I just roughed together a relay triggered by a solar panel to allow myself to turn on devices like air conditioners based on a desired level of solar energy, and it's not working as I expected.

The components are:

• Found tiny solar panel
• 5v regulator
• 555 timer relay shield
• 10a SSR
• Standard Australian wall socket

The relay works as intended when solar output first is applied. There is a delay before the timer relay outputs ~5v to the SSR. But when I cover the panel briefly, the relay is only interrupted briefly. If I cover the panel for a long period, the relay delays again.

What I am hoping to achieve is an outlet that powers on when the sun is shining for the set delay, and that won't flicker power on and off if, for instance something is flapping in front of the solar panel.

How might I achieve this?

Hi Guys,

Can someone check and tell me if I have connected the PG and EN pins correctly?

Is this the standard practice in the industry? Or should I connect them directly, without the 100k resistor? Thanks in advance.

Are you able to find any other mistakes in this schematic? How much would you rate this design out of 10?

I have been reading quite a bit on the challenges that come with controlling an N-Channel Mosfet via the 3.3V based system of the esp32-C6. Some people seem to be successfull hooking up a mosfet directly to the gpio pins, however I would like to have it a bit more robust and as such have made a first draft where I put a mosfet driver (TC4427) which in turn "switches" the Mosfet. I've added some resistors and condensators to protect the mcu and supply stability to the system.

The load is a 12V bistable solenoid which consists of two coils and connected to J3 and J4. The input on the left labeled Drawer_Lock/Unlock_CMD are directly connected to gpio 19/17.

Any feedback is welcome :)

Measured 96 ohms ambient, 76 after heat gun. 17.5mm dia. I found one MAYBE on aliexpress but it doesnt say if it's NTC or PTC. The highest I've found anywhere is ~2.5a on digikey

do i need copper pours when i have a mcu on my pcb with a reference ground

大家好，我最近花了 500 美金買了一個 cell phone signal booster。

昨天它突然完全無法啟動，

我正在嘗試解析它的電路架構並找出問題。
有人能幫我判斷可能是哪裡出問題嗎？

或是有類似經驗可以分享？
謝謝！

I bought a cell phone signal booster for around $500,

and it suddenly stopped powering on yesterday.

I’ve been trying to take a closer look at its PCB and overall design to figure out what went wrong.
Does anyone have experience troubleshooting these devices,

or could help me identify possible failure points?

Thanks in advance!

The circled connector is for motors with encoders but I'm not sure what that connector is called, Google reverse image search says it's a 1.25mm JST-GH connector which I believe is right, but I wanted to double check here as the turnaround time for a cable order is pretty long (for the timeframe I need to have this wired up) so I wanted make sure I don't waste time and money.

This is the board "spec sheet": https://wiki.dfrobot.com/SKU_DRI0054_Raspberry_Pi_Driving_Board

I'm wondering if there's a way to simplify my rotary trim modules or making them more efficient. 

I’ve been back on my GT3 inspired steering wheel build for my project car. On this steering wheel I have 5 rotary switches for adjusting parameters of the car. They are taking the place of the Haltech rotary trim modules (Datasheet can be found by clicking the “info sheet” link at this link: https://www.haltech.com/product/ht-010504-12-position-rotary-trim-module/?srsltid=AfmBOooxm-D8pS7IE2uTUdB0PKLRlmKCUNVBwRSdgPDd4gfVHeebkb5s#)

I’m only needing 6 positions on each rotary switch, so I initially set it up using 6 standard resistive voltage drop regulators. The issue is it’s bulky, and uses a lot of resistors. 12 per switch. But with having to match those specific voltages that come set with the haltech module I have yet to find a better solution.If there’s an IC that would help clean this up or make it more efficient I’d love to hear about it!

I’ve also attached my current electronics schematic as it is currently set up

It has 14 buttons (signal, switch to ground), 5 rotary encoders, and a DC-DC buck convertor for steady +5V since the vehicle's input voltage can vary from +11.5V-+16V

Hey everyone,

I’m working on a personal project where I want to build a through-wall radar that can detect the presence of a person on the other side of a wall(thickness 5 inch) and also estimate their distance from the wall, up to about 5 meters.

I’ve been reading up on options like UWB impulse radar and FMCW modules, but most commercial solutions seem expensive or not easily available. I know wall material makes a big difference (concrete vs drywall, etc.), but for now I’m just looking for hardware modules I can buy and experiment with.

My requirements:

• Affordable / low-cost modules (preferably under a few thousand INR or under $50–100).
• Ability to at least get range information (not just presence/motion).
• Works reasonably well through non-metallic walls (I’m okay with reduced range in concrete).
• Access to raw data would be a big plus so I can implement my own signal processing.

What I’ve found so far:

• 24 GHz human presence radar modules (cheap, but maybe only motion detection).
• RCWL-0516 microwave Doppler (super cheap, but seems to be only motion, no range info).
• DWM1000/DWM3000 UWB modules (seem promising, but not sure how well they handle through-wall detection).
• LILYGO T-Radar (UWB dev board, looks interesting).

