command to the torch controller trough a PC program -> Screen -> LED -> MCU. But when we tested the idea it showed us that a standard LCD Screen did not affect the voltage out from the LED. but if we used a normal lamp or sunlight the LED supplied a few hundred mV, so that idea did not work. The board holds two switch regulators, one for the LED and one for the MCU. And the MCU can
also read the LED current.
The MCU is a STM32L151
Want to read more about Marcus underwater torch, click the link LINK
PCB Batch on the way back :)
I made a batch of totally 9 board that I have sent to seeedstudio for production.
Mostly the boards are for my PnP project, I was planing on waiting a few more weeks before sending the batch for production.
But i have to create the camera vision SW/HW function in quite a hurry because i took on the vision implementation as a curse project in school. So I desprately needed the light ring for the camera, aka lighthouse.
Solder Station v2 update
Finally I manage to have some time over so I could solder my new solder station pcb boards. There is still a lot to be done before i get
this one up and running as planned , but still this is progress!!
The housing is still under construction, i have finished all cad and cam files.
But there is still a few hours in the workshop left until the housing is
completed.
STM32 DevCard converted to an inductance meter
Needed a simple inductance meter when my regular one was missing.
So I made a simple one pretty fast.
I will see if I make a special PCB board for this later.
