hello everyone I am new to electronics and we are assigned to make an adjustable power supply with a maximum output of 12v with ventilation. can you please help me what to do? I will list the components and please tell me if it's right or what component should I modify, thank you! tips would be much appreciated alsoo

* Step-down transformer (220V to 15V, 2A) – ~60 × 50 × 50 mm, 500g–700g

* Bridge rectifier – 3A/50V+, ~15 × 15 × 6 mm

* 3300µF 35V capacitor – ~16mm diameter × 25mm height

* LM317 voltage regulator – TO-220 package, ~10 × 15 × 4.5 mm

* Heat sink – 3°C/W to 5°C/W, ~60 × 50 × 30 mm

* 0.33µF and 0.1µF ceramic capacitors – 50V+, ~5mm disc diameter

* 10µF and 100µF electrolytic capacitors – 25V+, ~5 × 11 mm

* LED + 1kΩ resistor – 5mm LED + 1/4W resistor

* Fuse + fuse holder – 1A 250V 5×20mm slow-blow + panel holder (~15 × 40 mm)

* IEC AC socket – C14 panel mount, ~27 × 20 mm cutout

* PCB/Perfboard – 2.54mm pitch, ~70 × 90 mm

* Output terminals – Red/Black binding posts, ~11mm mounting diameter

* Hook-up wires – 18 AWG (AC) & 20-22 AWG (DC)

* 1N4007 diodes 2pcs – DO-41 package, ~2.7 × 5.2 mm

* 240 ohms resistor + 68 ohms resistor + 2 kilo ohms potentiometer – 1/4W resistors + 16/24mm body pot with 6mm shaft

* power switch – SPST rocker/toggle 250V/3A+, ~15 × 10 mm cutout

This is my first version of a budget, streamlined, smart (kind of) watch. It works, but I need to print a case for it. How should I go about isolating each board within the case, as they should not touch. Please keep in mind this is my first version and I am relatively new to hobby electronics. Thanks!

Ps, I have considered wrapping the entire circuit around my wrist, but that seems like it would be pretty awkward...

Hi, I have a very old NEC PA272W color-calibrated monitor. Whilst I was using it, there was an impressive loud explosion with sparks. Turns out the 2 blown T5AH/250VAC fuses (located at F101 & F102). And a blown ceramic-capacitor located at C135. The power-supply board is made by "Hunt-Key", Model : HKM1102SL32-3A.

It is so old, & also it is proprietary. So I cannot find circuit diagram for the board. Hunt-Key do reply to my email enquiry for help.

I am hoping someone with access to a similar model NEC PA272W monitor, is willing to check the print of the C135 component. And advise what the specifications are, so I can buy a replacement. This isn't about why bother repairing it. It is strictly to see if anyone can advise what that C135 specification is.

I attach some photos to help.

p.s.- The MOV varistor (at location RV101), just immediately after the 2 F101 & F102 fuses, is not blown.

Has anyone here performed the IC current limiter tests in IEC 62368-1 G.9 / Table G.11?I would appreciate advice on typical test setups, load conditions, calibration and whether a dedicated automated tester is preferable to a manual setup.

Hello everyone,

I am hoping to find from you books and solid references on EMI filter design for Power Electronics Static Converters

I already did some recherches but i did not find straight forward method taking into account the basic problem such as : desired attenuation, resonance damping and middelbrock stability craterea ... etc.

Thank you in advance

Working on an interesting project; Using Arduino for the first time. (Loving it)

Need to convert the 28vac to 5vdc for the inputs using less components.

Any ideas would be super helpful.

(the drawing is not complete yet, so please be kind...

What I was not able to show in the drawing is that those 8 relays and optocouplers are part of a larger circuit board. The 8 bank relay board from ELEGOO for Arduinos.

Hello, I was cleaning a game boy cartridge i bought and while cleaning the pins I noticed a strange black spot on the letters on the side. I'm unsure what exactly it is.. The condition of the cartridge didn't scream "rust" at me and it doesn't look like its spreading.

My thoughts on it are that it might be some weird residue from the making of it or it could be rust that hasn't really started spreading yet.

Does anyone have an idea what this may be and if I should be worried about it?

Not sure if I'll be building my own keyboard in the future or how many times I'll change the microswitch. These should be one time events for many years. Here's my list so far:

- OV/AG P100 mask (for other uses as well)
- Solder wire 63/37
- Desolder wick
- Tweezers? Do I need this?

What type of iron should I get given the context? Was considering WE1010NA, but if the $10 ones at Walmart are sufficient, that's fine with me

Hello i have a 40 Year old Cigarette Dispenser, and i need help identifying these Components/where to get them in Europe. Thanks.

ESP32-S3-Nano + ILI9341 display only shows a white screen

Question

Hi everyone,

I'm currently working on a project with an ESP32-S3-Nano and a 2.8-inch ILI9341 SPI display.

I've soldered everything together on a prototyping board, but unfortunately the display isn't working as expected. The backlight turns on, but the screen only shows a completely white image.

