Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A Beginner's Two-Component Crystal-Style Wi-Fi Detector

siliconjunction.wordpress.com

Post reply on HN
Print view View original

41–45 of 45 posts

Re: A Beginner's Two-Component Crystal-Style Wi-Fi Detector

#41

Post by macintux »

jeffbee wrote: post #37
zxexz wrote: post #3

Earlier quoted context omitted.

Sounds like he’s in need of a new microwave. Not tongue-in-cheek; sounds like there’s something up with the shielding, and if it’s not visible, how will you know if it gets worse? Edit: I see no reason this wouldn’t work, however?

There is not substantial variance from one microwave to the next. They are all made by one outfit, then dressed up in different superficial brands and priced randomly. The emissions of a microwave oven are regulated by the FDA, not the FCC.

That doesn't mean, however, that an aging appliance can't misbehave.

Re: A Beginner's Two-Component Crystal-Style Wi-Fi Detector

#42

Post by thenthenthen »

ides_dev wrote: post #28
thenthenthen wrote: post #20

I made hundreds of these. Never worked

Hundreds? Really? I can see making two or three before giving up, but to build hundreds..

I never give up. Tried soo many different diodes, but the ‘good’ ones seem very susceptible to clones/fakes since they arent manufactured anymore. There is a company that makes dedicated IC’s that can harvest the emf very efficiently, bit expensive though… and a black box..

Re: A Beginner's Two-Component Crystal-Style Wi-Fi Detector

#43

Post by peter_d_sherman »

>"Using just two components — a

high-speed [1N5711] Schottky diode

and an LED — you can build a tiny “crystal detector” that responds to

2.4 GHz

Wi-Fi, Bluetooth, and even microwave..."

That is interesting!

I never knew that a Schottky diode could rectify at 2.4 GHz -- that's pretty darn impressive!

Re: A Beginner's Two-Component Crystal-Style Wi-Fi Detector

#44

Post by pseudohadamard »

jqpabc123 wrote: post #2

Can this be used to detect radiation escaping a microwave oven? A friend of mine has a microwave that noticeably degrades his wifi when it is in use.

If they're seriously concerned, you can get microwave leak detectors for very little money from most crapvendors. The problem with this design is that while it's a cool toy it'll be prone to false negatives...

Re: A Beginner's Two-Component Crystal-Style Wi-Fi Detector

#45

Post by shibapuppie »

avidiax wrote: post #9
bgbntty2 wrote: post #4

Earlier quoted context omitted.

I've tested a few microwaves from different manufacturers with my phone a few years ago. I think I looked at some file in my router (OpenWRT), but I can't recall. I got a lot of dropped packets each time. The amount of degradation was similar for the different microwaves. I had to put the phone close to the microwave to detect this. The degradation was obviously stronger when the phone was closer. If your friend expe…

> If your friend experiences noticeable degradation regardless of the distance within the room, it might be worrisome. Probably not. I recall calculating it once, and the legal requirements for microwave oven shielding still allow it to produce a few watts of 2.4Ghz leakage. This is contrasted to 50mW typical WiFi AP power, and 5-50mW BlueTooth powers. A few watts is totally non-dangerous to humans, especially diffus…

An old Unifi disc AP will do 100mw or 20dbm out of the box, a few cheap Cudy APs I have do about 400mw or about 26dbm.

On 2.4 GHz in the US you're allowed up to 36dbm, 30 of that can be transmitter, the remaining 6 can be a higher gain antenna.

Post reply on HN