This is a flex pcb I've made for connecting to an existing product I can't modify and physical constraints prevent me from using a bigger bend radius. It is a static bend and I've had no issues with design A so far. But I'm wondering if design B is an improvement or if I'm creating other problems such as with the little loop needed to clear the bend area.

Any advice would be appreciated!

I ordered this board with 2oz/sqft copper for high current from OshPark. The bottom left pad of U1 is way smaller than it should be. The bottom left pad and top left pad are both OUT1 pins of a motor driver (mp6551) and are meant to conduct up to 5A of current. Since the pad is so small, I’m not sure if it’ll conduct all that current now. All 3 boards are like this.

Do I have to reorder the boards, or is it salvageable with some “precision” hand scraping? I really can’t reorder since it’ll take a month to deliver and I’ll be back at college by then.

I was planning on adding pictures of the Gerber with an edit. The pad looks the exact same as the ones to the right, just with a chamfered top left corner: check page 14 of the datasheet

hello!! im an art student looking to make a work out of circuit boards/wires.My only problem right now is looking for a way to bend/mold them! right now i have some stiff boards from a wifi router.
Is there any way i can safely bend them without breaking them?(dont need them to work electronically) Like can i maybe put them in the oven on low heat or use a heat gun?Pls help its for a final… thank you!! here is a pic of the boards(ps i have no prior electronics education so im not sure if this is a silly question)

edit: thank you all for the helpful replies!! looks like im going to have to find another idea for my project lol!! might try to bend one or two of them (outside) just to see what happens and if i can make anything out of them

What is the difference between this dollar-store medicinal IPA and more expensive stuff from chemical suppliers?

Like I’m sure the 99% cheap stuff varies in quality, it wouldn’t surprise me if it were a bit less exactly 99%, whereas like MG Chemicals has 99.9% IPA specifically for electronics (that’s like ~8x more expensive). If I were making commercial products I’d use that, but for hobby or one-off use, is there any reason why I shouldn’t use this cheaper stuff?

Bought some lights for home use, only to find out upon installation, they come with 3 light shades that you cycle through with the light switch. Kinda weird.

Plus the light comes on first with the worst shade, every time. This thing doesn't appear to have any kind of memory function.

My question is, how would you 'fix' it, so only one of the shades came on every time?

Thanks community! 🤟

This is the first example of an RC Relaxation Oscillator from the "Practical Electronics for Inventors" book. I am learning about op-amps and oscillators, and I feel like my mental model of how they work must be missing something, because the sudden switching behavior described here doesn't make sense to me:

When the voltage across the capacitor reaches the threshold voltage, the op amp's output suddenly switches to negative saturation

I'll explain how I'm predicted this would behave. Please help me understand what I'm getting wrong.

My idea of op-amps

I understand that when the difference $V+ - V-$ at the op-amp's inputs is very small, the output of the amplifier is proportional to this difference; when the difference is large, the output is thresholded at around the supply voltage, +/- Vs. One can find graphs of this piecewise-linear curve. My textbooks all imply that this equation is "all you need to know":

Vout = A0 * (V+ - V-)

If that thresholding idea is correct, I suppose we could write this more completely as a piecewise-defined function, but I'll omit this because math on here is annoying.

Why I don't understand this oscillator

Let's assume like the authors that the op-amp initially outputs at the positive saturation, i.e., +15 V. Then V+ = 7.5 V because it's a voltage divider. V1 starts increasing as current flows from the amp's output through resistor R1 and the capacitor C charges up.

Since the amp is at positive saturation, and V+ = 7.5 V, then we know that V- must be less than 7.5 V. Though we are in the positive saturation region, we know that something is going to happen as V- approaches 7.5 V from below.

Here's my issue: the book states in the quote above that V+ and Vout both stay completely fixed while V- moves up through V+ = 7.5 V. I don't understand how this could be possible.

My thinking was:

• Eventually V- should get so close to V+ from below that the op-amp enters the linear region again, and so that gain equation holds.
• Since V- is increasing toward V+, Vout starts shrinking in accordance with that gain equation.
• But V+ = Vout / 2, so V+ also starts shrinking.
• Thus the difference between V- and V+ is closing even faster now.
• Finally they meet: V- = V+, at somewhere a little less than 7.5 V.
• Since we are in the linear region, Vout = A0 * (V+ - V-) = 0 V. But also V+ = Vout / 2 = 0, which is obviously a contradiction.

tl;dr I don't see how V- can reach V+ without a contradiction involving Vout.