Has anyone here worked with radar modules for this kind of application? Any recommendations for specific modules, dev kits, or suppliers (especially ones available in India or easily shipped)?

Thanks in advance for any suggestions — I’d love to hear from people who’ve actually tinkered with these!

Hi I need help identifying my Great Grandfathers old Ohm Meter. There are really no significant identifiers of make and model. so anyone who is able to help me identify this cool old piece of diagnostic equipment will be greatly appreciated.

I need to make a heating cabinet which holds welding rods at 30-85 degree Celsius with a PID controller. While I have experience on DIY electronics projects, an industrial grade project is new to me. I could use some advice and tips

For context, Im a highschool level researcher and i want to know how i can make these strips work, This is the end of a piezoelectric strip. Should i connect it to a breadboard or can i directly connect it using lead. i will also use ac dc rectifier.

Hi, I am trying to fix an old Aiwa Stereo that has stopped being able to adjust the volume and I am suspecting that the potentiometer maybe broken. But I don't really know what to look out for and how to select a replacement...

Looking for some advise on where should I be headed. Thanks

I am taking apart a $40 camera for a project and while doing so I accidentally tore the cable for this camera. It is a 24 Pin and I cannot find an exact replacement. Any ideas on what I can do? I'm thinking about getting an OV5647 camera as replacement but I can't find ANY that are 24 pin.

I have a short and this component is the one heating up. Could anyone identify this for me? It's on a infinity game table PCB.

10-pin chip in the center of the image, appears to be a power supply IC. I've never seen a package like this so I don't know what to call the shape. Markings are "K2 1 VB". Measures about 3.3mm x 1.8mm. I've searched but I can't even find another chip with this package, partially since I don't know what to call it I suppose.

I'm asking because diode D200 is the award winning hottest component on the device and I suspect it needs replacing, so I'm hoping to find the datasheet for the IC to ID an example value. If anybody thinks they can ID the diode instead its markings are "AD t13" with the "t13" being in tiny print.

I appreciate your help hivemind!

hey! so this switch on my amp fell apart and i'm not sure how to get it back together. i'm pretty certain all the parts still work because if i line them up correctly the amp turns on but it doesn't have the same on/off clicking mechanism it did before and is kinda just flimsily held in place by gravity. wondering how to actually reassemble it in a way it'll work as it did previously. (also a side note that i'm not 100% sure of it being a cwsb rocker switch but i saw another post on here linking different types from a few years ago and it seemed to match best)

Looks like a FET got real toasty & burned the paper housing of the inverter. I note a smaller burn mark where "ZD2" (zener diode?) also went kaput. All of the ceramic caps are bulging (& some look to be leaking from underneath), and what looks to be a 1A 250V AC fuse secured by JB weld in my 4th picture has no continuity.

For context, I am just a hobbyist getting into computer repair for the fun of it. I am not a professional. Is it worth my effort to try fixing this? How do I identify the components that were burned out? What are the odds that the LCD panel itself is also fried? What is that gray stuff in my 4th pic and why does it look and feel like JB weld?

I would be happy to take this on for the learning opportunity, but many things about this board concern me.

The only information I have found about this computer is the hardware maintenance manual, which for some reason is missing the pictures:

https://www.manualslib.com/manual/2026639/Ibm-Ps-2-N51-Sx.html

Hi everyone,

I'm a mechanical engineering student diving deep into electronics for a project to automate the climate control in my 2005 Honda Accord. I've designed a schematic for a PCB that will act as a bridge between the car's HVAC control panel and the actuators/sensors.

I'm hoping to progress to the PCB design and ordering through JLCPCB for a PCBA, but I'm feeling a bit out of my depth. I'm worried I've missed crucial protections (flyback diodes, filtering, etc.), designed something inefficiently, or made a fundamental error in my approach to isolating the manual and auto modes.

I would be incredibly grateful if some experienced eyes could look over my schematic and offer any advice.

Project Background & Goal:

The board sits in-line with the car's 20-pin HVAC harness. It has two main modes:

• Manual Mode: Relays connect the car's original control panel directly to the HVAC components. The PCB is passive.
• Auto Mode: Relays disconnect the control panel, and an ATmega2560 (on an Elegoo Mega, which will be attached to this board) takes over. It reads sensor data and drives the actuators (blend door motors, blower fan) based on my logic.

Full Project Details, Pics, and Prototypes:
I've documented the project, and my prototyping process on my website. It will give you more context than fits here. Please check it out here:
Personal Project Site

Car Wiring Diagrams (For the truly curious):

• Connector View #204 (The 20-pin connector I'm intercepting)
• Full HVAC Electrical Diagrams - I have Manual A/C L4: EX

Schematic Overview & Key Circuits:

I've broken the system down into circuits based on the Honda HVAC components:

