LoadsOfTime
Posts: 23
Joined: Sun Oct 15, 2017 5:48 am

Detecting microwaves

Fri Sep 10, 2021 2:05 am

I would like to know if my microwave is leaking, is there anything I could use to detect that please ?

aBUGSworstnightmare
Posts: 3627
Joined: Tue Jun 30, 2015 1:35 pm

Re: Detecting microwaves

Fri Sep 10, 2021 5:36 am

Use google to search for microwave leakage detectors. A Pi can't do this on it's own.

drgeoff
Posts: 12240
Joined: Wed Jan 25, 2012 6:39 pm

Re: Detecting microwaves

Fri Sep 10, 2021 7:46 am

There are no electrical or electronic components in the oven whose failure would cause it to leak. It is the physical integrity which matters. All internal and external covers in place and the door closing correctly. The door glass incorporates a perforated metal shield. No food residue or other build-up should be between the mating surfaces of door and casing.

Most common cause of leaking is distortion of the door/casing/hinge caused by dropping the oven and resulting in gap between closed door and casing.

There are dedicated hand held detectors. No battery required. They have an internal aerial, rectify whatever 2.4 GHz is picked up and feed to a moving coil meter indicator. https://www.amazon.co.uk/Faithfull-DETM ... B00CD2942S
Quis custodiet ipsos custodes?

ganzgustav22
Posts: 253
Joined: Tue Feb 11, 2020 1:04 pm

Re: Detecting microwaves

Fri Sep 10, 2021 9:35 am

A few years ago I was testing a wifi transmission at very low signal levels and I could actually tell when my neighbour next door was using his microwave. At first I wondered what is causing the sudden packetloss from time to time, lasting about 2-5 minutes. Then, someday, when we both had our windows open, I realized that the packetloss always stopped exactly when I heard that "ping" sound from his kitchen ...

LoadsOfTime
Posts: 23
Joined: Sun Oct 15, 2017 5:48 am

Re: Detecting microwaves

Fri Sep 10, 2021 7:37 pm

Thanks for the info guys.

I never thought that there would be a battery free option. The reviews seems steady too.

I wonder, when checking a microwave, will meter readings be interfered with from a WiFi router, should I switch it off while performing a check, or does detection require point blank access, do microwaves dissipate into the atmosphere I wonder, and at what distance ?

Interesting story about your neighbour !

emma1997
Posts: 1656
Joined: Sun Nov 08, 2015 7:00 pm
Location: New England (not that old one)

Re: Detecting microwaves

Fri Sep 10, 2021 8:38 pm

No need to turn off router unless it is right next to the oven. Because RF is square law and not linear you have to be real close to the source to get any reading (unless it's megawatts).

Actually all you need is a few inches of wire, diode, resistor, and penny cap. I've not done this with Pi but did many times with AVR chip which is not as sensitive as Pi. It could detect the 2.4g even though there was no problem with oven leakage. Also noticed small slowdown in router when nuking supper too.

Same circuit could detect FM radio broadcast even though station was many miles away but we are talking megawatts here.

drgeoff
Posts: 12240
Joined: Wed Jan 25, 2012 6:39 pm

Re: Detecting microwaves

Fri Sep 10, 2021 9:59 pm

LoadsOfTime wrote:
Fri Sep 10, 2021 7:37 pm
Thanks for the info guys.

I never thought that there would be a battery free option. The reviews seems steady too.

I wonder, when checking a microwave, will meter readings be interfered with from a WiFi router, should I switch it off while performing a check, or does detection require point blank access, do microwaves dissipate into the atmosphere I wonder, and at what distance ?

Interesting story about your neighbour !
Microwave ovens use the same frequency band as 2.GHz Wi-Fi so the radiation from them suffers loss the same as Wi-Fi does.

The power levels are vastly different. A typical home Wi-Fi router might take an Ampere or two at 12 Volts but most of that is converted to heat so the RF power emitted is only tens or a few hundred milliwatts. The magnetron in a microwave oven is pumping out hundreds of Watts. It doesn't boil a cup of water in less than a minute by magic - still needs the same energy going into the water as an electric kettle would use. That's why you only need a small percentage leakage to affect WI-Fi. Yes they do leak some but if only a low level it is no more dangerous than a Wi-Fi router.
Quis custodiet ipsos custodes?