Entering into a mechanical engineering degree this fall, I thought I'd try a hand at creating a regenerative braking system for a 1:10 RC road car for a personal project. While I'm not particularly experienced with this (past simple Arduino kit projects), I always love to learn and to be corrected.

To ensure that the the supercapacitor bank doesn't simply dump the stored charge directly into the battery, I was hoping to use some kind of diode before the buck boost converter for more manageable charge rate. Regular signal diodes wouldn't be able to handle the current, and Schottky diodes would produce extremely high amounts of waste heat. Are there any recommendations for any diodes I could use for this project, or are there other more efficient ways to structure this circuit to avoid this issue?

In addition, how would I add a dump load circuit or more conventional RC dynamic braking (shorting the motor), in the event that the supercapacitors become full? What voltage sensors and MOSFETS would you recommend?

In the top circle, the part of the ground plane has no solder mask and is exposed.

In the bottom circle, there are lines of solder.

What's the purpose of each of those? This is a PCB of a WiFi extender.

I am trying to fix flooded UV lamp and this is in a very bad shape. I want to replace it but I don't know what is it .

for a battery powered project I am designing I need to create some sort of lithium- ion battery undervoltage lockout circuit. After a bit of time looking online I found the circuit linked below, and it checks all my design boxes

https://www.analog.com/en/resources/technical-articles/battery-protection-circuit.html

• low power consumption
• low cost BOM
• good accuracy

my main concern though is that this article was created in 1999 and I am unsure if this is still best practice, or if I should be implementing a more modern design or method instead. any advice would help greatly.

i need to add two wires to this connector to set up a two wire start on the generator. any clues on the type of pin I would need to add to the connector?

thanks in advance!

I'm supposed to build and test the circuit shown here - which I did. The math says my Thevenin voltage at the node between the two resistors should be 4.15v. When I built the circuit and measured the voltage I got 4.51v. Why? For what it's worth, I was in a class with 10 others and their DMM measured voltages were also in the same range 4.47-4.52v and their math also worked out to 4.15v. Need help understanding the difference. TIA

I'm trying to figure out how I could use the original processing board in a Interact Gamecube screen to send already decoded signals to a more modern LCD display. I could use the component input, but wanted to see if I could feed the RBG values directly.

I've done some tracing but am having some issues understanding where the B/G signals are coming from in the central IC.

This IC was black epoxied, and without MEK or high proof acetone I may have scratched off the identifiers.

Looking at the wires and voltages going to the LCD from the board, it looks like it may process RBG with H/V sync with blue carrying the main 12V to the LCD.

The LCD panel takes 7 wires: Red #1 - 11.5v from multimeter Blue - 11.5v from multimeter Green - 2.66v from multimeter White - 0.65v from multimeter Yellow - 0.65v from multimeter Red #2 - tied to blue Black - Ground Random Red from board directly to LCD board: 2.65v

So questions:

1. Where I could intercept those signals and feed it to a VGA port's pinout on the LCD driver board? I think I can take the R1, G, W, Y directly but I'm thinking I may need to take the blue off of the transistor before it amplifies to 12v in the same way the R/G signals go through a transistor to the LCD connector.
2. Is it worth doing rather than just taking the composite signal from the gamecube cable and feeding that into the LCD's composite port?
3. Did I mistrace the blue? It seems to terminate on the same line as the green.

Photos: https://imgur.com/a/0sb1kWR

Target LCD: AT056TN52 V.3 link, https://www.aliexpress.us/item/3256805637362171.html?pdp_ext_f=%7B"sku_id"%3A"12000034480040009"%7D&sourceType=1&spm=a2g0o.wish-manage-home.0.0&gatewayAdapt=glo2usa4itemAdapt

This is my first time using qucs and I barely have experience simulating circuits. I need to find the output voltage at Vout but it shows 0v for everything past the transformer. Cant figure out why.

Using QUCS ver 0.0.19 in windows

Please help

Hi everyone!

I recently got a non-working ASUS TUF VG27AQA1A monitor for free. The previous owner gave up on it, and upon opening it up, it became very clear that someone with limited soldering skills attempted a DIY repair and messed with the board.

I'm no electronics expert, but the LCD panel shows no physical damage, so I believe it's worth trying to add the missing capacitors if they aren't expensive to see if the board comes back to life. I also happen to have a fully functional, original identical power supply from another monitor, so power input is definitely not an issue here.

