Ask Electronics

Since MOSFETs have a gate capacitance you'd want to limit the inrush of current from the output of a microcontroller to prevent it from getting damaged prematurely. That's what gate resistors are usually good for.

Another thing is that most MOSFETs don't fully activate with a gate voltage below 10V (n type) so usually a microcontroller pin isn't good enough for switching large loads.

I have a 24V system and have made a voltage divider using two 10k resistors to step down 24V to 12V as gate driving voltage which is pulled down with a weaker MOSFET. The power MOSFET essentially ends up with a 10k gate resistor this way meaning it will take a bit longer to fully saturate.

Is too high harmful? In this situation the load is a heater that activates when the room temperature drops below 18C and deactivates when it gets above 22C so fast switching is not an issue.

I recently came to the realization that I've been kinda punishing myself with cheap no-name solder that is really difficult to work with.

I reluctantly bought this (rather expensive) lead free solder for around $25 and the difference really took me by surprise - it melts and flows so easily!

Kinda got me wondering what everyone else has been using for solder, or what's worked well for you so far at least?

I'm an EE by trade focusing on embedded devices, but most of my work is in relatively low-power STM32 applications. When I stopped following developments in hobby kits, it was mostly Arduino Unos slowly driving I2C OLED displays.

Now suddenly, there are embedded Raspberry Pis and ESP32s doing realtime facial recognition and video feeds.

Is there a good place to look to catch up on what's now possible with these embedded devices?

Also, while I enjoy the ease of the hobby kits, I'm also interested in more mass-production-focused solutions.

Trying to repair a Hyperkin Duke Xbox controller where the left trigger doesn't respond. Found that the resistance of this potentiometer doesn't change when it's moved, so I'm looking to replace it. I'm a novice with this stuff though and I'm having trouble identifying it. Any help is appreciated.

Hi everyone!

I'm trying to control a "dumb" led light strip segment with an ESP-01S. This is fairly low current, the strip will pull 150mA-200mA max (depends on... artistic? needs).

I have two NPN transistors (2N2222), one to control the 12V supply to the white "channel" and the other the red+blue (don't need the green).

I had to pull-down the gates as I had some flickering, and it works perfectly if I manually connect the GPIOs after the ESP-01S boots.

The ESP will boot if I have the RX pin (GPIO03) pulled down on boot, but not if I pull down any of the others.

I'm not smart enough to come up with a way to have that extra pin I need to be high only during boot, while the gate it's attached to needs to be pulled down...

Any thought, other than getting something with more IO pins?

I'm learning about electronic components. I believe this is the part which has broken and made this heating pad unsafe to use. Well, unusable, not just unsafe lol.

I'm planning to make a modular synth from scratch, but I need to start with the PSU. Do you see any issues with this schematic?

The main difference between this design and traditional linear PSUs is the replacement of the transformer/rectifier/filter circuit by Mean Well IRM AC/DC converters. The linear regulation circuit is basically the reference design for the 78xx/79xx.

Do you think there would be an issue once scaled? The AC/DC converters have a lot of headroom, as I plan to make up to 3 regulation circuits like so:

(the regulated outputs will actually never go nowhere near 1A per rail)

cross-posted from: https://lemmy.world/post/9052986

I've got an antique lamp that needs a new switch knob, but then scope-creep happened and now I want to "smartify" it. I started off thinking that, since it has a metal body, I'd install a capacitive touch switch, but now it's escalated to wanting to put an ESP8266 or ESP32 in it to handle the capacitive sensing, Home Assistant connectivity/control, and maybe even switching to some kind of low-voltage RGBW LED instead of a 120VAC Edison-base bulb (especially since I suspect I'd need some kind of antenna sticking out the top, since the metal lamp body would presumably otherwise block the ESP32's signal).

The lamp, BTW:

(Apparently it's a Genie lamp by Laurel Lamp Company, in case anybody cares. Also, the lamp shown is the same model, but it's not my picture.)

I'm aware that the "easy" way would probably be to just screw a smart light bulb into the socket and wiring I already have, but (a) I'm picky about both avoiding "clouds" and using FOSS firmware, and I don't feel like sorting through the junk on Amazon to figure out which ones can be flashed with ESPHome, and more practically (b) that wouldn't let me turn it on and off just by touching the lamp body, which is what sent me down this rabbit-hole in the first place.

Anyway, I know this sort of thing can be done, but I'm not completely sure how. I know I could figure it out myself eventually, but I figured it couldn't hurt to ask for advice in case somebody happens to be able to rattle off part numbers for the whole BOM off the top of their head, or knows exactly the right ESPHome howto to point me towards, or something like that. Any advice is welcome!

