Show HN: Capacitor Alarm Clock
github.comI made an alarm clock that blows up capacitors to wake you up.
There are more details on the Github repo but it's made from an esp32-c3 as the microcontroller, with 3 capacitor slots. There are relays on each capacitor slot to put 15v reverse voltage on the capacitor, with 5.1 ohm resistors on each slot for current limiting in case the capacitor shorts out. I also chucked in an SSD1315 OLED to show the time and a menu to configure it, although there's a web UI as well. The esp32 also means you can fetch the time from NTP.
It also functions as a small heater since I used LDOs to step down 15v to 3.3v for the esp32, I was lazy and didn't use a buck converter circuit :) This reminded me of a Blog entry I wrote about in 2013 on "Massive Electro-Pyrotechnic Initiator Chip Resistor (MEPIC)". These are 0805 chip resisters that are by design meant to let out the Magic Smoke that runs all electronic parts. Sadly I could not get free samples from my Vishay Rep, that I was in good standing with. MEPIC85N8R0KTT come in lots of 10,000 to buy. Be sure to check out the application note "A Guide to Using EPIC / MEPIC Igniters in Pyrotechnic Applications". https://www.vishay.com/en/product/53058/ National Semiconductor, bought by TI, used to make a similar part, check out the application note: https://www.ti.com/lit/an/snoa217/snoa217.pdf This is what I wrote about the MEPIC parts a long time ago: "MEPIC resistors, also known as bridge resistors, are resistive elements that convert electrical energy into heat energy in a precise electro-thermal profile for the purpose of initiating a series of pyrotechnic events in a controlled energetic reaction. [They go BOOM on command, which is different than Rapid Spontaneous Self-Disassembly.] The new Vishay Sfernice resistor is optimized for electronic igniter applications in automotive safety systems for the deployment of airbags and other safety devices; digital blasting in mining applications; and in fireworks applications for better synchronization of fireworks, music, and special effects. With firing energy down to 1.5 mJ and a typical ohmic range of 2 Ohms (+/- 10 %), the device provides designers with very predictable, reproducible, and reliable behavior. Offered in the standard 0805 case size for the wraparound and flip chip versions, with other sizes available upon request, the resistor features easy set-up of firing levels, and is compatible with various pyrotechnic compositions. Offering ESD withstanding to 25 kV without extra protection, the MEPIC resistor's performance meets no fire/all fire conditions and the requirements of USCAR, AKLV16, and major car manufacturer standards. The device is RoHS-compliant and conforms to Vishay "Green" standards. [Is it not great that Fuzes are 'Green'?]" Nice job OP, and thanks for the demo video! PS to others, keep your volume below 40%. ...I may or may not have jumpscared myself by cranking the volume up before the alarm time as it was so quiet. Sorry I'm late, the capacitor didn't blow. Did anyone else smell capacitors when they watched the video? The brain does funny things. Based. Unhinged. Don't try this at home. But it is also art. It represents the waste in our devices that play out over 1-4 years (or say a few weeks for a vape) but in one night. But yeah. Don't do it. Indoors? wtf!!!! Oh no. I quite liked this until you said it was art that Represented something. To be brutally honest it sounds like LLM speak to me. The account being in green doesn't help. The line between an LLM being told to sound like an HN user, and an actual user who's adopted LLM lingo is... vanishingly thin at times. I myself accidentally find myself using such phrases, I can hardly accuse others. I am human, to prove it I have laid down an em-dash below: — The perfect alarm clock would start lighting your life dreams on fire if you didn't wake up, cause that's whats happening anyway. That sounds completely safe and healthy! Hmmmm, I love the smell of vaporized electrolyte, particularly when waking up! I feel like a wire detonator would be safer plus the consumables would be cheaper however even then I doubt vaporized copper or aluminum is good for you. Honestly just roll some firecrackers and use the ESP to light them off. For some reference work https://www.youtube.com/watch?v=agwKNLoU6g8 There's a video demonstration about halfway down the GitHub Electroboom did this first, right? The README references Electroboom's implementation So it’s not UL listed? Do you need the 15V input to torch the capacitors and run the relays?
Could I use a 5V USB ESP32 dev board instead, and just put a boost circuit or MOSFET on the relay load side for the explosion circuit when it needs to go off, or are there other components that need the higher voltage? Try this with a tantalum capacitor. Careful not to lose an eye... Luckily our eyes tend to be closed when we're asleep. Evolutionary safety squints. Is this not technically an IED? Doesn't look improvised to me. What’s happening at the electron level that makes them do this? Anyone know? If I recall correctly, electrolytic capacitors have to get "burned in" during manufacturing to make them work. A current is passed through the capacitor and a thin film of oxide is built up in one of the terminals, according to the polarity. This is why electrolytic caps have polarity, if you use them with their polarity inverted, you flake off that oxide layer and thus short them out. A free running current in that electrolyte boils it off, and you get an exploding cap the alarm clock for the ai age, it needs an LLM It is an LLM a Life limiting machine How about a flux capacitor clock? that's a bomb dude.. lmao.. don't take that anywhere! gng thats crazy!