Crude Radiated EMI Meter

[D from BC]

Sometime in the 90's, one of my hobby ideas was to make an amplifier
so sensitive that it would detect the faint radiated EMI from
electronic equipment.
It used low noise transistors and active filtering to form a 300Hz
high pass high gain amplifier.
I recall seeing on the scope the EMI from my LCD watch 2" away from
the pick up coil.

I couldn't think of an application then and still can't now.
Would such a crude gizmo have any application today?
Guesses:
Electronic device detector? Bug sweeper.
Data cable is alive detector?
EMI meter for the EMI paranoid?
Audiophool interference source detector?
D from BC

 

[Robert Baer]

Sometime in the 90's, one of my hobby ideas was to make an amplifier
so sensitive that it would detect the faint radiated EMI from
electronic equipment.
It used low noise transistors and active filtering to form a 300Hz
high pass high gain amplifier.
I recall seeing on the scope the EMI from my LCD watch 2" away from
the pick up coil.

I couldn't think of an application then and still can't now.
Would such a crude gizmo have any application today?
Guesses:
Electronic device detector? Bug sweeper.
Data cable is alive detector?
EMI meter for the EMI paranoid?
Audiophool interference source detector?
D from BC

Absolutely audiophool product if nothing else!

 

[[email protected]]

Sometime in the 90's, one of my hobby ideas was to make an amplifier
so sensitive that it would detect the faint radiated EMI from
electronic equipment.
It used low noise transistors and active filtering to form a 300Hz
high pass high gain amplifier.
I recall seeing on the scope the EMI from my LCD watch 2" away from
the pick up coil.

I couldn't think of an application then and still can't now.
Would such a crude gizmo have any application today?
Guesses:
Electronic device detector? Bug sweeper.
Data cable is alive detector?
EMI meter for the EMI paranoid?
Audiophool interference source detector?
D from BC

Such tools are common accesories in TDR kits, and are used to locate
breaks in coax. You do the rough location with the TDR, then inject a
signal at one end of the coax and wave the detector along the cable
where the TDR tells you to look. When it responds, you've found the
break.


Mark L. Fergerson

 

[DaveM]

Such tools are common accesories in TDR kits, and are used to locate
breaks in coax. You do the rough location with the TDR, then inject a
signal at one end of the coax and wave the detector along the cable
where the TDR tells you to look. When it responds, you've found the
break.


Mark L. Fergerson

Care to share the schematic on abse??? I sometimes work with flea power
systems; something like that might be helpful.

Thanks,
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Some days you're the dog, some days the hydrant.

 

[[email protected]]

Care to share the schematic on abse??? I sometimes work with flea power
systems; something like that might be helpful.

I can't share the ones I'm familiar with, which are the intellectual
property of the company I worked for that made them. The OP might
share his though.

Besides, I use Google groups which doesn't access binary groups.
Dammit.


Mark L. Fergerson

 

[D from BC]

Care to share the schematic on abse??? I sometimes work with flea power
systems; something like that might be helpful.

Thanks,

That's was a long time ago.. It was a napkin to breadboard project.
The napkin is gone and the details are fuzzy now.. I recall a bit.

There was multiple stages of single transistor amplifiers.
Maybe 4-6 stages..
I can't recall if I used JFET or bipolar. I had feedback between
stages for active filtering.
I used a battery to power everything.

I may have tried an amplifier array with summing amplifiers.. All done
with single transistors. Something to do with the way noise adds
together resulting in less noise.

D from BC

 

[[email protected]]

Sometime in the 90's, one of my hobby ideas was to make an amplifier
so sensitive that it would detect the faint radiated EMI from
electronic equipment.
It used low noise transistors and active filtering to form a 300Hz
high pass high gain amplifier.
I recall seeing on the scope the EMI from my LCD watch 2" away from
the pick up coil.

I couldn't think of an application then and still can't now.
Would such a crude gizmo have any application today?
Guesses:
Electronic device detector? Bug sweeper.
Data cable is alive detector?
EMI meter for the EMI paranoid?
Audiophool interference source detector?
D from BC

http://www.zapchecker.com/
Works well. It uses an ADI chip.

 

[D from BC]

http://www.zapchecker.com/
Works well. It uses an ADI chip.

Wow...So that's the way it could have turned out if I went all the
way...
I dropped this idea long ago and then to see somebody else complete
the same idea...
It's like it's accomplished but without all the hard work

Thanks..
D from BC

 

[[email protected]]

Wow...So that's the way it could have turned out if I went all the
way...
I dropped this idea long ago and then to see somebody else complete
the same idea...
It's like it's accomplished but without all the hard work

Thanks..
D from BC

Alan Broadband is quite the garage shop as far as I can tell. The
owner sold these boxes for a few years at ham fleamarkets for I think
$80. I've used it when trying to improve shielding in radios and
SMPS. You can get relative readings regarding improvements, not
calibrated of course. This box is considerably more sophisticated than
your initial design. It has response out to a few GHz, yet can send
power lines (probably harmonics of 60Hz). It has a vibrator in it to
go off when RF is sensed, but the implementation (at least in the
original product) is kind of dumb. The vibration changes with
strength, but it's hard to sense this. I would have rather had it just
turn on once the RF level reached a certain point. It also has a LED
so that you can sense very short bursts of RF that won't move the
meter. I've used this to detect when radar is active.

