Reddit:Electronics

Man the difference between linear and logarithmic pots and faders for volume is pretty interesting.

This is my third TX-6 style mixer that I had time to finally finish. The first used linear faders and pots, and the second had faders that were too high value resistance so it was more on the quiet side.

maybe it's time to start using PCBs

For more detail: https://blog.mehmetasaf.me/how-to-build-a-uart-to-half-duplex-converter-for-your-servo-projects/

Tomorrow, I will build this schematic on a breadboard. I might add some pictures later. Thanks for reading.

I have designed and built a test jig that will automatically test a small USB output for bench power supplies adapter called USBpwrME. The USBpwrME allows users to connect USB powered electronics to a power supply during test, evaluation troubleshooting etc.

Test jig in action

The test jig is built around the PIC18F27K22. This is my goto chip at the moment. It has a lot of configurable peripherals, ADC with really high resolution and a huge amount of memory for being a small MCU. And wide supply voltage range!

Test sequence will cover all the functions of the USB adapter with as few operator interactions as possible. One "funny" mistake i made during the design was not noticing that the relays i use has actually polarized coil so the pos/neg has to be connected in correct way to make the relay click. I missed this so i needed to hand modify all three relays.

Second mistake i made was actually a bit harder to foresee. One test that is performed is to invert the the input polarity to the USBpwrME to see that the polarity protection works. Well the design mistake was that the GND between the jig and the adapter is connected together thru the GND shield of the USB cables. So when the polarity switches the test jig short-circuits itself and restarts.

I solved this by adding in the test sequence when to actually connect the USB cables and performing the polarity test just before.

Even my eight year old son can operate it :) :)

Quite happy although with the result

Of course, the process was not completely smooth. I wanted to add reverse polarity protection to V1, which the prototype did not have. In the first design, I built and tested a reverse polarity protection circuit with a single P-Channel MOSFET. However, I had missed one scenario: although a single P-Channel MOSFET can be enough in some cases, it could not block reverse current coming from inside the device. Even when the IRFP260N MOSFETs were off, reverse current could pass through the body diodes and put the connected power supply into a short-circuit condition. To solve this problem, I reworked the PCB to convert the power input block to a back-to-back P-Channel MOSFET structure. I used the banana sockets on the front panel as the protected input, designed to support an 8-30V range. The XT60 connector on the right works as the unprotected input and supports a 0-30V input range. After the rework, the protected power input caused significant heating at 8V and below because it left the protection MOSFETs partially on. For the next PCB revision, I plan to redesign the power input block using an ideal diode controller and two low-RDS(on) N-Channel MOSFETs in a back-to-back structure. Also, because of the two P-Channel back-to-back MOSFETs, the protection MOSFETs heated to unsafe levels at my target 200W test power. For safe operation, I limited the device to 150W. The device can support voltage and current values up to 30V and 10A within this limit. On the software side, with AI assistance, I developed control, protection and monitoring functions such as toggling load draw with the RST button, overcurrent warning, reverse polarity notification, temperature tracking and fan control. For the V2 revision, I aim to improve the device with more functional features and design a structure with higher power capacity. Overall, this project was a very educational and experience-building work for me in power electronics, measurement, PCB design, mechanical design, rework and fault analysis.

https://omerikinci.github.io/projects/electronic-dummy-load.html

Kept redoing the same impedance calculations during SI work, so I built this into a proper tool.

It covers: Microstrip, Stripline, Coaxial, CPW, GCPW, Differential Pair — gives you Z₀, εeff, propagation delay, loss, VSWR, Smith Chart, dispersion analysis, and parametric heatmaps.

Runs in browser, no login, no account.

Link: tools.vyomex.in/Impedance_calculator

Happy to hear if anything is off or if there are topologies you'd want added.

VSDSquadron FPGA Trainer Kit for High School Chip Design is now ready to ship — a complete hands-on platform to learn RISC-V, FPGA, and real chip design from school level.

