Two ultrasonic articles - Page 3

J_Player · #51 05-25-2009, 02:54 AM

Quote:

Originally Posted by Fred

i think we are loosing contact with reality...your example above were not aplicable here,and i would not call this last one as a "distant" effect.
In relation to IR wavelenght , a few meters is gigantic.
Here is one other example,how a tranmiter can be afected by external conditions: monitor the power output of a transmiter, then change the medium where the antena is or make it close to a metalic object.The absorbed power (or SWR) will change. But that doesn´t work at long distance in relation to wavelenght.

My example above comparing a modified PI detector with Esteban's IR detector is very applicable. I am talking about the exact distance that Esteban described for IR LED experiments. According to Esteban, the distance is not very large, used for pinpointing only. This means reality for Esteban is the distance of PI metal detector range or slightly better. If we were to change to larger ranges, then this conversation would no longer be applicable, because Esteban did not find reality in detection with IR at long ranges of 10 meters for example, and was not limited to detection ranges of maybe 5 cm, for example. Esteban never said anything about measuring the SWR or changing the transmitting medium. What he said is the amplitude of a 400 Hz square wave transmit power signal is changed when the IR LED is pointed at a long time buried metal object. He said the IR LED does not have very long range. This is very much reality, exactly as Esteban described.

The comparison of a modified PI coil at the same reality distances as the IR LED that Esteban described will also show that the power traveling to the search coil will change when the coil is moved in the detectable range of the coil. (This PI search coil is at the same distance, or reasonably similar distance as the IR LED Esteban tested if you have a sensitive PI search coil).

Quote:

Originally Posted by Fred

Again,if you don´t have a receiver of some sort i can´t see any way to measure a diference in transmited power when pointing a beam of light to something distant.

As I previously suggested, and as Esteban confirmed, the IR transmitter is the receiver, just as many PI detector search coils are both the transmitter and receiver. It is not necessary to measure SWR, only to attach oscilloscope probes to the power leads of the PI coil and to the IR LED to see the transmitted waveform is changing for both of these detectors. You could also read my previous post to Max above, and build the simple circuitry I described to monitor the amplitude of the transmitted power. See here: http://www.geotech1.com/forums/showp...6&postcount=39
Esteban posted the information of how to do it, and I re-posted it in an easy to understand form. In fact, the dynamics inside the IR LED circuitry that Esteban described sounds strikingly similar to the dynamics inside a typical PI detector. All that is changed is the IR does not have a timing scheme to lock in on an expected counter emf signal from the target. He is only watching for a change in the overall power or average amplitude at the IR LED power leads. Apparently the property of a long time buried object that causes the transmit wave form to vary has not been identified, nor has circuitry been built to optimize the capture of the effect.

If I wanted to experiment with IR detection, I may choose a PI experimental project board such as Carl's hammerhead PI that allows a lot of adjustments to be made. This would give me the same square wave that is needed, but with adjustable widths, and lots of room for adjustable timing to look at any part of the pulse cycle from the rise to the fall and beyond. Perhaps this would be a good way to study how the IR reacts when different long time buried targets are in range.

The new example Esteban is now giving will confuse his earlier posts, because he is now talking about a different method of using a receiver rather than simply monitoring the transmitted power as he previously stated.

In his new example, Esteban is stating that the change in the transmitted power going into the single IR LED can also be detected by using a separate independent receiver to listen to the transmitted 400 Hz carrier sent by the transmitter. This is his way of monitoring the IR Tx power without connecting a probe to the wires inside or using the comparator circuit I earlier described. A small hand-held radio receiver can be converted for use in the field instead of carrying an oscilloscope or building a comparator and beeping section inside the IR LED detector.

Best wishes,
J_P

J_Player · #52 05-25-2009, 05:04 AM

For all who are interested in Esteban's methods of detecting long time buried metal objects:

Esteban's idea of detecting long time buried metal objects begins with what he calls "the phenomenon", sometimes called "halo" by others. The concept is that a long time buried metal object will be surrounded by soil that has different geotechnical properties than nearby soil without long time buried metal objects. The changed properties of this soil cause changes in secondary effects from existing natural and man-made energies that are found in the nearby vicinity. When all the changed properties of soil and associated secondary energies nearby are tabulated, there are many types of measurable effects from the long time buried metal object which constitute anomalies centered around the target. These anomalies are usually small in comparison to the surrounding energies, so sensitive instruments must be used to detect them.

