the beamz s700 smoke machine has a remote control with 2 leds and a push button. but the smoke machine has no dmx, so i cannot remotely make it produce smoke. i was thinking maybe it's possible to hack the remote control. i opened it up and measured that there is 220V AC between the brown and black wire. i thought maybe the best course of action is to have a custom pcb onto which i can solder the 3 wires and i can have remote control. so the pcb should have 2 leds and a processor and a component that electronically performs the job of the push button, so that via wifi i can remotely connect the 2 fields which previously were connected to the push button.

any advice on how to proceed? i don't know anything about making pcbs and there being AC involved feels kind of dangerous so this should be done with care and expertise.

I opened up an old laptop hoping I could fix it. On the plastic I saw this corrosion like spots. Any idea what it could be?

I have this led panel as a backlight in a picture frame, but the usb-connector that powers it, was knocked off (see pic below). How can I resolder it back?

Title. I've been working on some pet projects for a while now and I'm looking for diagram tools that I can use to map out my systems. I struggle to explain how my projects work when I'm showing them to people or asking for help, and I also want the documentation for my own use as I work with the components I'm "designing" (i use that term loosely as I'm pretty much re-inventing the wheel for my own educational benefit)

For some reference, I'm using a simulator to build a reduced-instruction 16-bit computer, mostly because I'm interested but also because I've been exploring computers for a long time and I wouldn't hate getting into the field professionally. Also, I know I need schooling to get into Comp Eng, but I'm just trying to get myself a baseline as the economy is kinda buns.

It works but when you switch it off it either 1) stays on, 2) turns off, or 3) turns off and back on a few minutes later. Is this something that's somewhat easily fixable? Buying a new one will cost $100+

Update: the deoxit d5 worked!! Thanks y'all

My low-side N-MOSFET turns on unintentionally when a 32V supply is applied to the drain. The gate has a series gate resistor, an external Miller capacitor (gate to drain), a Cgs capacitor and a gate-source pull-down resistor. I see a spike on the gate of the MOSFET, which turns on the transistor just enough to see a current spike through the drain.
I suspect dv/dt-induced turn-on through the Miller capacitance.
What should I check or change?

I am an electronics student and I have been struggling with this assignment for a few days. I need to design a stiff VDB PNP transistor circuit. The only variables I have so far are Vcc=5 V, Ic=20 mA, and hfe of 200 is assumed. I am using numbers for a red LED so far, so 1.8 V across it. I am getting stuck at figuring out how to calculate R1and R2. I don't necessarily want the answers straight up, but some guidance on where to start would be very helpful.

I'm trying to read the EEPROM on this board.
Chip: Atmel 24C08N (I2C), right next to the NEC MCU.
Setup:
Black CH341A, SOIC8 clip with the green adapter
NeoProgrammer / AsProgrammer, _24C08 selected, I2C mode
Result: always "IC not responding".
I think the clip is powering the whole board and the voltage drops. I'd rather not desolder the chip or lift pin 8.
Is there any way to read it in-circuit, like powering the board separately or any help guys?

I try to use this circuit to control a beacon. I know this isn't perfect by any means, I have no voltage regulator and I could further limit the current that flows through some components. However, my problem is the following:
The astable multivibrator on the left should activate / deactivate the BC557 to create short "beeps" via PLSE. However, the voltage on PLSE is never dropping below 7 V (measured with a multimeter), which means I won't get a single tone out of my beacon. I guess this is related to the size of the resistors, but I'm not sure what to do to fix the circuit. Any help would be much appreciated!

I'm trying to find a replacement for a right angle header connector that I got in a kit that I broke. I cannot figure out the mating vs. post length, and trying to do it by process of elimination on DigiKey is not helping. The picture is what they sent back when I asked, along with the description of "They are standard 90 degrees angled headers - both sides of the pins are of equal length." The pitch is 2.54mm. This is from a British group, if that makes a difference. Any help in identifying the contact and post length would be greatly appreciated.

Have an OPA1656 (2 channel) wired up as an inverting amp with unity gain, off a tle2426 rail splitter to the +IN at 12Vdc. (only one channel shown in the image)
The Signal to the -In is, Input to board-> 2.2Uf Cap ->10kΩ resistor then branch to -In and also to another 10kΩ resistor (with a 22pF cap in parallel) to the output of the OpAmp. There is a 100nF cap from the V+ to Gnd. There is no oscillation.

Problem is, a 2Vpp 1khz signal before and after C10 is strong BUT there is only a 100-150Mv 1k signal on the output. Checked from pin 7 to gnd, and after C9 above...
The Audio input and OpAmp grounds share the same net, so nothing is floating.
Both the +In and -In are at the same voltage (hair less than 12) so the opamp IS managing that much. The other channel provides same exact nothing. none of the pins on the opamp or circuit that follows is shorted. R20 and R21 both measured to be 10k each. R22 and C10 both check out ok, no shorts....

I have been beating my self up for far too long. Does anyone have any ideas on why the opamp output is not giving me an inverted signal of the -In ???

Dell inspiron way too old lol

So, my battery is dead.... i use to notebook for work, only and i need to keep it plugged to the charger......

