I previously used a magnifier for soldering 100um parts but am having a difficult time finding what type of magnifier product it was. From what I remember, it had a rectangular screen/glass that you would look straight into similar to a microscope but it was just one large eyepiece instead of the standard two. I also think the eyepiece was vertical instead of the standard horizontal or angled that microscopes have but I can't be sure. It did have lights and I think a dial adjust the distance from the eyepiece to the object. I would be grateful for any help in tracking down what type of magnifier or tool this is. It was very useful for working with small objects and I definitely want to buy it!

I would like to take up a project in which I wire rechargeable batteries in parallel in order to create a portable phone charger. Partly because I don’t want to buy one, and also because I want experience in electrical engineering. I am looking into cheap ways to buy/recycle lithium ion batteries to do this. Is there any suggestions on how I can do this without spending a lot of money?

This is a bidirectional voltage level translator with 1 circuit and 8 channels, capable of 60Mbps, in a 20-VQFN package. According to the datasheet, VCCA and VCCB should be connected to different voltage levels. However, in the circuit shown below, both VCCA and VCCB are connected to the same voltage.

Fig: Voltage Level Translator

Can anyone explain the purpose of using this configuration? What is the specific use case for this setup?

Datasheet Link: https://www.ti.com/lit/ds/symlink/txs0108e.pdf?ts=1732258880964

Hi i have been working in electronics since 8 years, but i have a question , how come some engineers design the schematic and pcb without hesitation, i see you tube videos and pictures of product they make, then everytime i think, how do they do it, where are the product requirement, where are calculation? how come they design without calculation of power and all, eveytime i again start my study again and again from diode, they bjt and mosfet. its like its a constant loop of learning same thing again, at least for me . and completion of project is also a major stage, people just go off with designing and deliverying and i feel stuck ad stages in between and timeline just crunches. anyone feel this way? . i try to understand each little bit of design , but engineers i see online etc just goes off without it. am i approaching wrong ?

tl;dr; how do I connect USB+, USB-, and USB VCC to this device? https://imgur.com/a/c0y94jL

I'm just coming back to electronics after a long time and so am sort of starting from near scratch with my understanding of everything. That said, I'm designing a PCB for a small ESP32 based art project I'm building. I am trying to find the sweat spot between "read the datasheets and really understand everything" and "copy/paste from other designs from people who know a lot more than you"

Along those lines, it seems that including some form of ESD, while not strictly required, is a good practice, so I wanted to do this. BUT, this is a situation where I decided to sort of blindly copy from a schematic / part I saw somebody use in a youtube tutorial.

For that reason, my "rev 1" PCB I just printed uses this part: https://www.digikey.jp/en/products/detail/onsemi/esd7104mutag/2797163 - I'm using a hot plate to solder everything, and actually the first board I made this part seemed to solder just fine and the part works - BUT, I realize it's a real pain in the ass if I had to try to hand solder this thing for example. So I'm thinking in my second revision I would use a different IC that I could actually access the pins, and I was thinking about this one:

(tl;dr; image: https://imgur.com/a/c0y94jL )

https://www.digikey.jp/en/products/detail/stmicroelectronics/ESDA6V1BC6/1037985 (datasheet: https://www.st.com/content/ccc/resource/technical/document/datasheet/21/07/21/e3/a8/df/42/a2/CD00001906.pdf/files/CD00001906.pdf/jcr:content/translations/en.CD00001906.pdf)

The problem is even having read the datasheet (or as much as I can), I'm not actually sure how this thing works. The current design I have, copied from youtube video, looks like this: https://imgur.com/a/cLNOeVi - USB +, USB -, and VCC from USB connect through the IC. I don't know how this works, but more importantly (for laziness) I don't know how this might work with the other device I'm considering.

Finally, if anybody is able to tell me if this device will actually work for what I'm doing that would be amazing. In short, my device will potentially be handled by people and will be located outside (in an enclosure, but during the summer and winter).

Thanks for any advice / help / etc!