Some of the larger anomalies that can be measured are:
1. Voltage anomaly in the soil around the long time buried metal object due to "ground battery" mechanisms from metal ions that have separated from the metal object and are combining with constituents in the soil.
2. Soil conductivity (or resistivity) anomaly in the soil, due to the presence of metal ions that have detached from the surface of the long time buried metal object and dissolved in the soil.
3. Anomaly in the space charge of the air above the long time buried metal object. This comes from the natural atmospheric leakage of current between the surface of the earth and the atmosphere. The theory is the air's charge that is leaking at the surface of the earth will be more concentrated in the area of the soil that has the higher conductivity from the dissolved metal ions of long time buried metal. This can be measured as an anomaly of reduced local voltage gradient in the air above the target. The movement of leakage current will be greater above the target than the surrounding air, and the voltage gradient will be less. This anomaly is highly influenced by the relative humidity of the air as well as other factors such as time of day, weather and solar activity.

There are many other secondary effects that have been listed by Esteban and others throughout the remote sensing forum that are also associated with the presence of long time buried metal objects. While Esteban does not specify which are the best anomalies to look for, he has said that different kinds of detectors may be needed for different tasks in finding a long time buried metal object. ie: Unshielded pistol coil detectors can be used for long range detection, but are poor for pinpointing. IR LED detectors work well for pinpointing, but are poor for long range detection, etc.

But one main central theme is the basis for Esteban's long time buried metal detecting:
The phenomenon is present in a piece of wire. The problem is only to convert it to a sound.

All the different LRL experiments that Esteban has described are attempts to select the slight fluctuation of current in a wire when it is influenced by a "phenomenon" area, and cause the wire to make a beep sound. His methods use simple electronics arranged in clever ways that most engineers would not consider, because they like better control of the signal they are looking for, and they like to fully understand the signal so they can optimize the circuitry to reject non-target noise. In order for an engineer to arrive at the point of understanding the signal, it would seem wise to learn a lot more about the minute anomalies that are associated with long time buried metal objects before building complex circuitry. The answers lie in the fields of geology, geotechnical engineering and astrophysics, as well as in a few other disciplines. You could also try to replicate some of the experiments that Esteban described using simple electronic circuits.

What I typed above is what I think Esteban believes is the mechanism of the "phenomenon". My opinion has always been that long time buried metals and the soil around them are not the same as freshly buried metals. My approach for locating long time buried metals is much different than what Esteban has done. But we can see from the results that Esteban described, his methods work just fine for him.

Best wishes,
J_P

Max · #53 05-25-2009, 07:52 AM

Quote:

Originally Posted by Fred

I no way i can find a reason why a led or any transmiting only device could be afected by a distant factor

Hi,
Ok... but this as JP stated is about claimed "effects"... let's focus on device/schematic and spot tricky signal interferences like environment light... that I think can fool readings like e.g. grass static potential can fool zahori or other electrometer like device.

Effects could be unexplainable unless we know the supposed principle of operation of such device... but that's another issue.

Kind regards,
Max

Max · #54 05-25-2009, 08:17 AM

Quote:

Originally Posted by Qiaozhi

So it's a sort of BFO, but using IR?

Hi,
without regarding the explaination of that... assuming Esteban's experiences are like described about effects (change of tone) I could see it like a BFO too.

Early BFO used just one coil , both for to transmit and "receive" signal... in practice when a metallic target was in the search head field lines it will create an increase or decrease in inductance (depending on magnetic properties of material), thus the inductance variation will lead to frequency shift , up or down in frequency, that mixed with internal-fixed oscillator would give a different "tone"... usually higher frequency for silver and other "noble" metals... and lower frequency for e.g. ferromagnetic stuff like nails.

That kind of BFO is really similar to what Esteban's reported... seems the target or target area/soil aorund can generate a shift in frequency respect to the oscillator preset (400Hz) then he said used a radio to provide audio indication of that.

