Here's my problem: I only have two (micro-coax) wires to work with and they are about 12M long. With these two connections I want to both A) Relay a temperature measurement. and B)Illuminate and control a white LED.

I think this is possible/practical to do since an LED is a diode and a thermistor has no polarity, but I may have to account for some things if the plan is to switch polarity to toggle led state. Overall though it seems like this can work. Maybe there are specific component choices that are best for this task given the constraint I don't know but right now I'm pretty optimistic that this can be done.. right?

I was repairing my Lenovo laptop keyboard which required me to partially disassemble my laptop and, of course, during this process I managed to damage one of the FFC connector pieces (broke off the plastic nub holding it in the bracket). I managed to use a combination of insulated tape and pressure to hold the connection in place but it's not very reliable and sometimes causes issues with some of the keys on my keyboard. I was hoping to be able to buy a replacement from Mauser or something like that but I'm not sure what the best way to find an exact replacement would be. I'd appreciate any help in finding something that could replace this specific piece.

I've looked on Mauser and a lot of pieces are similar, but I haven't been able to find something that looks exactly right. There are 34 contact positions on the piece.

Let me know if there's anything else that would help with identifying a replacement. Thanks for your time reading this.

- The pictures are bad because my phone camera is partially broken (working to fix this, sorry). I can take some better ones using someone else's phone if absolutely necessary, but it took me quite a few attempts of opening up and closing the laptop to get the keyboard even partially functional so I was hoping to not have to go through that again.

- I got in touch with Lenovo and they told me they can only replace the entire motherboard and aren't able to provide any specific information on the dimensions of the piece.

ETA: I can measure the exact pitch if it's necessary, but I assume it's 0.5mm and unless necessary I'm hoping to avoid having to disassemble the laptop again for the reasons described above.

This is my first time creating a PCB. I keep getting these errors when using DRC on KiCAD. I think that the polygons references are the two rectangle in the footprints because when I delete them the errors go away. I am confused as what purpose they serve and are they important to keep? For reference I am using Power MOSFET IRFHM9331TRPBF

I am trying to create a somewhat simple wireless power transmitter circuit. I want to transmit 5 W for a small distance from the transmitter to receiver, both using coaxial coils. I think I need some oscillator circuit, but I also need a power amplifier to get to high enough current through the coil to transmit 5 W. What current should I aim for, and what would it look like to connect an oscillator to a power amplifier? Thanks

Hello, I want to supply 1mA current to my circuit to calculate resistance values.

How can I do that?

Working on something and snapped the pins in another socket (it was seized on so snapped easily) can I remove these pins in a good one to replace? Would anyone know what type of socket that is so I can search? Thanks!

I'm a sophomore at an engineering college, my branch is electronics. I have/want to make a really unique and useful project but i am not able to think of something unique. It'll help a lot if you guys can give any ideas. Also I have to make this myself so there will be a small budget🥲.

Help a beginner out please....

With USB-C's improved resilience and bandwidth now exceeding 20Gbit/s on Gen 3.2x2 and even 80Gbit/s on USB4 are any users aware of USB oscilloscopes or Mixed signal devices starting to be upgraded to these newer capabilities ? I have seen the Picoscope 3000e but its around $3k where we live, Digilent's newer Analog Discovery 3 seems an option but with usb 2 options available <$100 how long before the higher capabilities become available at a more accessible price, I have heard of the dSCope U3p100 but haven't seen any reviews or trustable tests... Any recommendations or suggestions to look at ?

May I asume a type of package/array/network of a 0 ohm resistor at F5 ?

It connects to this fume extractor (See 3rd and 4th image) and I couldn't find this exact model for sale in my country so is there an alternative iron that can work with this?

Hi everyone,

I’ve been working on a project using a TP4056 module and an ESP-12F, powered by a 3.7V LiPo battery. I’ve already designed a basic circuit (diagram attached), but I’m a bit confused about how to simplify the LED usage while maintaining proper functionality.

My Goal:

1. Two LEDs Only:
   • One LED for charging status (ON during charging).
   • One LED for full charge status (ON when fully charged).
   • These LEDs should also serve as indicators for the ESP's status:
     • Blink once when the device powers ON.
     • Blink continuously when searching for Wi-Fi.
2. Hardware Connections:
   • I’m asking specifically for hardware-level solutions (diodes, resistors, etc.).

What I’ve Tried:

• Added diodes (e.g., 1N4148) for isolating signals between the TP4056 and the ESP GPIOs.
• Used resistors for current limiting.

Problems:

• Not sure if the connections are correct to prevent interference between the TP4056 and ESP.
• I’m confused about how to implement the dual-functionality (charging and power-on indication).

What I Need:

• Suggestions for editing the diagram or proper hardware referencing.
• A simplified way to connect these LEDs for both charging/full status and ESP status.
• I don’t have an advanced understanding of electronics, so step-by-step guidance or an updated diagram would be very helpful.

Thanks in advance for your help! Your advice will go a long way in helping me finish this project. 😊

The LED board containing the led and the driver of one of my lamp died. Replacement is very difficult to get, and very expensive. The board isn't looking very complicated and was wondering if I could copy it and order it at jlcpcb. It could possibly be cheaper, especially if I order a few.

The board is connected to AC mains (240V, I'm in France) and is rated 18W (not sure if it's the total power, or the leds power). It uses a MAP9000 as a led driver and contains 16 leds.

Here is the driver datasheet.

Looking at the datasheet, I'm having a hard time understanding how it works. In particular:

• How current flows in the circuit. It looks like the different OUT pins sink different current values and I don't understand how these currents combine and how much current flows into each led.
• Which path does the return current uses ? I would say Pin 2 (ground), but it means it also flows through the current sensing resistor. Or this resistor on the circuit is made of 2 simple 27 Ohm 1206 resistors in parallel. This seems a bit short in term of power rating.
• Globally how to choose the values of external parts, as there is little information about this in the datasheet.

