/r/AskElectronics

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A subreddit for practical questions about component-level electronic circuits: design, repair, component buying, test gear and tools.

A subreddit for practical questions about component-level electronic circuits: design, repair, component buying, test gear and tools.

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/r/AskElectronics

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1

Electronic Design for an EEE

I'm an Electrical & Electronics Engineer who graduated a year ago and currently doing master's on physics but I would like to also improve my self on Electronic Circuit design. As per my field I know the components how they behave and how to do calculations on them and every now and then even if I can't remember the exact formulas I know where to look to. Even during my Bachelor's I wanted to get more involved in circuit design but it wasn't on the syllabus to actually design any circuit but just to calculate certain resistances gains or etc. I would like to ask you what path shall I follow?

We used to use the electronic devices and circuit theory of Boylestad & Nashelsky for our Electronics course but this is more on the theoretical side. I want to perform in hand experiments and be able to design a circuit from the scratch upon the desire. I would like the book to teach me the process of design and give some example circuits which I may realize on my own. I have done some research and found books such as the Art of Electronics which seems to be somewhat compensating what I am looking for but I want to hear your suggestions as well. Due to my experience I don't want something too basic.

2 Comments
2024/03/26
00:45 UTC

1

Damaged components, part ID help requested

As the title states, I managed to damage 3 components while disassembling a vaporiser. Looks to be a transistor, a diode, and what i believe is a piezo speaker. Speaker Y1 and Diode D7 were basically junk and I couldn't get any direct part numbers from them... D13 was straight missing but it was indeed populated since the solder had a nice rectangular depression where the component was.

Based on a decent quality PCB photo from someone on the internet, I was able to determine that the D13 transistor should be a 2N7002 NPN MOSFET.

The Y1 speaker looks like: https://www.digikey.com/en/products/detail/ole-wolff-electronics-inc/OWMB-505020S-40-12D/16343856

The only item I am not sure about is the diode at D7. In the PCB photo, the only mark i see is "A" which, as you might imagine, isn't very useful. Any suggestions on how I can identify this part?

https://preview.redd.it/12yhmxalpkqc1.jpg?width=1280&format=pjpg&auto=webp&s=9c42912e38617472f2934e25f639f155907338a6

https://preview.redd.it/bzxsb2blpkqc1.jpg?width=1280&format=pjpg&auto=webp&s=ec2016d37bc1661a64d3f6ce9316ff58ccec1cca

https://preview.redd.it/lbxz01blpkqc1.jpg?width=3072&format=pjpg&auto=webp&s=b74009b7bcd23e60fafe6395f009bd52fbcabc63

0 Comments
2024/03/26
00:27 UTC

1

Input Bulk Capacitors for Power Input

Hello, I'm looking for some information on what capacitor values one should choose for bulk capacitance at a power input connector? I've seen some designs where people used a PI filter followed by a 10uF and 330uF capacitors. For example, the input power is 5V and it is supplying various switching regulators.

Thank you

0 Comments
2024/03/26
00:22 UTC

1

First time using 34063 and having trouble

This is my first time using the 34063. I followd this circuit almost exactly. By almost, i substituted the following values. also my input voltage is 12v but I don't think that is an issue is it(?)

Rsc - 1 ohm. R1 1k ohm R2 - 8.3k ohm. L - 100uH

My circuit is only drawing at most a few miliamps, this is supplying the negative rail to a filter op amp. Regardless of that, even with zero load I only get negative 7.8 volts, which i really struggle to understand. I tried to play with the values and i can get my voltage down lower but not up. I also played with rsc, when i went to 10 ohms for example my voltage went by half, even uploaded.

Maybe the IC is bad?

0 Comments
2024/03/26
00:17 UTC

1

Will these connectors work with wire soldered to them?

Hi, have got these switches for a guitar project but am now doubting whether or not the connectors will work with solder or if I’ll need to find some kind of converter? Any help is appreciated thank you!

5 Comments
2024/03/25
23:48 UTC

1

Mouser 3D Model Issue?

Hello, I made a new mouser account to download 3D models for parts but it doesn't let me download still. Does anyone have this issue? I called them and they said I'd have to purchase a part before my account is "verified" by the system...? Not sure why that is since I verified my account via email and all..

I need to download the model for this part : https://www.mouser.com/ProductDetail/MEMSIC/MMC5603NJ?qs=B6kkDfuK7%2FDOubZFFHvcXw%3D%3D and I don't know that I have another way of doing so, would anyone be able to help me with that?

1 Comment
2024/03/25
23:45 UTC

1

Connector on 3d Printer circuit board stuck closed...how to open?

Hello,

I need to switch out the circuit board on my 3d printer however the connector that the power cord fits into is stuck closed so I can't get the wire in. Obviously when I unscrew the screw it is supposed to pop open but it does not. Any ideas how to get it to open would be appreciated. In the pic it is the green connector, very top screw.

https://preview.redd.it/f8pmynu3gkqc1.png?width=224&format=png&auto=webp&s=84754880416ee0d89e9e05a377bc8bff86a92a58

3 Comments
2024/03/25
23:37 UTC

1

What to do with broken port

Hello all, a micro usb port fell off this old speaker, I don’t really need it to look good as I have a new one but I want to practice my soldering skills on it.