Hi everyone,

I'm working on a battery-powered embedded design where the MCU requires a safe shutdown process. To ensure this, I've included a low-capacity backup battery in the design. I'm using a power MUX to switch from the main battery to the backup battery when the main battery is removed or dies, allowing the MCU to complete its safe shutdown.

The goal is for the backup battery to provide power just long enough—around 30 seconds—for the shutdown process to finish. I’ve brainstormed a few approaches but wanted to see if anyone has better or more complete suggestions. Here’s what I’m considering so far:

1. Using an MCU GPIO to control a FET that disconnects the backup battery after the shutdown is complete. However, this has some obvious challenges, such as ensuring the GPIO can reliably trigger the FET at the right time.
2. Using a timer circuit (e.g., a 555 timer) to control the FET after a set interval. This option isn’t ideal due to space constraints and potential long-term timing drift caused by capacitor degradation.
3. Using a simple and inexpensive secondary MCU dedicated to managing the backup battery cutoff. While this would work, it adds some complexity and cost.

Ideally, I’d love to find a power MUX or similar component with a built-in timer function to automatically cut the backup supply after a programmable time interval, but I haven’t come across anything like that yet.

I’d appreciate any suggestions for components, approaches, or fresh ideas. Thanks in advance for your input!

I got this external dual bay disk enclosure from Aliex and it has two blue LEDs for disk activity, one for each disk

I'd like to replace one LED for other with another color

Besides the SMT soldering, what should I take into account before changing the LED?

Component size seems to be obvious. Resistors, other components,, maybe?

Thanks

Hello all, I am trying to figure out the topology of a circuit to provide 3.3v outputs with two inputs: a 5v2A USB port, and a 3.7V LiPo cell.

These are my requirements:

1. I need the USB port to take priority over the battery, that is, the USB port will take all the load if its plugged in, as well as charging the LiPo until its full. My load is a micro controller system, so theres no concern that the USB cant handle the total load

2. There is only a single LiPo battery.

I figured out that I can use ideal diodes such as the LM66200 to handle the switching, since the USB's 5V should always be greater than the battery voltage. My concern is, after the ideal diode, do I need an LDO or a switcher?

The estimated total load is set at 1A, plus charging current. An LDO makes sense for the battery, since it wont be much higher than the required 3.3V, but the higher 5V USB voltage, at that current, concerns me.

Thoughts? Sorry if this does not make sense, I am trying my best

Hopefully I’m not in the wrong place for this, just not sure where to get some help on this problem. I’m pursuing a degree in EE technology and in the AC circuits course learning Nodal analysis. I’m actually very familiar with most of this course already as I taught the material while in the Navy, but nodal analysis is new. I don’t find it difficult but I cannot for the life of me figure this one out, hopefully one of y’all can lend a hand, and thanks in advance. This circuit gave me resistance/reactance for all but C1, and I’m solving for voltage from c-b. I know how to write out my equations, but without Xc1 I don’t understand how I can solve for vc-b.

with a breadboard, jumper wires, ATOMS3 LITE ESP32S3 DEV KIT, etc, can I make a wifi controlled button to turn on my computer with the 2 power pins on the mobo? controller of choice is Home Assistant so I can use something like ESPHome. also how would I power it?

I do turn off my psu from the switch at night and then turn it on in the morning.

I would also like to keep normal functions, so could I add another power button to the breadboard somewhere so I have a physical switch? e.g. if I am away and forget to turn on my PC, I can do so with HA and then remote desktop in. Still, if I was at my desk, I could click a button (either on the breadboard or just a normal power button connected to the breadboard) to turn it on. (that would be preferred so I can get a keyboard-like button from Temu)

It would just be a normal 1 press human click needed. no matter if the PC is on or not since I can use it to power off my pc.

Also for power cuts when I'm not here, I would like it so that when it gets plugged in, it instantly turns on again. A battery for it would be nice, however, I will save money to not get one since I can plug it into my UPS (which my PC is plugged into).