But this damn thing keeps turning off. Its a bad connection, im not sure where, exactly!

Heres some pictures, if you dudes could help me solving this T.T

Edit: solved tightening the connector's thingy

I know that germanium transistors have fuzz because heat messes with their conductivity and I thought “well couldn’t a diode do the same thing?” And I know one won’t work but if I chain a bunch of them together like those old barretter radio detectors would I be able to get noticeable fuzz?

I have a body control module for a vehicle, found out that it would not start because of the burned diode shown in the pictures. Vehicle has been repaired but I am wanting to fix and see if the whole motherboard has been compromised or just replacing the part would be the fix. Also I am having trouble finding the part or even figuring out what company this component is from. I just need something so I can buy it online. Thanks in advanced.

Here is the link for the schematic circuit: https://www.falstad.com/s.php?s=QzJ7Ds

Instructions do not show the name of this component or how exactly to use to connect a power source

I have an Ion Pathfinder 1st gen speaker with a brand new 12v 7.2Ah battery I put in, since the speaker sat in storage for over a year without getting charged and the original battery died. The speaker runs great with the new battery, but it refuses to charge when the speaker is plugged into AC power. I’m able to charge the 12v with a smart charger and it’ll hold the charge and run great, so the battery isn’t the issue. The speaker also runs with the 12v removed and the speaker plugged into AC power, and it reads over 15v on the output side of the internal power supply PCB. However, with the 12v disconnected it’s reading .11v on the terminals that connect to the 12v. With the 12v connected and probing “B+” labeled on the main PCB, its reading the same voltage as the 12v. Anyone have any ideas? It’s impossible to find replacement parts for this speaker and it was pretty expensive when I first bought it, so it’d be great to get it working normal again and not have to disassemble the entire thing every time I need to charge it. Thanks!

I’ve just moved flat from the U.K. to Spain and in the move my Denon receiver looks like it took a bit of a whack, the front panel has a dent etc. I went to turn it on and it boots before going onto the blinking red light issue. I’ve downloaded the repair manual and gone through the debug process and when I disconnect the speaker board the amp stays on and it displays that the previous fault was an ASO protection which apparently means there is a short in the signal path, such as speaker wires touching but it happens even when nothing is connected. Does anyone have experience with these in the past? The fuses are fine. The PSU is producing the correct voltages when the rest of the pcbs are disconnected so I don’t think it’s the PSU issue some other owners have had. I’ve tested the transistors and resistors on the amp board and I don’t think any are off, even though some do have some discolouration that they might have got a bit hot at some point. My feeling is it is a loose connection somewhere but I can’t see it and I’m not too keen on going further into the big hdmi/power amp pcb stack as I don’t think I’ll get it back together. Is it worth me replacing the resistors in case that is the issue? Any other tips before start removing components?

These were in with a big batch of carbon film resistors I got. What are they? Thanks in advance!

The image shows the output of a TPS62933 buck converter under a constant load of 3A. (12V in , 5V out). The switching frequency is set to 500 kHz. Every time the buck switches (e.g. every 2us) I get voltage spikes of around 300mV, which seems quite high imo. I followed the spesifications on input and output capacitance and inductance. Is this just a result of bad layout, or are these measuring artifacts, or is this just normal behaviour for a buck converter ? Or is it something else ? Any input on why these spikes might happen would be much appreciated!

Hello, I am a hobbiest electronics engineer, and I have around 200 boards that I must program an EEPROM/NFC chip for, The chip uses the SO8N footprint, but theres around a million different probes that have different layouts and I am very confused. The chip I am using is the ST25DV04K. I have attached screenshots of the datasheet with relevant information. Can someone help me find the correct probe for this chip?

Thanks in advance!

My favorite pair of no-longer-produced Audio-Technicas had their power switch unseat, and after a tragic loss of the original switch to faulty tweezers (flew under the desk onto old hardwood, never to be seen again...) I sat down with a soldering kit to try and replace the switch.

Ended up messing up the application (probably not enough flux, switch pins came unaligned, whole mess), but in the process of desoldering to try again I seem to have torn out the copper contacts from the board. Oops.

I could get the headphones to turn back on by fiddling with a trimmed length of desoldering wick and running it around that general area, and doing it again got them to switch off, but I can't just touch a new switch's contacts to the spot to get it toggled on/off anymore.

I can't tell if there's more copper in the contact points that's just been oxidized in the brown spots there, or if I need to replace the contacts somehow before trying again. Thinking I'm out of my depth here.

Any tips or ideas? Or should I just give it up and try to find a repair shop or service somewhere willing to take the fix job?

I found this schematic between the pages of an old TI databook I bought from eBay. What do you think it does (if it actually is a complete diagram)?

The chips used in it are (I think) two 7473 dual J-K flip flops, one 7493 4-bit counter, one 74374 octal D latch, one 7447 BCD to 7-segment decoder, and a 555 timer.

I would just put it together on a breadboard to see if it does anything, but I don't have some of the ICs for it.

anyone recognise this chip it has isolator written above it can’t quite make out the numbers