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54 votes

Cheap and safe way to dim 100+ 60W Incandescent bulbs

Mains guy here. Nothing in LV electronics prepares you for mains. Don't be cheap Doing anything with mains electrical plays rather badly with "cheap". Or should I say "inexperienced people ...
36 votes
Accepted

What went wrong with my DIY project?

Congratulations on spending time and effort with your son learning the practical aspects of electronics. [Be aware that this may have the effect of turning him into an engineer :-) :-) ]. It is ...
  • 144k
20 votes

Film/TV question: How to build Foam Cutter from only household items

"Cut the foam! Cut the foam!", she cried as she wriggled and squirmed in the styrofoam dishwasher packaging she got stuck in. "With what?", cried Bob as he scanned the kitchen for something suitable. ...
  • 163k
16 votes
Accepted

What is "switched neutral"?

General appliance wiring looks like this: This is "switched Live" and is the preferred way to do it because once you switch it off, the appliance is not connected to high voltage. It's safe ...
  • 7,596
15 votes

What went wrong with my DIY project?

Those two joints look like they were cold soldered to me - the parts moved before the solder had cooled completely. So, bad connection to the circuit. At the same time, there's a little splatter of ...
  • 61k
15 votes

What went wrong with my DIY project?

The plastic connector is backwards. The one in the lower right has notches on the board that match up with the notches on the connector. These are keyes that prevent plugging the wrong way around.
15 votes

Creating lung ventilation to fight COVID-19

I suppose it should be not very difficult to create DIY lung ventilation project Um, and what experience in the field of human ventilation engineering gives you that supposition? Seriously, this is ...
14 votes

DIY battery from scratch. Is it possible?

Any battery you buy is going to be far cheaper than one you build. Those folks who make them for a living have a lot of know-how, experience, machinery to make them, techniques to get large surface ...
  • 145k
13 votes

How to get 20 V from a USB-C charger?

In a word, no. You need to implement the USB Power Delivery protocol through the CC line of the Type-C connector and that's a two way communication at 300kbps complete with preamble, CRC and so on ...
  • 5,338
12 votes

How this DIY High-Speed Probe doesn't reflect signals?

The point of this probe is that the scope has its 50Ω termination enabled. Since the scope input impedance is matched to the cable, there is no reflection from the scope. Once the load side is matched,...
  • 2,458
9 votes
Accepted

UV solder mask sticking to cover instead of PCB

Happy times, problem solved: The issue was not, as helpfully suggested by @Sachin in the comments, the UV (lamp vs sun), age of material (> 1 year), duration of initial curing, but, also put forth by ...
  • 492
9 votes

SMD transistor die vs DIP transistor die

Assuming you're asking about the die, then parts with the same part number from the same manufacturer will typically have identical dice inside regardless of what package they use. There's no rule ...
  • 21.3k
9 votes

Cheap and safe way to dim 100+ 60W Incandescent bulbs

You should try wiring one of the fixtures as 2S2P. I'm betting that this will give you the nice warm glow you're looking for, and it's the easiest thing to implement.
  • 165k
8 votes
Accepted

Mains LED light bulb flickers when switched off

You might find that a different brand of bulb is much less prone to this kind of behavior. The internal circuit varies quite a bit from bulb to bulb. If you have a store with a generous return policy ...
8 votes

series charging three 18650 batteries with three chargers off the same 5V supply

No, this won't work. You can't simply daisy chain chargers but drive them off the same 5V supply. Your charger needs to be able to define both the out+ and out- rails (chances are, out- is directly ...
8 votes

Cheap and safe way to dim 100+ 60W Incandescent bulbs

One time event? 25 fixtures? For this do hire companies exist! While series strings and such are possible, the elephant in the room is most likely power distribution, specifically all that cable (...
  • 16.2k
8 votes

What is "switched neutral"?

It's a switch in the neutral wire, instead of the hot/live/phase wire. It is generally considered to be a bad thing, as turning the switch off turns off the appliance, but there is still a live feed ...
  • 15.6k
8 votes

Matching number of LEDs to power supply

According to the datasheet, the LED's Vf is 3.05V @ 1500mA, which is close enough to the 1400mA constant current provided by your power supply. The power supply's maximum output voltage is 69V. 69V / ...
  • 4,124
7 votes

Mains LED light bulb flickers when switched off

The cause of this is the design of the electronics inside the bulb combined with stray capacitance between live and switched live. In the UK it is most commonly seen on 2-way switching installations ...
  • 19.8k
7 votes
Accepted

What are an amateur's options to put a high-end IC on a board?

What's your budget? You can always breadboard using breakout boards as mentioned in another answer, but you'd maybe get half of those 24 ADC bits as useful information that way. Getting even 16 useful ...
  • 795
7 votes
Accepted

Techniques for building 'Bed of Nails' testing board

Having the board artwork helps, but if you don't, you can use a sacrificial blank PCB as your template. Fix the blank PCB the appropriate way up, usually bottom side up, to your bed of nails ...
  • 45.9k
7 votes
Accepted

Can't make simple oscillator based on NE555

You've got the polarities on your power supply swapped. The positive outputs of the PCB connect to the negative (blue) power strips on your breadboard and vice versa. There's a chance you damaged your ...
  • 4,124
7 votes

How to measure voltage of a system with a different GND reference?

Measure the voltage of '?', and the voltage of GNDD, simultaneously, then subtract. A way to do this with one channel rather than two is to measure the difference between ? and GNDD with a ...
  • 145k
6 votes
Accepted

Would it be possible to make a solid state transistor by hand?

Well, yes and no. You can make a transistor by hand in your kitchen. It will involve some nasty chemicals, but it is doable. A friend of mine made a LED a couple of years ago. Not a transistor, sure,...
6 votes
Accepted

Safety when using ATX power supply as benchtop supply

It's quite far from certain death (indeed, it's voltages "generally recognized as unlikely to be hazardous", but we just had a big long discussion of that starting from a more hazardous and less ...
  • 5,544
6 votes
Accepted

Most efficient way to power a 5 V circuit from a 14.8 V battery

There are dozens of small, inexpensive DC-DC converters available on Ebay, Amazon, etc. They are based on industry-standard converter chips and are quite convenient to use. You can find versions with ...
6 votes

Is there way to construct an 18650 battery pack with built-in balance charging? Or is balancing not very necessary?

I think you mis-interpret how your BMS balances cells during charging. For a 3 cell BMS, there are typically FETs across each cell. When a cell is getting close to fully charged, the FET is used to ...
  • 21.2k
6 votes

Problems trying to wire a USB-C cable

There are two types of Type-C to Type-A cables, one is Type-C to Type-A plug, and another is Type-C to Type-A receptacle. The cables play two different roles, and must be built differently. The Type-...
  • 37.7k

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