(In case it's relevant: my level of experience is that I programmed an Arduino to run neopixels (WS2812 RGB addressable LEDs) once, I've flashed ESPHome on some Sonoff S31 smart switches, and I'm a software engineer by trade but have never worked on anything IoT related professionally.)

I want to replace one half of this with longer wire, but I am not confident about the name of the connector used.

Image of JST-XH included to convey size. Ruler is metric.

So, there are these great 32700 LiFePO4 batteries that showed up in my local industrial market. For like USD 2$!

However, there are no LiFePO4 chargers available. The vendors assure me I can "totally use" a 4.2V Li-ion charger, but I don't believe them (although the cells test as being in good shape).

I whipped up a 5V system with a buck converter managed by an MCU. It turns off the buck converter that charges the battery, measures the battery voltage, and if it's under 3.6V it enables the buck converter. Repeats every few 100s of milliseconds.

Did I overengineer this? Could I have just used a linear voltage regulator that outputs 3.6V (or a Zener), and a current-limited 5v power supply?

Charge speed is not really important in my application. Anything under 4 hours is great. Frankly, I'm just trying to phase out the less safe kinds of lithium cell in my lab.

I had an old USB Oscilloscope (StingRay), it's 20+ years old now.

Bought a OWON HDS242 with the hope that I could view some stuff on it's screen, but still hook it up via USB to the computer and do some voltage data logging. It doesn't seem to work like I would like it to.

So I've learned what I want is a Data Logger and not an Oscilloscope.

Can anyone recommend a good USB Data Logger that won't break the bank?

Decent bit ADC, and something that can get down to the 1us.

Doesn't need to be high voltage.

Cheers,

Just exploring about this tp-link XN020-G3v router. I'm mostly interested in connecting to the UART, won't be tinkering with electronics of it, but out of curiosity I tried to search what these chips are. and I couldn't find much about the big chip. Can anyone describe the 4 main chips on it ? Best would be datasheet, but whatever information you can provide.

I suspect

1. bigger one(ECONET EN7526FCU) is CPU/SOC, (couldn't find datasheet/specs). Can anyone provide details ?
2. MT7592N is definitely network IC(found datasheet)
3. Le9641PQC is network IC. required for VoIP. (found datasheet)
4. AJ194 (backside) is flash ? How to tinker with it ?

I migrated here in the US (specifically in San Bernardino, CA). Quick Intro: I'm a graduate electrical engineer; honestly, I really don't have that much experience and not even a decent internship experience due to covid, resulting in an online OJT. Do you think doing an internship here in the US is the way to go? If yes, what kind of advice can you give when applying like tips and what things should i look into, and what kind of internship should I start with? Thank you, any advice are appreciated :))

hi again, since i had a bad idea in my last post i wanted to try again to get some feedback i could understand and apply.

the idea is to make a vacuum (the appliance) play a few seconds of r2d2 sounds. the vacuum is hauled around on the scaffolding on a construction site and wont be necessarily standing upright (while idle or in used).

my original idea was to have some kind of trigger through a sensor (SW-18010, or something) that draws zero power (like a tilt switch, but position independent). that trigger should pull a pin high on the dfmini mp3 player (cheap player board) which in turn would play a few audio files while powered.

so sensor -> 555 astable -> df mini player -> speaker (piezzo maybe).

any ideas or pointers? is the idea of zero power in this case even possible (never used the 555 before), is maybe a attiny a better idea while in deep sleep?

battery life of 1year + would be ideal.

My Google-fu has completely failed me. I've got an RGB addressable led curtain. It has 20 strings of 20 LEDs in a square arrangement. I initially assumed it had a wire feeding led data back up, to go to the next drop. On checking however, they are T jointed.

Apparently the address is hard coded into the RGB controller in the LED. I've found a few places where others have talked about them. I've also found that adafruit had some available,, unfortunately they lacked any info on how they are programmed, or where to source them from.

https://www.adafruit.com/product/4917

Anyone got any info on what the chip name of these is? Even better if you have any info on how they are programmed etc!

To all the electronic nerds out there: I am trying to trigger a 555 timer by movement in a random direction that also occurs randomly and any change in position should trigger the 555. AFAIK tilt switches are not useable here. Does this idea make sense?

Ferrite core In orange, spool in blue.

Would there be a voltage generated by movement if the core is suspended by some kind of spring or rubber band?

The idea being to play a sound from a df mini player by pulling a pin high for 3 seconds.