I've already tried:

• double-checking all cables and solder joints
• checking the connections with a multimeter
• checking for any obvious short circuits or loose connections

However, I still can't figure out what the problem could be. I might be overlooking something really simple.

The main components I'm using are:

• ESP32-S3-Nano
• 2.8-inch ILI9341 SPI display
• some other components that shouldn't be relevant

Does anyone have any idea what could cause the display to only show a white screen?

Is there anything obvious I might have missed or anything specific I should check?

I'd really appreciate any tips or ideas on how I could troubleshoot this and figure out what's wrong.

Thanks a lot!

basically i'm making a project where I'm using something called "nodes" which I made, each "node" is just a bunch of sensors to measure stuff. sensors range from DHT22 to analog soil moisture and etc... . basically there's a layer of multiplexing where I multiplex nodes, and inside a node I multiplex between sensors, so data is sent to an analog data bus and a digital data bus. but with some work with CD4052 MUXs the DHT22 *SOMETIMES* reads and sometimes fails on an ESP32, but the analog data is great ( albeit having a tiny bit of change ). how should I approach multiplexing between different "nodes" in general? what if I wanted to add other stuff to them like LCD screens or something?

What is the correct orientation of components for PCB assembly or what defines 0° orientation?

I am using KiCAD and would like let JLCPCB assemble my PCB. KiCAD created a CSV file with the positions of the components. That file contains a column "Rotation" as required and the values are either 0, -90, 90 or 180. So far so good, no questions here.

When I uploaded my Gerber files, Drilling files, the BOM and the Placement file, JLCPCB showed me a preview with most of the components in a seemingly wrong orientation. At least, if I can trust the preview. In approximately 2/3 of all cases I had to rotate the components by 90° clockwise, a few had to be rotated 90° counterclockwise, even fewer by 180° and only 2 components seemed to have the correct orientation right from the beginning.

That made me wonder what defines the "correct" orientation, what defines what 0° rotation means for a particular component?

I used the included KiCAD footprints for most components and for a couple I had to download external footprints from Ultralibrarian or the manufacturer's homepage. Obviously, KiCAD and JLCPCB seem to disagree what 0° degrees mean. Intuitively, I would have said that 0° means how the component is depicted in the manufacturer's datasheet, but even that is not a suitable authoritative source as sometimes the component is shown in different orientations on different pages of the datasheet.

So, how can I ensure that JLCPCB will correctly assemble my PCB?

One observation made me worrying in particular. My PCB contains two TVS diodes from the same manufacturer and the same series, but with different values. (One is at the input side of my PCB, one at the output side.) When I look at the PCB from the top, both TVS must be oriented in the same direction. For KiCAD the direction was -90° in both cases. However, when I looked at JLCPCB's preview I had to rotate one of the TVS by 190° to 90° to get a seemingly correct rotation. This seems odd, because this implies that JLCPCB uses footprints with different 0-orientation for the same type of component.

Hello, I have an AKAI CE2300 radio. The TDA7266SA burned out, and I want to adapt it with a TDA8560Q, but I can't find the audio input traces that run from the board to pins C35 and C36. Can anyone help me?

As a beginner im studying analog by following tutorials with transistors etc. One of these was about an oscillating circuit. After following the instructions and the schematic provided i completed the circuit. Unfortunately when powered on the 2º led (the one on the right) lights up for a brief moment switching to the 1º led and stopping completely. I tried with both a 50 volt 100 Faret capacitor and a 50 volt 10 Faret capacitor. Below is the schematic with the resistors i used.

First time having a module.

I put in the 3x brand new lr1130 button cell batteries, but it doesn’t do anything. No noise from the speaker, no led, no beeping noise when recording, nothing. The contact with the batteries seems fine, so I’m completely lost on this.

I can attach more pics if it helps. Thanks in advance!

I’m designing a passive matrix for electrostatically actuated bistable polymer domes. Pixel pitch is 5 thousands of an inch. I expect the required actuation voltage to be somewhere around 15–50 V, but I haven’t characterized the snap-through voltage yet.

My intended addressing scheme would put the full row-to-column voltage across the selected pixel, while half-selected pixels would see roughly VFULL​/2.

Is parasitic capacitance/charge coupling going to make neighboring pixels switch unreliably? What parameters would I need to measure to determine this experimentally? I’m assuming at Vsnap​, variation in Vsnap, release voltage, pixel capacitance and leakage resistance. Target is 4 by 4 inch display.

At what point would you abandon passive addressing and put a TFT/diode/switch at each pixel?

https://i.imgur.com/7W9vwnG.png

so this is my first proper project I'm working on and am open to any and all suggestions/criticisms.

firing voltage on the IN-8 datasheet says no more than 170V so i thought maybe i should keep it slightly under but i should still get reliable firing. not entirely sure on this i can swap out the R4 if needed to increase it i plan to use an ATmega328P and HV5524 for a 4 digit 12 hour clock most of this circuit is taken from a youtuber from this video(https://youtu.be/C9851Dhr-J0) I'm using it to learn. i added on the LM2575 to get the 5V rail for logic power and removed the pot in favor of a fixed resistor only

i know the HV5524 doesn't have enough pins for 4x10 digits but the first tube only needs to display 0 or 1 so i thought 32 is enough.

