Quote:
Originally Posted by gold24h
I was just curious if a scientific calculater like on the rangertell could actually be emitting radio waves,in fact it does,i found an fcc warning on a hewett packard scientific calculater,it said this device emitts raido waves but below the limit allowed,it also said it could interfere with tv and othere raido,so there may really be something to this rangertell.Also i found a chat on a forum about taking a calculater and an am radio and making a metal detecter,supposably the calculater sends out signals that the radio picks up.
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Quote:
Originally Posted by gold24h
Over on "that other LRL forum", arguments occasionally break out over whether pocket calculators radiate energy, and if so, how far. I usually stay out of that one because yes they do radiate energy, and "how far" depends on what kind of radio receiving apparatus you've got. All of that misses the point of course: if you swap the calculator for a CB radio with 1 watt output capable of being received at 10 miles with an ordinary receiver, that wouldn't make it any better a "treasure finder" than gluing a dried toad to the swivelly thingy instead.
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Hi gold24h and Dave,
Yes the calculator found on the Examiner does send out radio waves. These radio waves originate because the calculator has an internal clock which operates in the audio range usually below a few kilohertz as the highest clock divider. But the rising and falling edges of the clock signal can emit a small amount of noise at higher frequencies which are usually seen as random switching noise, and can be detected as broadband noise by nearby radio receivers or other sensitive electronic instruments. Dave is correct, it depends on what kind of receiving apparatus you have. Usually, radio receivers are designed to reject random noise, but at close distance, we see cheap radios are not immune. However, if you were to use a receiver that was designed to tune a known range of noise that comes from a calculator, you should be able to find a greater range than with a cheap pocket radio.
If you are planning to build a metal detector using a calculator and a pocket radio, then the range is limited by the ability of nearby metals to change the reception of this broadband noise. This has been seen to be about 2-5 inches in the examples that I have observed. If you wanted to make a metal detector with this concept, you may be better to build a small digital clock type oscillator that runs at a few KHz on a 9v battery. The voltage is important for producing longer range in broadband noise.
When you have apparatus that is not capable of tuning RF, then the distance which you can detect the noise from a calculator is much less. I did some test measurements on the calculators that come with an Examiner to see how far the calculator signals can be detected with a non-tuning pickup for magnetic and electric fields. I found that there is very little magnetic field detectable from calculator clocking noise, but the electric field can be detected up to about 6 inches distance before it becomes too weak to detect from among the background noise that is in the air. When you test the Examiner calculator using the same kind of spiral coil placed in the same position as the Examiner uses, you will find the signal strength shows about 1-2 mV on an oscilloscope for the higher clock frequencies, and it becomes smaller as you move the pickup coil farther away from the calculator. The larger voltages can be as high as 10mV, which are almost always lower frequencies which are envelopes that begin a pulse train to scan the keyboard.
I actually did a study on two different Examiner calculators. One was powered by two cells at 3v, while the other deluxe model used a TI solar calculator. It was surprising to see the deluxe solar calculator model produced a noticeably weaker signal, because it can only reach about 1.8v in the brightest sun. Even stranger, the clocking frequency is very much dependent on the brightness of the light that falls on the calculator. I watched the clocking frequency drop from 285 Hz in bright sun to 84 Hz in dark shady areas. During most sunny days it ran between 200-260Hz.
How any of this helps to find treasure, I haven't been able to figure out. In fact, I haven't seen anyone find treasure with an Examiner.
I have already posted a report showing some tests I ran on the earlier Examiner model T-G 808B here:
http://www.longrangelocators.com/for...7393#post11739
And now I am posting some additional testing I did for the Deluxe model with the TI solar calculator.
The solar calculator testing is much more revealing, and it shows some peculiar measurements that were not expected from these calculators or from the Examiner internal circuits.
See the ZIP files under the picture below. When you unzip the files, click on the html file to see the reports.
Best wishes, J_P