Im building a flashlight and i want to test if a fan in it would be a good idea but the flashlight is really small so i would need a motor thats smaller than 1 cm preferably. I found really good ones at maxon group but unless you order them in bulk(1000+ units) they cost like 400€. So do yall know anywhere i could find them? Thanks in advance! (Edit: Im a complete baffoon and forgot to specify that preferably i would need a water resistant fan. I assumed this because bldc motors without drivers are wter resistant)

Does anyone recognise these power supplies? They're cheap AliExpress led drivers and I want to change its output voltage to around 22V from 12V. I've read that the way to do this is to adjust the REF voltage on the IC that controls it. It's a KA3845 but I don't understand where that reference voltage is regulated. One voltage is feedback from the output where then other should be a reference.

What would be the best way to approach this? I can't find any schematics on these boards unfortunately.

Thanks.

I have a 3D printer and have a special filter that has two 24V blower fans that are connected in parallel. Unfortunately my printer doesn't have the proper connectors for the fans. So if I purchase something like this power jack adapter I know the adapter is 12V not sure if that would make a difference. Anyway if I connect the female part of that adapter to the fan cables and plug in my laptop charger which is rated for 19v to 24V would that be ok?

If those adapters are fine, should I just purchase 12V blower fans instead?

Hi,

I recently bought a few pre-made amplifier modules for an 8-channel amplifier project (for a sound installation).

The amp is based on the TDA7294 chip and is rated 85W nominal. Now I'm looking for a power supply, but I'm a bit lost (this isn't really my strongest field, to put it mildly).

Do I just need to add up the output power, 8*85W = 680W, or could I get away with using something smaller, like a 300W or 300VA?

Also, the seller said that you need to use CV power supplies, CC won't work and kill the circuit. Does that mean a switching supply can't be used?

It looks like the module has a rectifier and smoothing caps integrated, so I could potentially just use a transformer, right?

Best, N

I have to fix a slightly very stupid mistake that I've made.

I'm trying to recreate the conductive lines of a membrane keyboard, unfortunately after trying to unglue them they got ripped off, I've painted 2 coats but it I'm receiving no signs of life from it.

Is Liquidwire the wrong paint for the job? Maybe the circuit lines ar too long to fix? Should I try copper or silver paint?

I've read online that shaking the pain is not enough and that I should also stirr it.

I have two led strips used for 2x27" monitor bias lighting. Each have their own USB cables for power. These two USB cables are plugged into a 2-port wall charger for a phone. I would like to use a 2x female to 1x male adapter to join the two USB cables into one, then plug it into a much smaller 1-port USB wall charger. The reason is due to my space constraints.

Will doing this impact its energy efficiency, ie using an adapter like this?

https://www.aliexpress.com/item/1005004340044483.html

Hi, I have built a microvawe transformer spotwelder, I have put a single turn of welder wire for in the secondary and I'm timing it with arduino. Worth mentioning it was/is a 230V transformer. Electrodes are sharpened copper rods. I believe the voltage is still high. The spotwelds it produces are slightly discolored and not as strong as you would expect. Is this design fundamentally borked? Is there anything else I can make to make it better? Photo from test stage before it was built into a project box, it is less "shocking" now.

Currently, only one company in the world -- ASML -- has the technological capability necessary for the creation of photolithography machines which are sufficient for the production of modern semiconductor devices. What I'm wondering is at what point does semiconductor manufacturing become practical, or even feesible for small organizations, or independents? One must be able to surpass the cost of the machines, and the resources necessary to manufacture them. I presume that a company like ASML is also extremely picky -- willfully, or by regulation, or otherwise -- about who they lend their technology to.

I'm not sure if this is the right community for this sort of post. Please let me know if not, and if there is a more suitable place to put it.

Hi!

I've asked Siglent support but after a couple of responses the thread went cold. Maybe I'm being dumb but I've noticed that there's a frequency (low, around 100Hz) where scope response changes a bit. Below and above it square input looks square. Right about it square input looks slanted.

I tried to do a very slow "sweep" and there's small but visible change in the envelope. So, e.g. with a constant 600mV p2p input lower frequencies measure exactly that while higher ones measure 612mV, so ~2% diff.

Terminated 50Ohm cables (not that it matters at such a low freq) to be sure. Latest firmware, after full self-cal. Siggen itself seems allright, I have an ancient Tek scope and the siggen output looks Ok there with same input/same cables. Scope seems happy and fully functional otherwise, few years old though, out of warranty.

Has anyone else seen anything like that? Is this a normal behavior within the expected margin of error?

Thanks!