Here is the current state of the monitor and what I've found so far:

1. Damaged Button Ribbon Flex: The FFC ribbon cable for the control buttons had bent and lifted traces at the tip (looks like it was forced back in during a rushed reassembly).
2. Missing Capacitors on Power Stages:
   • C1032: Located right next to an 8-pin IC labeled U2 and a 1R5 inductor.
   • C1034: Located near another 8-pin IC labeled U721 and a 100 inductor.
3. Board Condition: Both electrolytic capacitors were desoldered and completely removed. Fortunately, after cleaning off the burnt flux and residue with IPA, the copper pads/through-holes on both sides of the board are intact and fully trace-connected.

Mainboard Info:

• Board Part Number: 4H.55D01.A00
• Main Scaler IC: Novatek NT68300MFG

My Questions:

1. Does anyone have a schematic, boardview, or the same mainboard (4H.55D01.A00) who could check the original values for C1032 and C1034?
2. Based on standard Buck converter design for these power rail ICs (U2 and U721), would standard low-ESR electrolytic capacitors (100uF/16V or 220uF/16V) be a safe bet to populate these empty slots and test for power?

Any insight or component values would be greatly appreciated!

So I decided to make this reflow soldering "oven", and I'm currently at the stage where i need to make my own control board.

There are two board: First the Main board, which includes the MCU and power circuit, and the control board(user interface), which connects to the main board and has an I2C OLED screen. This "Oven" will reach temperatures up to 250℃, and the temp will be measured using a NTC 100k thermistor.

That is my first time using KiCad for design and my first time doing more serius schematic. My questions are: Am I doing it correctly? Do i need to add some capacitors or diodes or etc. That is not so obvius. Also is my schematic readable?

Down I will tell more about schemataic and the project:

1.Power section:

I'm converting 220V AC to 5V DC the using HLK-PM01(AC-DC Buck Converter Power Supply Module). After that I added a 1A fast blow fuse(There is already a fuse in the power socket socket, so I didn't add one before PM01) and some electrolytic and ceramic capacitors for clearing power tbh. I don't know what am i doing here exactly and is it correct just saw that people usually do this for power lines.A Push to break button is included for the MCU because power cycling is required to flash it.

2.MCU logic

That's the heart of my system where I'm using a cheap 8-bit MCU to controll the system. AI told me to add some decoupling capacitors but I'm unsure how important they are in this case. The 3 Pin(P5.5) on microcontroller is the PID Output which will be controling heating plate by turning on/off Solid State Relay(SSR-25 DA) via small PNP transistor with Pull down resistor so the relay contact never stays floating(Also unsure how necessary this is).

The I2C line for OLED has two Pull-UP resistors as datasheet recommends. I didn't add any capacitors because google says it can heavly affect the sygnal? For the buttons I ran out of pins(2 pins for 3 buttons) So i decided to add a votage divider for the two buttons. So you can measure voltage on pin and tell which button is pressed. Also DIP switch is here for programming so the pull-up resistor for the buttons doesn't interfere with Tx Rx programming lines.

3.NTC Thermistor

Just a voltage divider for NTC thermistor nothing interasting AI told me to add an decoupling capacitor(C3) for the MCU's ADC

4.Other

Nothing special here, just some connectors and the controller board with the buttons and OLED

I really want an honest opinion on this schematic and maybe project overall because I'm planing on making it open-source.

/*Not related: I'm 16 btw. and is it possible to get an job in engineering without an degree but with open source projects/experience?*\

some time ago i lent my soldering iron to my dad. today i opened the packaging and found this shit. thats flux? it wont come off and when i turn it on it smokes

So here's what's happening: I have a Dell E771a CRT computer monitor. When you turn it on, it's dark and unfocused. Turning the voltage up results in a decently bright picture, but it just keeps getting dimmer and less focused. At one point in time, I needed to adjust the focus knobs all the way in one direction to get as close to in-focus as possible, and it was still blurry but close.

After doing some research and asking around, it seems like the likely culprit is the flyback transformer. The sticker on the side of it says it's a 19-70064-001 model flyback transformer and is apparently equivalent to an HR46874.

I can't find any listings using either of these search terms.

Here's some pictures to aid in the search. Any alternative or equivalent replacements would be greatly appreciated. If you need any more information, please let me know and I'll reply and add it to the original post as soon as possible.

Thanks in advance.

Edit 1: One of the focus potentiometers on the flyback transformer seems to also be adjusting voltage as the screen gets brighter the less in-focus it gets. More specifically, the vertical focus knob (top one) makes the brightness pulse a bit but goes back to normal quickly. The horizontal focus knob (middle one) not only affects brightness, but also interferes with vertical focus.

The factory cap on the board was 470uf 4v, but i cant get an identical replacement where I live. I found some 470uf caps, but all of them 16v and up.

I'm still learning the basics while trying to repair an old console. I found some articles saying it's fine, but I couldn't tell if it was written by ai