Note the biggest expensive in the design is the plastic case. Anything
that needs to be tooled is a big hurdle to goring from garage shop to
real sales.

 

[Joerg]

Wow...So that's the way it could have turned out if I went all the
way...
I dropped this idea long ago and then to see somebody else complete
the same idea...
It's like it's accomplished but without all the hard work

It can be worse. Once in an ultrasound company we held a brainstrom, to
see which other products could possibly be designed and built there. Me
and a few others stuck our heads together and came up with a sonic
toothbrush. Upon presenting it we harvested thundering laughter, people
almost rolling on the floor.

Fast forward a decade or so: Philips makes oodles and oodles of money
with that very product, a sonic toothbrush. We've got them in our
bathroom. They work!

 

[Joel Kolstad]

Fast forward a decade or so: Philips makes oodles and oodles of money with
that very product, a sonic toothbrush. We've got them in our bathroom. They
work!

I have an Oral-B Triumph, which has a universal input (switching) power
supply, a ~64x32 LCD, and even some sort of RFID-like ability to identify
which brush head you're using. Pretty fancy stuff... although it's not sonic.

 

[Joerg]

I have an Oral-B Triumph, which has a universal input (switching) power
supply, a ~64x32 LCD, and even some sort of RFID-like ability to identify
which brush head you're using. Pretty fancy stuff... although it's not sonic.

Wow. Pretty soon they'll come with Bluetooth and when the kid gets lazy
a large sign will light up outside the bathroom: "Did not brush teeth!"
Or an automated message goes out to the dentist scheduling the
inspection or cleaning visit.

We've got Philips Sonicare. Works fine.

 

[D from BC]

Wow. Pretty soon they'll come with Bluetooth and when the kid gets lazy
a large sign will light up outside the bathroom: "Did not brush teeth!"
Or an automated message goes out to the dentist scheduling the
inspection or cleaning visit.

We've got Philips Sonicare. Works fine.

Waiting to see episode of Doctor Who where he uses his sonic
screwdriver on his teeth..
Or the XXX version where he's using it on alien women.....

New invention: The Swiss Army Cell phone
Cell phone + camera + bluetooth + palm + mp3 player + games + movies +
sonic tooth brush + scissors + saw + screwdrivers + paint mixer +
laser pointer + fork + DMM + lint remover + toe nail clipper.....

It'll bring back McGyver!!
D from BC

 

[Michael A. Terrell]

Waiting to see episode of Doctor Who where he uses his sonic
screwdriver on his teeth..
Or the XXX version where he's using it on alien women.....

New invention: The Swiss Army Cell phone
Cell phone + camera + bluetooth + palm + mp3 player + games + movies +
sonic tooth brush + scissors + saw + screwdrivers + paint mixer +
laser pointer + fork + DMM + lint remover + toe nail clipper.....

It'll bring back McGyver!!
D from BC

You'd need him to help carry it.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[D from BC]

On Fri, 02 Feb 2007 08:25:39 GMT, "Michael A. Terrell"

You'd need him to help carry it.

lol ...good one...
D from BC

 

[krw]

It can be worse. Once in an ultrasound company we held a brainstrom, to
see which other products could possibly be designed and built there. Me
and a few others stuck our heads together and came up with a sonic
toothbrush. Upon presenting it we harvested thundering laughter, people
almost rolling on the floor.

Fast forward a decade or so: Philips makes oodles and oodles of money
with that very product, a sonic toothbrush. We've got them in our
bathroom. They work!

When was this? My dentist had a sonic cleaner 30ish years ago. It
didn't seem to be a huge leap to take it from the doctor's office
into the bathroom.

 

[Joerg]

When was this? My dentist had a sonic cleaner 30ish years ago. It
didn't seem to be a huge leap to take it from the doctor's office
into the bathroom.

In 1988 AFAIR. Sure, this wasn't anything patentable but back in those
days only dentists had that. Very expensive, too. The brainstorm was
about what we could design and build, not invent ;-)

What we did build was another neat thing: A "Pocket Doppler". It was a
sort of pen-like device and given away to key account medical offices.
Much cheaper than the typical large table-top units. Very handy in an
emergency, like when you had to quickly ascertain whether there was
enough blood flow in the femoralis and whether the Doppler sound was
suspicious. There were guys who could listen and say "that sure sounds
like a valve problem". Sent them right to the catheter lab. And sure
enough the angiogram pointed in the same direction.