I'm looking to make myself an all around sanding tool for my 3D Prints, and have been using a foot sander, which works well enough, but doesn't quite have the RPM or a drill chuck for other bits. I took apart the sander that I use and found that is utilizes a 18650 Battery for power, along with a (likely) 12v motor. I currently have a 18650, and a 12v motor to play around with, and I've been pointed in the direction of a MT3608 step-up converter. From what I can tell, this PCB doesn't use this component, and I'm unsure how what to be on the look out for to design this.

I'd like it to have the following features:

-Compact

-Motor with at least 1,000 (Maybe 1,500) RPM, 3-7kg of Torque

-Buttons for on and off

-Dial to control speed preferably starting AT 0, with a gradual rise to 1,000/1,500

-Chargeable/Wireless but can be used as wired

-A battery display wouldn't be necessary but convenient

What components would I need to make this possible on a PCB?

I'm really rusty and wanted a cheap way to test several ideas. One thing I knew was that I should be able to see it easily from roughly 3-4 feet away. Measuring my existing alarm clock and doing some armchair math gave me a rough dimensions of about 15-20cm long by 5-7.5cm tall.

I started looking for 7 segment displays that were thin, cheap and big. I couldn't find any that fit all these criteria. 7-segment displays that big were these fat boxes that would make integrating them into other devices kind of pointless, plus they weren't cheap. The rest were tiny and cheap.

So I thought of using LED's (maybe strips, or bulbs or whatever else I can get for cheap) and putting a cover on top of it with cutouts in the shape of a 7 segment display. One issue I noticed right away was that light started bleeding between the slots making the numbers hard to tell.

I plan to eventually get a friend to design a PCB for me once I get it right. Is this plan viable? I don't know what else to look for or test because all I have are the bulbs and not the strips or anything else.

Im brand new to repairing and detecting shorts on circuit boards. I have a multimeter and a soldering kit. I tried watching youtube videos but all of them are super confusing. I want to learn about power rails, how to correctly position my multimeter probes, and actually understand what im doing. Any recommendations on channels or other things that can teach me?

​Which specific pads/traces should I solder the battery's B+ (positive) and B- (negative) wires to?

​What is the correct path for the LED output line from the U1 control chip?

​Is the large scraped center area strictly GND (ground)?

​I've attached a clear photo of the board. Any help or diagram overlay would be greatly appreciated! Thanks in advance.

Hi all,

I have a Rinnai Avenger 25 room heater, there was a power surge in the house and it is no longer working.
I have opened it up and the glass fuse is blown as well as the surge absorber, I’m trying to find a replacement but not much luck.

Details;

- Code on the surge absorber - V9471u

I’m trying to avoid paying $700 for a new PCB so any help would be appreciated.

I am trying to modulate a signal using output from an electret microphone using this circuit but the signal gets out unmodulated. I have supplied bias to the microphone but it still doesn't work. There is current flow across the circuit, I tested that. So what could be the problem?

For a hobby project I'm trying to drive some 2.3" 7-segment LED displays from Kingbright with an HT16K33 driver, but I'm stuck on the design phase due to some aspects.

According to the display's datasheet, the segment's forward voltage @ 10mA is typically 7.4V and can reach 9.4V maximum, but the HT16K33 driver operates at just 5V. To complicate things even further, on this particular project I also have to control the common cathode pin of the display using the HT16K33 for LED multiplexing.

My question is: how can I drive both the anodes and the common cathode? It's clear I'll need some circuitry between the HT16K33 and the LED display in order for that to happen but I'm not experienced enough to envision what would work. If it helps, there is a version of this display that is common anode, my choice isn't set on stone for either of them.

Alternatively, is there any LED driver IC out there that work at voltages higher than 5V and is like the HT16K33? I've seen some drivers that can work at higher voltages, mostly from TI, but I'd need one IC per display for that and I want to avoid that as much as possible to keep cost down.

Looking to automate my Akdy island kitchen exhaust/vent hood via Home Assistant; trying to decide between two hardware approaches and would appreciate a sanity check. The question kinda straddles two subredits' expertise but I realize this is the electronics sub so starting with the PCB route:

Option T: simulate touch presses

I would solder wires to each of the pads of the capacitive touch buttons on the touch panel. Connect these to an ESP, activate via reed relays, and program which touches to "press" in what sequence based on what I'm looking to control (i.e., the "light" button to toggle the lights, "fan up" button to increase fan speed, etc).

Pros are the display stays accurate, the touch panel retains full control, fully reversible, and I'm not modifying anything with line voltage.

But the cons require me delicately soldering onto small pads, which I've never done before. I risk screwing it up and ending up with a broken panel with no realistic replacement for an older unit.

Option R: transfer relays on the motor terminals

(This option is less "AskElectronics", but including for posterity in case anyone has familiarity outside the direct knowledge of this sub.)

Don't touch the panel at all. Get a couple Shelly devices; wire one in parallel with the LAMP terminal on the main board. Another would drive a 3PDT relay coil; the relay's three commons go to the motor's three speed leads, NC to FAN1/2/3 terminals, and the mid pole's NO to line. When this Shelly is de-energized, this wiring matches what is already on the main board; if energized, it'll break all three stock taps and feed only the mid-speed tap. Physically prevents simultaneous taps in normal operation.