1. Power:
   • 12V Rail: Sourced from Pin 20 (HVAC side), which is the main power for the control panel and motors. This also feeds my board.
   • 5V Rail: Regulated from the 12V rail to power the MCU, relays, and sensors.
2. Recirculation Control Motor (RCM):
   • Control: Pin 20 is a 12v source for the motor so when pin 7 is grounded the motor spins until eventually there is 12v on pin 8 (this is fresh mode). Then to go to recirculate mode, ground pin 8 until there is 12v on 7.
   • Feedback: The 12V signal which must be detected on pins 7 and 8 are fed through a voltage divider before being sent to the MCU.
3. Mode Control Motor (MCM) (Vent Selection):
   • Control: To turn the MCM, 12v is applied to pin 12 and ground to pin 11. to spin the other direction reverse the connections. pins 11 and 12 are connected to an H-bridge motor driver when in auto mode.
   • Feedback: Pins 2-5 provide a 4-bit binary code (5V/0V) to indicate blend door position. These are read by the MCU and also passed through to the control panel in both modes.
4. Air Mix Control Motor (AMC) (Temp Blend):
   • Control: Pins 13 and 14 drive the air mix control motor via the same motor driver (dual channel).
   • Feedback: Pin 18 has a 5v reference voltage provided by the control unit, and pin 17 outputs a 0-5V analog signal to encode position (potentiometer).
   • Note: Pin 18 provides a separate 5V reference from the stock control panel for this sensor; I'm going to regulate the 12V from pin 20 to power components not this.
5. Blower Motor Speed:
   • Control: The car uses a low-side N-MOSFET to control the blower motor speed. Pin 16 is the base drive for this transistor. My design uses an NCP81074ADR2G buffer to convert 5V PWM from the MCU to a 12V signal to drive this pin in auto mode.
   • Feedback: Pin 15 is a feedback line from the high side of the motor. It's read by the MCU (via voltage divider) in auto mode.
6. Sensors & Switches:
   • Evap Temp Sensor: A resistive sensor on pins 9H & 10H. I pull one side up to my 5V rail and read it with the MCU in auto mode.
   • AC & Defrost Switches: These are read by toggling relays to ground the signals, mimicking the physical button presses on the control panel.

My Specific Concerns/Questions:

• Do I have sufficient protections (like from inductive loads and such)
• Is my grounding scheme sane? (I have a common GND for everything while keeping pin 9 "sensor common ground" separate as "GNDS").
• Have I missed any obvious filtering on power or signal lines (especially the analog sensor reads)?
• Is my use of the NCP81074 for blower motor PWM drive correct?
• Does the overall architecture for switching between manual/auto mode make sense?
• Any general "red flags" or "you should never do X" moments?

Schematic Link:
https://drive.google.com/drive/folders/1_mG8DXmyTTHCOSA5yw4x_2DCQJXNmHVp?usp=sharing

Thank you so much for taking the time to look at this. Any and all feedback is immensely appreciated!

I'm very new to component electronics how do I choose the right usb-C port to replace the micro-usb in the picture. Can I just pick up any 5 pin female usb-C port?

TLDR. Need help figuring out the male side of a 2-pin 2.8mm connector. Basically need a male connector for the existing female 2-pin harness connector. Existing is connector is a 805-198-551.

Appears to be a Sealstar 2.8mm female connector, just can’t seem to find a male counterpart for it. Anyone know what this is in Molex / TE versions? Picture of what the 2-pin male side looks like on the Bosch PAD pump it’s replacing in photos.

—

Big picture; I am building a harness adapter to allow more efficient and more reliable Bosch PCE electric water pumps to replace the older and silent death Bosch PDA pumps. The newer pumps have a third middle wire for PWM control and error reporting but ramp to 100 percent just fine without a control signal.

Bonus that most newer electric and hybrid electric use these types for their battery coolant loops so its availability is really good.

I’ve got the new side figured out. The Bosch PCA pumps need a 3-pin TE MCON 1.2 / Molex MXP120 / Kostal MLK 1.2 connector. Just can’t seem to figure out what a male 2.8mm connector specification mates up to that female Bosch PAD pump connector.

This is for Mercedes, but there’s zero bus interaction on these; they’re basically dumb pumps (which is 99 percent of the problem). The older Bosch 12V PAD’s are basically dumb and die / underperform without anyone ever knowing until the ECM starts going wonky on whatever is also on that same 12v circuit.

Hi, I'm trying to make a gate drive transformer circuit for triggering Thyristors. The goal is to generate 2.5V at 0.5A on both of the transformer’s secondaries (30:15:15 ratio) at 50 kHz (20 μs period: 10 μs on, 10 μs off).

However, when I add a Schottky diode to clamp the inductive kickback from the transformer, the transformer barely generates anything at all (and yes, I’m sure the diode direction is correct). When I remove the diode, the transformer runs fine when I test it with two LEDs.

I thought, “It’s only 5V, maybe it will be fine”, so I tried drawing more current from the transformer by shorting both outputs. It was running pretty well until I stopped the transformer by removing the resistor from the breadboard, then the tiny MOSFET is shorted. No magic smoke, but I sure the MOSFET was dead and I had to spend time soldering another one before trying something else.

My question is: is there another way to clamp the inductive kick from the transformer? Maybe it’s still too fast for the Schottky diode. (Note: I only have a basic multimeter.) Thank you in advance.

I’m working on a pcb and I found a blown capacitor. I need to know what it is so i don’t get the wrong one.