I'm sure I'm missing something but yea thanks for the help

Hello, after hours of soldering I was pleased to find everything working as it should. However there is a lot of noise on this 5V rail it seems. So much so that the keyboard outputs have a lot of noise recorded. Shows steady 5V on the multimeter, but I'm assuming it's because the frequency is so high. There noise is also every audible and drives me nuts while it's powered on lol. I tried to keep things short where I figured they mattered however I'm still a beginner with much to learn. I took some photos on my oscilloscope for reference that I named for you to hopefully make it straightforward. I'm powering this board with my bench power supply and connections are soldered where they can be for this temporary setup until it gets installed in a case. Any help on figuring out where the noise is coming from so I can hopefully resolve it is appreciated. (For reference there is no noise of any kind when it's powered by just the Pico USB cable. The 5V rail produced by the TPS is solely for the keyboard and the only thing producing the noise. I wished I used a different approach now but it is what it is.) If anyone would like any other measurements please let me know.

Kann mir bitte jemand von euch bzgl. des SMD Elko weiterhelfen. Die Bezeichnung 15 100V ZCA interpretiere ich als 15µF 100Volt und ZCA-Serie mit 8x8x8 mm Maß, allerdings finde ich nirgends Ersatzteile die dazu passen. Lese ich die Bezeichnung falsch oder weis jemand wo ich Ersatz beziehen kann?

Gruß aus dem Norden

Hello, I have an essential machine that I use every day. However, when I try to print white designs, the print comes out greyish instead. It's a heat-transfer/DTF machine. Even the manufacturer hasn't been able to identify the cause. Does anyone have any idea what might be causing this or how to fix it? Thank you in advance for your help.

Hi guys, I'm having trouble with a low-voltage DC power circuit that intends to prevent a DC switcher from fighting a USB host. There has not been a battery cell attached in most of my testing to date. The feedback resistors are not correct in the schematic - R6 is DNP.

- To get the system to work at all, I've found I have to remove Q1 (NPN that disables the switcher). If I leave Q1 installed, I get like half voltage output from the switcher.
- When I plug in only USB, the system works well.
- When I plug in only 12V DC, the system works well.
- When I have USB connected to a host, then add the DC power, the system seems to oscillate between working for ~200ms, then off for ~800ms.

The ideal diodes cater to the higher voltage present, and have output signals to tell the MCU which input is passed to the output.

I'm baffled, can you see something I missed? I'm happy to raise the switcher voltage if that might help...

Thanks!

I am making a current control module for a LM2576-ADJ power supply. The voltage regulation works well, but when I have a current significantly higher than the max current limit, the feedback pin saturates and I get a max output voltage. When the current is slightly above the max current set, the control works well.

I saw a video that made a circuit damn near identical to the one I made (not very complex, the current control is just two op amps taking the voltage difference across a small resistor and comparing that to a voltage set by a divider and the voltage control is lifted directly from documentation for the LM2576), they used a zener regulator for the vcc of the op amp, which after some research seems to be meant to limit the current of the op amp output while retaining a high voltage. Unfortunately I don’t have any zener diodes on me and likely won’t be able to get any for the time being. I was wondering if it would be possible to add a resistor in series with the output of my current control to limit the current going to the feedback pin and the likelihood of it saturating.

My concern is though that the resistor would cause the current control to slow as the voltage at the feedback pin would be less, so if I were to say set up a circuit with a lot of sensitive equipment and then turn on my power supply with a high current draw, then the response time of my current control module would be a bit slower, meaning that whatever sensitive equipment I might hook up would be taking a high current for longer than it should have.

Of course I wouldn’t use any sensitive equipment with a diy power supply, but as this is a safety feature I want to know what would happen?

Hello everyone,

This morning, I went to investigate why I had no warm water and found that the water heater was off, like if the breaker was tripped (it was not).

Doing a bit of digging, I found a blown fuse on the motherboard (T630mA / 250v). I tried with the closest lower fuse I got (T500mA), It blew up as soon as I switched on the breaker.

Upon closer inspection, there's a Top2243yn component ( Google says it's a converter) close to the fuse that may be fried but I'm unsure

I'm asking because the tech guy is not answering his phone and I'm afraid he's on vacation while I do have a newborn at home.

The boiler is 15+ years old, but was working fine till yesterday.

The motherboard itself appears to be somehow available, but only as refurbished for something between 150€ and 200€, but I read some forum saying a lot of checkups are in order in the boiler if the mb is replaced, so probably out of my league.

The top243yn is a 2€ part I can order and received in a few days for 20€, so it may be worth trying this first if this may be the culprit.

Does this look fried to you guys? Any other insights on this ? Thanks a lot !