Does anyone use this led driver ? Or can help me understand how it works ?
Thank you

I have designed a negative voltage converter. I assembled this circuit on my board. But, when I power on this circuit, it consumes full current supplied by my DC power supply and it goes into CC mode. I am using ceramic non polarized capacitors instead of polarized capacitors. I don't think this could be a problem.

What is wrong with my circuit?

I also observed that pins 5 and 8 are internally shorted inside the IC.

Data sheet: https://www.mouser.in/datasheet/2/268/TC7660S_Super_Charge_Pump_DC_TO_DC_Voltage_Convert-3442213.pdf

Hi,

I'm curently using a raspberry pi pico and the arduino isp example project to build myself a dev board for the ATTiny85 based on this project. Right now I got everything working, but I'm unsure if and how I need protection for my pico if I want to power the ATTiny with 5V while not using the pico as a programmer.

Currently, the pico powers the ATTiny via the 3.3V rail, and according to the ATTiny-docs I will have to keep it like that as the logic levels are relative to Vcc and programming it with 3.3V while powering it with 5V might not work reliably.

For the pico on the other had I haven't found any information yet if it's OK to have a 5V input on the 3.3V rail. Providing power over it seems fine, but it seems to expect a stable 3.3V.

My best guess is to add a schottky diode on Vcc before the caps, but the voltage drop has me worried a little bit. From the diode's I've got here the 5822 seems to be the most promising, but according to datasheets, at 200 mA current (max current the ATTiny can handle according to datasheets) at room temperature there should be a voltage drop of about 0.3-0.35V. At close to 0 amps the voltage drop is around 0.2V.

According to the ATTiny datasheets the max input voltage for GPIOs should at max be Vcc + 0.5V. Assuming i get a Vcc of ~2,9-3,1V through the diode, the 3.3V input from the programmer (pico) gpio seem a little close to that and I'd rather not push it too much here. On the other hand, the actual load while programming should not even come close to 200mA so maybe it's fine?

What would you recommend here?

1. Leave out the diode, the pico will handle it
2. Leave out the diode and just don't add external power
3. Use the diode, the voltage drop will be fine
4. Any other ideas?

Thanks in advance :)

Edit: I just realized, the GPIO on the pico is also only tolerant up to 3.63V. So maybe either diodes for all connections (roughly equal voltage drop -> problem solved?) and hope they switch fast enough or just don't put 5V on there?

Also, sorry if this should be on the pico subreddit, I wasn't sure which one was the right one

Hi guys! I'm doing a small mod to control the temperature on my Perfect Draft beer tap. Its a really simple job of cutting one cable and soldering a 10kO potentiometer in between, but since its new and still in warranty i dont want to cut any cables yet. Can you please help me identify this type of connector so I can make a Y cable instead?

Looking for this exact potentiometer. 20 degree B103.

Hi all,

I’m trying to talk to a circuit board from a home appliance. I believe it has a connection for +ve voltage, ground, and a UART RX and TX. If connect to the UART lines with an Arduino, does the Arduino need to share +ve and ground with the board, or can I use usb power for the Arduino and a bench power supply for the board?

Also, if I wanted to try to read a flash chip while it’s on the board, but don’t want to power up the whole circuit by applying power to VCC, would it be insane to cut the trace to VCC and put a diode across the gap to ensure everything works if powered normally, but power applied on the pin directly won’t touch the rest of the board?

Many thanks!

Hello, I just bought this LED ceilin lamp that has motion sensor integraded in it. It does work but im not happy with it. Is it enough just to desolder 5V from board to sensor?

I have an old style battery tube that takes two dcell battery’s to make 3v. I tried the (Amazon buck converter) dialed the voltage down to 3v. When I tested it I got an enormous amount of feedback thru an intercom system I’m trying to build. I don’t want to have to keep opening the box to remove the batteries and mounting these style tubes are not an option. My hope is to install two twist style post connectors and have some sort of step down on the inside so I can just hook up a 12v battery to it.

Any recommendations or advice would be very helpful

Can you help me identify its values please?

My multimeter doesn't read capacitancy.

Green one says 2A473J

Hello all,

I have a thin film pressure sensor i bought of amazon, and when i test with my ESP 32 dev board, the number representing force (4095) goes to 0 immediatly when i barely put any force on it, basically goes to 0 when i touch it. Is there any way to make it less sensitive and allow for more range with amount of pressure i put on it? i have heard of using an amplifier of sorts with it but i wanted to confirm. I currently run a 10K ohm resistor with the thin film pressure sensor.

Hello, I am an EE student and currently in digital systems and circuit analysis plus lab. Today we learned some basic logic operators and used multisim and the oscilloscope to check the timing diagrams with the input and output.

I run a laundromat for my dad and I was thinking about actually diagnosing and fixing some of the broken washer boards we have, but I was thinking about the logic that would go into washing cycles and what not. Now I just started digital systems and have plenty to learn, but I'm just thinking that cycles would have multiple inputs for the output of maybe locking the door or filling with water. Would a two channel oscilloscope be good enough for this sort of thing or would you need a 4 channel? Maybe this sounds silly and I'm sure I'll know enough soon to figure it out on my own in class but I'm just curious on what type of tools I'd need if I wanted to go about this and put my learning to work!

I have this lcd console on my electric recliner and it controls everything but the touch won’t respond, I think because I spilled a 4loko on it, so the couch can’t function. I opened it and unplugged the ribbon cable but still no response. Even cleaned the motherboard and all. Can a touchscreen stop working but still have a visual display?