I found this old female usb cable and I’m thinking of soldering it instead of the micro usb cable, where should I solder it?

1 Comment
2024/03/25
21:22 UTC

0

How can I finalize a PCB design?

Hello, I am summarizing my situation.

I am manufacturing a PCB with certain characteristics and size, I am working with a Dutch company in the development, unfortunately due to time factors and some errors made which have not been corrected and correcting it would take more time, fixing those errors made by them they want to add in modifications on my part among others, I have lost confidence in this company, so I find myself with a project already started, I do not have knowledge in the technical aspects of electronic systems, I find myself in the situation of not knowing if I am being scammed by the company that I have hired to simply get more money, since we have been in the same place for many months, I would like to know if all these changes and jobs are really adjusting to reality, since I have no knowledge of the subject.

The costs are much higher than what I had already agreed with them, which would not be a problem. Not knowing exactly if these costs are fully justified, I would like to know what possibility there is of finishing this project independently with another engineer, and then Go to a company with the design ready and tested, for production, with all the European requirements and standards for its Homologation.

Thanks!

1 Comment
2024/03/25
21:05 UTC

0

Fried 0-10v dimming LED drivers. Need help fixing themz

Is there any hope in replacing components? Anyone know which compenents would be fried? High voltage nuetral was hooked up to one of the dimming wire. Thanks

1 Comment
2024/03/25
21:06 UTC

2

Plug manufacturer

Any can tell the producer of this DC plug?

2 Comments
2024/03/25
21:01 UTC

2

Bench Power supply from factors...

So, long story short: I need a new bench PSU. One thing I've always disliked is that almost all bench PSUs I can find are thin, but deep. This is annoying for me, as I'd like to have my kit on a shallow shelf above the bench. The scope for example sits perfectly as it's wide but not too deep.

Is there such a thing as a bench PSU but in the form factor of a DSO? Or even a small "Display/connector" unit that sits on the bench/shelf with the power unit/tx in a separate box that could be mounted under said shelf?

There has to be something out there, surely I'm not the only one with this issue?

Very much welcome any suggestions - not looking to spend mega money though!

Cheers!!

4 Comments
2024/03/25
20:29 UTC

3

Do you know some other ways to build an AM radio?

Our group for a school project decided to build an AM radio. After sime research we found some seemingly "complex" circuits like the superheterodyne but also some schemes that seemed too easy to be true like this one. Do you think this one may work? (the chip is an OpAmp, not specified which model) Also can you point us to some other types of AM radios?

6 Comments
2024/03/25
20:33 UTC

1

PCB Layout review

Hello everyone,

I just finished two versions of PCB layout for a relay board, and I would like to ask for some feedback. I'm a beginner in this so any tips will be appreciated.

On the first one I'm using PCF8575 with 74HC14 logic inverter and ULN2003A. On the second pcb I'm using the MCP23017 directly with ULN2003A.

For the MCP23017 I also wanted to ask whether I need to add pull-down resistors for the output pins.

And my last question is about the LED's - I wanted to use blue led's but I only found them with 3-3.3Vf so there would be no room left for resistors and I have read that it's not good to connect them directly to 3.3V power source. So I found some red smd LED's on aliexpress with 2-2.2Vf, and in the description of the product they state that the forward current is 20mA. But I have read on several forums that 1mA is enough to light up these LED's so I used 470ohm resistors, which will be around 2mA. Is that correct?

PCF8575:

https://preview.redd.it/pic2sy6cdjqc1.png?width=2052&format=png&auto=webp&s=09e4e3229596c0270c8ea3f9a39115aadd1498e9

https://preview.redd.it/3ikj2vmadjqc1.png?width=1013&format=png&auto=webp&s=afb90b646f93463921cf5e027ba5a83341034ed5

https://preview.redd.it/twwcoumadjqc1.png?width=816&format=png&auto=webp&s=23df3885e950217246019dd68e97ffae7993666e

https://preview.redd.it/y8fravmadjqc1.png?width=902&format=png&auto=webp&s=63d3dfeb33e8ddbfb9352fece529c22c9e690fa2

MCP23017:

https://preview.redd.it/t9w7acpidjqc1.png?width=2052&format=png&auto=webp&s=423f2276a35b4719aa2fe0d47c02bf2d9d72bd39

https://preview.redd.it/ol2jmtchdjqc1.png?width=972&format=png&auto=webp&s=ae8b3ef84989a16bc6e8d2bbca511ef08250eee9

https://preview.redd.it/0bilhuchdjqc1.png?width=965&format=png&auto=webp&s=8b6c73095e62d78df084e6872a44e2bbd8646d97

https://preview.redd.it/m3c6k2dhdjqc1.png?width=1046&format=png&auto=webp&s=71b5f6392c35ce19d0a57c18f7ed7bc43eb64b72

0 Comments
2024/03/25
19:57 UTC

1

Trying to source a MOSFET component, but really confused by the values on sites like Digikey to find what will work.

