r/electronics

From left to right:

Intel B8702A

Fujitsu MBM27C64

SGS M2716F1

Motorola MCM27A08

Mostek ET2716Q

Eurotechnique ET2716Q

SEEQ DQ27128

Intel QD2716

TI TMS2764

I read the different values on each tap in can capactor the get a single matching cap with equal or greater voltage and temp. Then set them as you see on a daughterboard, binding all grounds to a common ground post. Then run wiring to the appropiate terminal or junction of where that value capactor was in the circuit before. I find this way an efficient and orderly way to replace older multi-can capactors. The daughter board is attached to chassis by one or two small, "L" brackets.

Testing a .001 uf 6000v door knob capactor for leackage, both passed at least up to the 600v this IT-28 Capactor tester can run. Not the 2000 to 3000 volts that are possible in a SB-220 but it should be close enough if the "eye" does not close at 600v they should be good.

The old paper wound caps were replaced with new metal electrolitic caps, and bleed resister array which bleeds voltage off caps when unit is turned off. New metering board on the front of the power pack to feed readout meters on front panel. Older chokes and caps were removed from botyom grid circuit and the grid was grounded to chasis for better stability. A soft-key was built and added to the amp key up circuit to ne compatable with modern radios. Old coax and wiring replaced to higher temp and voltage rated material.

Dreading placing those SMDs… I need a PnP 😭

Rf choke replacement

Thought this might be interesting to some of you.
This is the inside of a failed Fuji Electric 6MBI75SS-120 IGBT module (1200 V / 75 A).
It’s quite impressive to see the number of aluminum bonding wires used to connect the dies to the power terminals.
The module was already dead, so I decided to open it up rather than throw it away.

After a lot of learning I finally designed and manufactured my own custom (working) PCB! it's an esp32s3 devboard, with as many sensors as you can think of: NFC, IMU, VOC, humidity/temperature, color/ambient light, magnetometer, microphone, speakers, sd card, I2C expansion. I'm a high school student, so this definitely took a lot of help from people who knew what they were doing, and two failed circuit boards before this lol.

Most recently I've used it for a rhythm game I made, where using the IMU let me make a beatsaber-style anime game of bad apple!

open source at https://github.com/darshg321/Ultisense

Wanted to try out these CH32V203 (144MHz RISC-V) chips for a while, so I've decided to make some nice USB gadgets for USB HID injection and just for studying the USB protocol. It has 2 leds and 4 captive touch buttons.

It fits nicely into a USB-A port and is very easy to carry around. And with it I've had tons of fun messing around with a bare-metal USB stack, and just in general learning the whole USB protocol.

It was really fun trying to make a bare-metal USB bootloader for this chip, but I've managed to fit everything in 2KiB. (Source here) For comparison the official bootloader is nearly 24KiB in size. As a bonus, I've also re-designed the V203 USB stack for ch32fun and sent in a pr :D

The PCB is also open source, check out the KiCAD files here: https://github.com/cheyao/comu (kicanvas)

I plan on just using them for HID injection and as a quick devboard when I need very few I/O pins (4 main ones, but I've exposed some more via testpoints)

(Name and form inspired by the *omu series)

This is the film speed selector resistor PCB used in the Canon New QL17 and QL17 G-III cameras (manufactured from 1969-1982). The construction of these is not that different from modern SMT thin-film chip resistors, with the main difference being that the termination is one-sided rather than wrapped around the edge of the ceramic substrate as it usually is now. They are approximately 2.5x1.2mm (0.1x0.05 inch). Later-production units of the same camera that I've worked on use the exact same design, but the size, placement, and soldering of the resistors tends to be more consistent.

This is the earliest use of surface-mount passive components that I have seen, in person or in photos, and it's likely among the first mass-produced consumer products to use surface-mount technology. The information available online about the history of surface-mount passive components is very spotty, but I was able to find what seems to be the first patent describing this style of thin-film resistor, from 1962 by an Italian inventor who apparently worked with Plessey in the UK. It's still unclear who was the first to actually commercialize surface-mount resistors - based on other patents from the time, thin-film resistor technology was well understood, but component manufacturers were largely focused on making through-hole parts, and patents for anything resembling modern surface-mount components would not start showing up until the 1970s. It would also be a while before SMT started appearing in more consumer products; even Canon's own A-series SLRs did not switch from through-hole to surface-mount passive components until the early 1980s.

i did combine 2 pcbs into one stencil but im not falling for this jlc

theyre probably gonna charge me extra or something

thats the production file.

they didnt care.

for some reason you guys INSISTED they would charge me more and downvoted my replys (why??) but i tried it and it worked out fine

maybe still draw on some traces between the designs but other than that you can indeed combine pcbs into one stencil in jlcpcb

The shelf is a 24 V tunable white/orange strip, with two anti-parallel strings, driven by an off the shelf controller. At full brightness it made a high pitched wine. Dimmed to a usable level, it got even worse!

Scoping the original controller’s output showed it drives the LEDs with a 2 kHz H-bridge waveform, and dimming inserts 0 V dwell that pumps energy into the harmonics right where your ear is most sensitive. A mic 5 cm away confirmed it, a harmonic comb spaced at 1999 Hz, with the 4 kHz member 16 dB louder when dimmed.

The replacement is an STM32 driving a three level H-bridge at 25 kHz through a proper gate driver, BLE control, on a 4 layer board sized to drop into the original enclosure.

Every harmonic now lands above the audible band. Current draw came out the same as the original, so the silence was basically free. It also remembers brightness and colour through power cuts, the F303 has no EEPROM so state gets debounced into a flash page.

Full writeup with the scope captures, audio FFTs and design files: https://github.com/AShadyPCB/led-shelf-controller

This is my first post documenting my transistor binary clock project. The goal is, to only use through hole transistors, diodes and passive components to form RTL or DTL logic. These logic elements should then divide the 50Hz mains into minutes and hours.

For this job, I designed T flip-flops, that can be reset. This would allow me to combine multiple T flip-flops and some logic, to count to any arbitrary number. The clock should then display this number using a few LEDs.

Today I achieved the first Milestone of this project, by soldering up the first PCB design and testing it. To my surprise, this design worked immediately! Now I am very happy with this first Layout :3

If I am done with this and I have documented everything, I am planning to open source the board and other files. No one would probably want to build a massive discrete transistor binary clock, that constantly draws 8 Watts, but whatever.

Now I can say: One PCB complete, 21 more to go...

Today, I had an issue where I checkled under the sink and noticed that the waste disposal had a very slow leak.
After tightening the seal, I decided to implement a home made moisture sensor and warning system.
It essetially detects water by passing electricity throught the water to the gate of a mosfet, and then using that mosfet to pull current through a dedicated LED flashing chip.
A small test button is included, to test the battery works, though I do not anticipate the batteries draining very quickly.
As such, only zinc cells were implemented.

This has given me a good chance to put the dedicated LED flasher chip to good use.
After checking online, I think it's been discontinued.
I initially wanted to use a high brightness 5mm transparent red LED, but it wouldn't fit into place, so decided on a 3mm LED instead.

The LED can be changed by inserting it into the female wire ends.

As for the sensor itself, just a small square of stripboard with interleaved probe terminals.
Simple, but gets the job done.

All installed with tape and hot glue gun, for fast removal, if needed.
All mounted on a small peirce of card, for a quick and dirty job.

Today’s fun SMD soldering rework under the microscope. Tossed the penny in there for scale 🤓