Show HN: Capacitor Alarm Clock

The actual "make it go bang" bit here isn't the most potent. (I think I have capacitors here which wouldn't care in the least about this, despite their datasheet ratings.)

If you need to take it to the next level, consider something based on a xenon photoflash driver. These aren't as common as they used to be, but they're still not hard to make. I had to make one of these a while back and ended up using one of those $5 LTC chips but that was appropriate for the situation; there are certainly other ways to do it. This will basically charge a 400V capacitor up for you, which you can then dump into the 5V part. High-quality 5V capacitors will handle small spikes of this. But using a big 400V capacitor will make a big spike, which is not kind to the other capacitor. (I must confess I didn't try blowing up a lot of things on the one I made, but it was medical test gear, not technically a capacitor-blower-uper, and I was on deadline anyway. I also had other, significantly more destructive, equipment available to me should that be the goal.)

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'?]"

I expected an alarm clock using a capacitor for timing. Either charge it to a delay-dependent level, or charge it to a fixed level and discharge through a delay-dependent path, or trigger when it drops below a delay-dependent level.

There are some grades of electrolytic capacitors for which this is probably the only thing they should be used for.

Heh. I hoped to see a fully analog capacitor-based "movement", either a mechanical movement powered by periodic electric pulses, or maybe a device using split-flap displays powered by three highly precise, thermally-compensated capacitor discharge circuits.

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!!!!

That sounds completely safe and healthy! Hmmmm, I love the smell of vaporized electrolyte, particularly when waking up!

There's a video demonstration about halfway down the GitHub

https://github.com/ArcaEge/capacitor-alarm-clock#Demo

The perfect alarm clock would start lighting your life dreams on fire if you didn't wake up, cause that's whats happening anyway.

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...

Electroboom did this first, right?

Is this not technically an IED?

What’s happening at the electron level that makes them do this? Anyone know?

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.

the alarm clock for the ai age, it needs an LLM

How about a flux capacitor clock?

that's a bomb dude.. lmao.. don't take that anywhere!

gng thats crazy!