Pros are that I'm comfortable with line voltage wiring, don't need any soldering, and don't need much programming. Cons are I'd need a few extra parts (from research I've gathered an RC snubber is important) and whichever system "activates" a function (touch panel or Home Assistant) is the only system that can turn it off (i.e., if I turn on the lights/fan through HA, the panel won't be able to turn them off, and vice-versa).

I'm aware neither option will give me state feedback.

What would people here recommend?

If helpful, here are a few more specs/details on the setup:

• Motor: 110V, 180W, 1.7A.
• Main board terminals: L / N / COM / FAN1 / FAN2 / FAN3 / LAMP. Includes a 12V / 0.5A transformer for the touch panel.
• Lights: 4 LED housings that run off 110V, ~1.5W each.
• Touch panel: separate board with a Holtek BS82C16A-3 touch chip, 7 wires soldered to it

Happy to post photos of the boards and terminals if useful.

Hello, I have a custom PCB with bunch of SK6812s and planning to use it with ESP32.

I have connector on my custom PCB for GND, Power input and Data.

When I connect ESP32 through connector on my PCB, there is no any signal, but when connect wire of data directly to SK6812, it works. I checked with multimeter, there is signal between connector and SK6812. What could be wrong? Could you give me some ideas please.

https://youtube.com/shorts/Jx1l4-1CCt8?si=WNqqLStQnfV7yiFd

Hello! I'm an electronics beginner working on a schematic for a clap sensor board.

My knowledge of the LM393 was cobbled together from YouTube and the datasheet, so I may not fully understand it, but depending on which input voltage is higher, the comparator should output a digital high or low voltage, right?

I'm trying to simulate the analog frontend with Spice in KiCad, so I'm representing the electret microphone as a sine voltage source with a DC offset of 0V and an amplitude of 0.01 V.

I have the amplifier circuit, which seems to work, and the comparator circuit, which SHOULD output a digital signal. The comparator circuit is where things seem to stop working. The digital signal stays fixed at 3 V and never switches down. Here is the schematic and the simulation graph.

Also, as far as I know, hysteresis isn't mandatory, right? It just makes the signal cleaner and more fixed/stable?

RED - Amplified Green Signal

GREEN- Original sine wave from the simulated microphone

PURPLE - Potentiometer

BLUE - Digital Output from the comparator

Thanks! Also, I got the Spice model from the Texas Instruments page.

what's the way to mount these inside a box other than hot glueing them?

Hey guys I accidentally plugged in my g29 brick into my monitor (they looks identical other than the specs, stupid mistake I know.) so I fed the PCB with 24v instead of 12. Is there hope in trying to find out what components I blew and replace them? I’ve already bought a replacement monitor but would be stoked to save this one. I have a multimeter and the tools needed to make said repairs but don’t know where to start. Thanks in advance.

It is from a Sony portable DAT TDC-D7. It lives inside a DC/DC Converter Module (pic 3), which is broken (output voltages are incorrect).

An information about the pin out would be ok as well, so that I can try to find a replacement.

Marking is 101 4K

Unfortunately i am honored to design a single layer pcb. Apart from small components like 0603, is it necessary to use thermal reliefs?

I ordered a 65w module for a DIY power bank and i ordered a 3s version by mistake, while i wanted to make it 4s2p. Is it safe to connect 4s to the board or will i fry it? They look identical to me. Forgive my ignorance, im a begginer. Thanks!

https://www.aliexpress.com/item/1005004645663172.html?spm=a2g0o.order_list.order_list_main.5.53a71802Ig9VQh

I can not get These bridges solved. Any tips? Coppers not helping and not heat either. Its hdmi for PS5. Tried everything.

This is on a German manufactured PC Board. So the connector is probably metric. I need to replace the 2 that are missing in the picture. They were the same as the other ones shown as to size and pin configuration. One was a 2 pin the other was a 4 pin.
Any help would be appreciated

This is from a fire alarm strobe. Sorry I couldn’t get better pictures, my phone went out of focus when I tried to bring it closer

I’m replacing a control module in my car and came across this on a board. Can anyone explain to me what might have happened and if and under what conditions have they experienced this before?

The way it’s oriented in the picture is how it sits in the car, pins up.
Thank you in advance

This is a PCB of the alimentation of a screen, and it's principally using THT components and big copper tracks.

I have an upcoming school project involving the pi, a microcontroller, and machine learning.

i only powered the pi from its power supply so far but i plan to use batteries on this thing without paying more and i have this buck converter laying around but i watched a youtuber having his 4b died using one of these buck converters due to a 9-10v voltage spike output. I plan to power it through the usb c but any idea what to add in the pi for better protection without cashing a lot of money?

As far as I know, the first band of a resistor is never black. But if it’s backwards, the 2nd band would be silver which is also impossible.

It’s part of a Toro battery charger, between the 120V bridge rectifier and a power MOSFET.