Hello all, I'm beginner/hobbyist trying to learn some electronics so apologies for misusing terms. I have a project that sends ~3.3v PowerON signal, that I'm hoping to use a MOSFET to "switch on" a higher load application, and conversely, turn off when that PowerON signal goes away. I'm trying to search sites like DigiKey but I'm having difficulty parsing the filters/specs of various components. Here's a rough diagram of what I'm thinking:

https://preview.redd.it/wvdw6qsfijqc1.png?width=320&format=png&auto=webp&s=91e523b17261b10a26f89b7b4f6b92b7a672707b

I'm hoping there's a MOSFET that can sustain a 12v, 5.85A continuous load without burning up when it is "on", but I'm not even sure what to look for, or even if this is the correct/best approach. Any thoughts?

3 Comments
2024/03/25
20:30 UTC

1

Esp32 running wled as an on/off switch for a 5v fan?

I have a small ESP32 project using WLED to control ws2812b LEDs which needed a little airflow so I decided to add a 5v bushless dc fan running off the same power supply as the LEDs which starts on 24/7 so the fan ends up running all time. I want to make the fan turn on and off with the LEDs schedule made in WLED.

Afaik i can program a GPIO pin as the data line for a set of LEDs and use that 3.3v output with a transistor to control the 5v supply to the fan?

New with this stuff so any help would be great! TIA-a

2 Comments
2024/03/25
19:34 UTC

1

GND connected to VDD?

I am designing a circuit with STM32H743VI. This connection diagram is from datasheet of BNO055 sensor. This is my first time so I am pretty confused why this is drawn like the way it is. GNDIO also goes to VDDIO. Am I missing something here because the ground should not touch the power supply, right?

https://preview.redd.it/0vp2hlsjuiqc1.png?width=1052&format=png&auto=webp&s=7b6bff27e384bf20564c05352ae00375d1b056e0

https://cdn-shop.adafruit.com/datasheets/BST_BNO055_DS000_12.pdf

7 Comments
2024/03/25
18:15 UTC

0

Why does my waveform turns into a line after passing through the "not gate"? Also, Why the voltage changes from 5v to 1v and then, goes back to 5v passing the gate?

2 Comments
2024/03/25
18:32 UTC

1

Is there any libraries for digital logic, like the family 74HCxx available for the newest version of Ltspice?

1 Comment
2024/03/25
18:34 UTC

1

Can someone ELI5 on how to read caps? I'm trying to fully recap a CRT and have no idea how to properly identify a cap so I know which one to replace it with

I'm having 0 luck on understanding how to read and lookup the numbers on a cap. I've looked up multiple videos and can not grasp it. any help?

https://imgur.com/a/PLdajlq

6 Comments
2024/03/25
18:32 UTC

1

Transformer needs a snubber?

A few years ago, I replaced the CFL tube on a desk lamp with a few LED strips and a small SMPS. The lamp had a small ballast on the base for the CFL lamp, but it turns out the weight of it kept everything upright. So I decided to replace the light SMPS with a good old transformer+rectifier+bulk caps, and while it does run well, it seems that the transformer gives a horrible voltage spike when turning it on/off. My monitor is 30cm away, and sometimes shows lines or just goes black for a while. I was wondering what would be the best way to solve this? I was thinking a snubber network on the primary, or a varistor.

3 Comments
2024/03/25
18:07 UTC

1

Is a 0.22 ohm or 0.27 ohm fine for replacing a 0.24 ohm resistor?

So a resistor broke in the power supply for my samsung TV and im gonna replace it but i only have these two resistors available

Is it fine to be slightly higher or lower? and if so which one would be better?

Model number for the board:

PSLF790D04A BN44-00517A

5 Comments
2024/03/25
18:03 UTC

1

what is the use of the mosfets in this schematic?

I am trying to design circuit arounnd SSD1306 64*48 which is an oled display driver and I cant figure out the function of the mosfet part. I could not find this part in other people's schematics of different variant of the same driver

SSD1306 64*48 display driver

SSD1306 128*64 variant

Datasheet of SSD1306 64*48 : http://www.lcmlcd.com/PDF/SYO6448A00-3C135WN2-WCE.pdf

Adafruit Schematics for other variants of this driver : https://learn.adafruit.com/monochrome-oled-breakouts/downloads

4 Comments
2024/03/25
17:53 UTC

1

Help finding rugged panel mount USB pairs (dual male female).

Hello,

I'm building out a computer which will be enclosed in a relatively weatherproof box (pelican or similar) and I'd like to install a panel mounted USB port, which I can attach a camera to using a weatherproof USB coupling, similar to what you see a lot with 8-12 pin connectors (e.g. this one).

So far I'm having a lot of trouble finding USB connectors that come in pairs. I see a lot of connectors which are basically a female panel mount piece with a cap but no matching male cable piece. Does anyone know of a product like this?

I could of course go ahead and splice a USB cable to an M12 or similar like the one I linked, but I'm trying to avoid doing this for this project.

Thank you.

1 Comment
2024/03/25
16:40 UTC

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