I am kinda a noob, so when giving instructions tell me the full names of things, instead of controller, relay, etc. (e.g. dont say "controller" say "ESP___").

I am in NZ so Digikey and Jaycar are good sellers. If you know any other good ones then that would be great :D

EDIT: I completely forgot about Wake On LAN

One pin has fallen out of our Shopify iPad mount, disabling the charging function. Would much rather fix it than buy the $160 replacement. How can I identify the specs of the pin so that I can order the correct replacement part? Haven’t been able to find the part by searching for info on the mount, unfortunately.

I found a bag with my old electronics class soldering kits from school, and one of them is the "Chaney Super LED Chaser Kit." I'm working on a small case to hold the kit just as a fun side project, but I'm stuck trying to figure out the sizing for the case until I work out what type of battery to use. Normally, it operates with a regular 9V battery. I have a scavenged 16350 battery (with USB-C charging circuitry attached) and I'd like to use that if possible due to the relatively small size. As best I can tell with some quick testing, my rechargeable battery is able to power the kit with no issue.

Is there a safe way I can add this rechargeable battery to my kit, or would it just be better to stick with a plain 9V? What would be the best way to add it, if it's possible?

The connector for the audio jack from the DENON DA-10 came loose (the plastic broke down somehow). I don’t see anything else immediately wrong with it, so I wanted to try just replacing the connector between the audio jack and the main board.

But I don’t know what to look for. I need to replace the male(?) connector. The krimped cables look fine to me, no need to replace those… I think.

Imgur album; https://imgur.com/a/R1j2EEK

In the pictures you can see the connector I need. It was the same on both ends of the cable. It was used to connect the board with the audio jack (pictured) to the main board, so it's just an extension.

The closest I have been able to find is this one: https://www.ivent.co.nz/product/8-pin-smd-1mm-male-ra-shrouded-header/38995

Being being based in europe though I'd rather avoid ordering there when I'm not even sure this will fit. The DA-10 is also not being sold by DENON anymore so I doubt they will be able to help if I asked them.

pitch is about 1.25.

I have a 12V relay (PR8-12V-450-1A) that has a coil resistance of 320Ω. The 12V is being supplied by an AC/DC converter (IRM-01-12S) that is rated for 83mA of current. I would like to know whether the relay will maintain 320Ω indefinitely when the voltage is applied to the coil, or if the listed coil resistance is referring to the impedance of the coil itself, which will decrease as the circuit approaches steady state (due to being an inductor), therefore drawing too much current and damaging my AC/DC converter.

In computers there often seem to be multiple high Q quartz crystals as expensive discrete components to create different frequencies, but have not seen a lot of LC tanks. Resistors are bad for Q . So really, a highQ , low phase noise PLL needs variable L or C. Microelectronics was fast since the 70s. So a varactor really is just a discrete diode . Those seem to have a doping profile along z. Contacts on top and bottom. Totally different from integrated circuits. A small, cheap Crystal. So a VCO needs 3 discrete parts and 3 pins : two diodes and one coil. So this is more expensive? My SVGA graphics card needed 3 crystals for different graphics modes although the ISA bus offers a clock! Computers with TV out cannot switch between PAL and NTSC .

My Roomba started only going backwards one day, after multiple tests and searches my conclusion is that it's one of the sensors, I have looked up how to diagnose ir emitters and receivers, but I don't know what this sensor is or how to measure it? Any help?

It works fine when I power it on for about 2-3 minutes, then it’s silent for a minute or two then back on for a few seconds then silent until I shut it off and turn it back on. Does anyone have an idea why? I’d rlly like to fix it if possible. It’s connected to my TV through an optical cord and at first I thought it was the cord but it does the same thing in Bluetooth mode as well. It never powers off just goes silent. When speakers are working they sound fine.

I have the circled part getting very hot and causing the board to fail. It seems like a VReg based on the voltage marking beside it, and the 8 pins, but it looks like a capacitor. The C106 and C107 beside it are 0805