Crude Radiated EMI Meter

Absolutely audiophool product if nothing else!

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,

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

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

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.

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!

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.

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..... :P

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

sonic.

You'd need him to help carry it.

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

lol ...good one... :) D from BC

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.