[Project][open source] Yet Another Linear Lab Power Supply - 0-24V 0-5A 100W - Page 1
Forum section: electronics / projects

author: nemail2
author_rank: Regular Contributor
timestamp: July 04, 2021, 12:17:24 am
content: HiThis is the n-th incarnation of my lab psu design which I started by copying and changing Dave's old µSupply project. Thanks to David Hess, T3sl4co1l, Zero999, IanB, xavier60, Kleinstein, bdunham7, Ian.B and many other folks here on the forum and on other platforms I finally came to a point with my lab PSU project where I'm quite happy with it.Sure, this thing has its flaws and it is nowhere near a professional Lab PSU but it is the very best I'm able to create and I'm happy with it as it isFeatures of this linear Lab PSU (no switching prereg, completely linear):- 0 - 24V in 1mV steps- 0 - 5A in 1mA steps- accuracy: pretty accurate :-D no idea how to characterize and measure everything properly- 100W max- 2x 12V 100VA toroidal transformer- Teensy 4.0 - virtually unlimited resources for going wild on software features- crystal clear, bright and crisp 128x64 2.7" OLED display- output relay (disconnects V+ and GND)- tap switching from this thread using a P-FET, no relay clickedy-action- dual BD139/TIP3055 darlington pair- active cooling for output stage with temperature monitored (PID) and PWM controlled 80mm fan- 2x TI DAC70501 14 bit with 5ppm internal reference for Voltage and Current setting- 2x ADS1115 16 bit ADC for voltage and current measurement- OPA4197 and OPA2197 precision opamps for control loop/gain stage- precision/low drift resistors for high initial and temperature-stable accurracy- 10 mOhm 15ppm 0.1% current shunt with LT6102 Precision Zero Drift Current Sense Amplifier for low heat generation and low voltage drop- Schottky diodes for voltage rectification to minimize voltage drop and heat- display as well as front panel diodes brightness is software-controllable- piezo buzzer- there is no ripple up until about 10.8V at full load (5A) with one winding and at up to 23V at 5A with two windings (IIRC, maybe a bit less).now imagine the possibilities if one would have time to go wild on the firmware... I have only implemented the very basic features for now.Everything has been hand-soldered by me, the case has been bought off the shelf (KRADEX Z17), front- and backpanel have been 3D printed by me, PCBs are from JLCPCB.Let me know what you think of it!

author: nemail2
author_rank: Regular Contributor
timestamp: July 04, 2021, 12:52:27 am
content: here's a closeup of the analog goodness and the teensy 4.0

author: Swake
author_rank: Frequent Contributor
timestamp: February 05, 2022, 04:55:08 pm
content: Nice work!Back in the schooldays, that was a veeeery long time ago, the first somewhat bigger thing to build was a decent power supply. The message was that you're not a qualified electronician as long as you haven't build your own power supply. The output of mine had a BD241 and a couple of 2N3055. Pretty similar to yours, I feel connectd.

author: ledtester
author_rank: Super Contributor
timestamp: February 05, 2022, 05:17:19 pm
content: Nice project!I have a question about the construction of your front panel... specifically how you implemented the spacers for the display board? Is the front panel 3d printed and the spacers are part of the 3d print?

author: nemail2
author_rank: Regular Contributor
timestamp: February 05, 2022, 06:13:43 pm
content: Quote from: ledtester on February 05, 2022, 05:17:19 pmThanks!the front panel is 3d printed, and the spacers are part of the 3d print, correct. i have as well printed a support bracket which goes between the display and the display PCB.see attached files for the STLs for everything 3D printed here (rename from txt to stl).

author: Sarvesaa
author_rank: Contributor
timestamp: August 04, 2022, 04:32:45 am
content: Quote from: nemail2 on July 04, 2021, 12:17:24 amOne is for voltage measurement.The other one is for temperature sensing right ?Isn't it.Thank you

author: nemail2
author_rank: Regular Contributor
timestamp: August 04, 2022, 05:38:06 am
content: Quote from: Sarvesaa on August 04, 2022, 04:32:45 amone is for current seinsing (ADC_CH0) and overcurrent, essentially CC/CV mode sensing (ADC_CH3) and the other one is for voltage sensing (ADC_CH2) and temperature sensing (TH0_ADC).

author: Sarvesaa
author_rank: Contributor
timestamp: August 04, 2022, 07:18:00 am
content: >Quote from: nemail2 on July 04, 2021, 12:17:24 amone is for current seinsing (ADC_CH0) and overcurrent, essentially CC/CV mode sensing (ADC_CH3) and the other one is for voltage sensing (ADC_CH2) and temperature sensing (TH0_ADC).Understood. I am a begineeer so thats why I didn't catch up quickly.I am an electronic hobbyist and I am going to join college within few weeks to get a degree in EE. So I want to utilize the vacation properly.I am also trying to build a lab bench power supply since it is a essential lab equipment.My specs0-24V0-1A not going to set the world on fire.1mV 1mA adjustment precision.1mV 1mA accuracyCan you help me with this. Can you explain about your circuit I understood only few concepts. It will be really helpful to me.

author: ledtester
author_rank: Super Contributor
timestamp: August 04, 2022, 07:32:32 am
content: Is the firmware source available?

author: nemail2
author_rank: Regular Contributor
timestamp: August 04, 2022, 08:26:26 am
content: Quote from: ledtester on August 04, 2022, 07:32:32 amcurrently the firmware is not really in a very releasable state, it is kind of hacked together and messy and not very well written.the most basic features all work (i'm using the device as my main lab PSU after all) but the hardware has so much more potential.I will eventually look through the code for major f***-ups and then release the source code but to be honest interest of the community in the project hasn't been too big and other stuff has taken precedence so that's why the project is stalling a bit.

author: nemail2
author_rank: Regular Contributor
timestamp: August 04, 2022, 08:33:14 am
content: Quote from: Sarvesaa on August 04, 2022, 07:18:00 amI have built something similar, 1A is quite easy to handle but 24V gives you challenges if you want to keep the design simple and straight-forward, because at low output voltages your power transistor has to burn all the input voltage down to say 0,1V. That'd be around (28V - 0,1V) * 1A = 27,9W to burn so take into account a big enough heatsink and some airflow. 28V is the rectified transformator voltage which needs to be higher 1) because of the voltage drop on your pass (power) transistor and 2) because of the voltage drop under full load. 28V may even be a bit tight if you take into account mains voltage variations.https://github.com/mamama1/LabPSU_CA1