Man one month of waiting for the pcb only for me to fuck up the footprint, what a jolly...

Bought a 24GHz radar module to tinker with and, after a few tests and experiments, ended up designing this board to make further testing a bit easier with the eventual aim of designing my own radar system or close!

Has been a really enjoyable learning experience so far. Time to start writing some 1’s and 0’s now!

So this is my latest draft for a railsplitter with low noise that is ment to be an accessorie fir my 60V 5A power supply. You could add 1uF film+100nF ceramic between Q5 and Q6 Collectors, and 100pF on Q1 base to Q1 emitter for lower transients and risk for oscillation. If you parallel 2 tip35c + tip36c you could go around 8-10A unbalanced load with propper cooling. As long as the load is symmetrical then this circuit should be able to handle several amps (Atleast 10A). It might be hard to see but i added a 1000uF 80v electrolytic capacitor 1 uF film 100v and 100 nF ceramic 100V at the input for more stability. Can't say for sure that this works like it's intended as i haven't simulated or built it yet, I just now finnished the schematic, will post the results once i am finnished with it. If it works like intended then it could be a good way to be able to run amplifiers using single rail PSU. And the Voltage/Ampers is limited by what components you use. If you switch the small signal bjt's/drivers to over 100V+ and use mosfets as power stage you could theoretically drive ±50V and 50+ Amps.

A really good space for me and my projects.

Worth noticing is the home made ESD gun that can deliver 7-8kV discharge, and a really primitive compressed air tank made of an old fire extinguisher connected to a small airbrush compressor. Perfect since it's non oil tech. Use it mainly for my hot air soldering station. Below the blue compressor there is a homemade heat chamber for temperature tests. Really bad pic but it can be seen on the overview picture. Also my latest project that i'm working on, that i have named USBpwrMe connected to the bench power supply output. Enjoy :):)

Hello everyone! About 2 months ago on a whim I ordered 6x of these IV-11 VFD tubes from eBay, and decided I wanted to design and build my very own VFD tube clock! After getting good tips and feedback on reddit, prototyping everything on a breadboard, designing a custom PCB, and soldering it all together, here's the finished result! This is my first real personal project as a new EE major and I'm thrilled with how it turned out.

The clock runs on an Arduino Nano Every with 6x daisy-chained 74HC595 shift registers and UDN2981A high-voltage source drivers, one pair per tube. The anode and grid rails run at 25V from a boost converter, and the filament runs at 1.5V from a buck converter, all from a single 5V USB supply.

A full writeup covering design decisions, schematic, and PCB layout is on my GitHub Repo. Stars are appreciated! :)

Work in progress! I was inspired by numerous #Minecraft inspired IRL compass and the fact i could not buy it was the driving force to develop one.

The needle animation works fine; it is the first step in order to make the final product.

I built it from ground up (Custom LED matrix, 3d printed housing), if anyone needs more details on the hardware or anything related to the project feel free to comment and ask away.

P.S. It is still a prototype so it's a little a little janky and the custom PCB is held by some tape.

I designed DC spot welder controller up to 4kA+ which can be powered from high current source or extrenal 12VDC source. I want to setup it with 4s or 2p2s LEV40 pack.

If it passes the tests I will make it open-source.

Functions:

- Settable amount of energy into the weld in reasonable time with 50us control loop

- Autopulse with settable delay for example pulse will be send after 300ms after shorting electrodes

- Manual trigger (no delay)

- Measuring source voltage

- And maybe others

Made a simple online tool for minimizing Boolean logic: https://www.logic-solve.com/

Drop in a truth table or PLA and it gives you the optimized version along with Verilog/VHDL/C output and a K-map view. Runs locally in the browser for smaller designs.

Figured it might be useful for some of you working on digital stuff. Especially folks working with hardcore, transistor or relais computers. With this you can minify your designs.

For more detail: https://blog.mehmetasaf.me/bts7960/