W. H. Heydt
Posts: 15115
Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: Detecting microwaves

Sat Sep 11, 2021 1:25 am

emma1997 wrote:
Fri Sep 10, 2021 8:38 pm
Same circuit could detect FM radio broadcast even though station was many miles away but we are talking megawatts here.
Unlikely. If I'm not mistaken, radio stations in the US are limited to 50KW. Hence locating XTRA in Mexico and broadcasting with 500KW.

ame
Posts: 3735
Joined: Sat Aug 18, 2012 1:21 am
Location: New Zealand

Re: Detecting microwaves

Sat Sep 11, 2021 1:48 am

I just wear a tinfoil hat. Keeps me safe from microwave leakage and 5G emissions.

Heater
Posts: 18649
Joined: Tue Jul 17, 2012 3:02 pm

Re: Detecting microwaves

Sat Sep 11, 2021 7:41 am

ame wrote:
Sat Sep 11, 2021 1:48 am
I just wear a tinfoil hat. Keeps me safe from microwave leakage and 5G emissions.
But, but...how do you know your tinfoil hat is not leaking?
Memory in C++ is a leaky abstraction .

jools72
Posts: 75
Joined: Sun Sep 29, 2019 12:40 pm

Re: Detecting microwaves

Sat Sep 11, 2021 9:07 am

ame wrote:
Sat Sep 11, 2021 1:48 am
I just wear a tinfoil hat. Keeps me safe from microwave leakage and 5G emissions.
But the tinfoil hat acts as a receptor and amplifies the waves, making it easier for the government to listen to your brain.

emma1997
Posts: 1656
Joined: Sun Nov 08, 2015 7:00 pm
Location: New England (not that old one)

Re: Detecting microwaves

Thu Sep 16, 2021 6:50 pm

W. H. Heydt wrote:
Sat Sep 11, 2021 1:25 am
emma1997 wrote:
Fri Sep 10, 2021 8:38 pm
Same circuit could detect FM radio broadcast even though station was many miles away but we are talking megawatts here.
Unlikely. If I'm not mistaken, radio stations in the US are limited to 50KW. Hence locating XTRA in Mexico and broadcasting with 500KW.
Yes, my comment was way off. Not sure but IIRC maybe the real limit is 100kw here in US with a few grandfathered significantly more? I should have known better because it was a question on the Extra Class test (maybe called Advanced back then?). Hope FCC don't get wind of my incompetence or they might just decide pull my ticket. lol

What's worser is the station I was referring to is actually only 9kw. Surprisingly not only enough for crystal radio as a kid but gets a reading on the DMM with the circuit I mentioned.

pidd
Posts: 2622
Joined: Fri May 29, 2020 8:29 pm
Location: Wirral, UK
Contact: Website

Re: Detecting microwaves

Fri Sep 17, 2021 8:53 am

Repair men that check your microwave for leakage are generally conning you, it takes a very obvious physical fault to the casing/door before a microwave leaks anything more than the extremely small amount of radiation that is normal.

To quote one of my friends who runs a domestic electrical repair shop - "I bought a microwave leakage detector twenty years ago, I have never found a microwave that leaks that I hadn't already condemned"

You don't need a meter, you just need eyes.

User avatar
davidcoton
Posts: 6544
Joined: Mon Sep 01, 2014 2:37 pm
Location: Cambridge, UK

Re: Detecting microwaves

Fri Sep 17, 2021 10:23 am

pidd wrote:
Fri Sep 17, 2021 8:53 am
Repair men that check your microwave for leakage are generally conning you, it takes a very obvious physical fault to the casing/door before a microwave leaks anything more than the extremely small amount of radiation that is normal.

To quote one of my friends who runs a domestic electrical repair shop - "I bought a microwave leakage detector twenty years ago, I have never found a microwave that leaks that I hadn't already condemned"

You don't need a meter, you just need eyes.
I have done some paid-for PAT testing for rental homes and other settings.
I have included a leakage test on microwave ovens, even though, IIRC, it is no longer required. (I've lost my 4th Edition Code of Practice, leakage tests were required in the 3rd edition.)
The quality of microwave sealing has improved over the years.
I have seldom found leakage -- but I have found a handful over the last 15 years.
Those that I found were older devices, but the faults were not visually obvious.
Location: 345th cell on the right of the 210th row of L2 cache

Return to “Off topic discussion”