I think he means the output of such IR transmitter is somehow connected to an e.g. AM radio where the tone at 400Hz is detected and produce audio at speaker. Then... when a target is pointed seems he get a different tone in the speaker... meaning that the IR transmitter changed its frequency).

Now that's different from JP report where one would expect an amplitude variation not a frequency shift... unless Esteban means that the tone change but in amplitude... not frequency.

he wrote : "So, the "phenomenon" produce a difference in the tone and occurs the detection."

all depends what he means for "difference" , if amplitude or frequency...

1. if amplitude we aren't talking of BFO but of power at transmitter that change...

2. if frequency we're talking about unusual kind of BFO

But I think he meant (like JP stated) the 1. (power variation)

Kind regards,
Max

J_Player · #55 05-25-2009, 09:07 AM

Quote:

Originally Posted by Max

That kind of BFO is really similar to what Esteban's reported... seems the target or target area/soil aorund can generate a shift in frequency respect to the oscillator preset (400Hz) then he said used a radio to provide audio indication of that.

I think he means the output of such IR transmitter is somehow connected to an e.g. AM radio where the tone at 400Hz is detected and produce audio at speaker. Then... when a target is pointed seems he get a different tone in the speaker... meaning that the IR transmitter changed its frequency).

Now that's different from JP report where one would expect an amplitude variation not a frequency shift... unless Esteban means that the tone change but in amplitude... not frequency.

he wrote : "So, the "phenomenon" produce a difference in the tone and occurs the detection."

all depends what he means for "difference" , if amplitude or frequency...

Hi Max,
When Esteban described the IR LED detection method, he said it was a simple transmitter with a comparator circuit to monitor the amplitude. "I think occurs a variation in height between the tone present in a receive" "The height of the tone changes. A simple adjustable comparator with audio generator". He then described some other experiments where he used a separate radio receiver to monitor the carrier of the IR LED. "This tone (modulation) appears as a phase shift in a receiver system".

I also had some confusion in understanding his meaning. When he said "The height of the tone changes. A simple adjustable comparator with audio generator", it sounds like he is talking about the amplitude of the carrier can be monitored by using a comparator. Then when he says it appears as a phase shift in a receiver system, I begin to suspect the carrier is modified in a more complex manner.

A clue comes from Esteban's method of sending the square wave to the IR LED. It is sent to the IR LED via capacitor, which may allow the rising and falling edges of the pulse to decay to some degree depending on the capacitor value and the current draw from the LED. If some phenomenon was interfering with the normal wave shape, then we could expect it might show as a deformation in the pulse that could stretch it, shift it, or perhaps cause it to increase or decrease in amplitude or overall power.

I would speculate that the 400 Hz carrier signal Esteban was working with was shifted in phase as a result of interference from some attribute of the "phenomenon" area. My guess is the wave shape was deformed enough to give the appearance of a wave deformation where the rising and/or falling edges become mushy, which might be seen as a phase shift. It may have also caused the average power to change, as represented by areas of higher amplitude, and/or larger area under the pulse curve when viewed on an oscilloscope. Possibly there is an overall phase shift independent of the wave shape deformation. But this is only my guess, as I have not had the opportunity to see the trace on an oscilloscope connected to Esteban's IR detector in the vicinity of long time buried metal.

The concept of an interfering influence seems simple. What seems hard to understand is what is Esteban's meaning when he describes what he observed.

Best wishes,
J_P

Qiaozhi · #56 05-25-2009, 09:43 AM

Quote:

Originally Posted by Max

I think he means the output of such IR transmitter is somehow connected to an e.g. AM radio where the tone at 400Hz is detected and produce audio at speaker. Then... when a target is pointed seems he get a different tone in the speaker... meaning that the IR transmitter changed its frequency).

Of course, you need to ask Esteban, but this is how I understood the idea:
There are two IR beams at slightly different frequencies. It is the difference frequency between these two that is somehow being detected by the AM radio. How that works I don't know.

So it appears to be a BFO, although there is no traditional RF and LO.

Max · #57 05-25-2009, 11:09 AM

Quote:

Originally Posted by Esteban

When you put 2 IR leds (modulated) in serie into a box of pistol, the tone frequency appears in the audio of the radio. You can hear with a headphone this tone.

So, the "phenomenon" produce a difference in the tone and occurs the detection.

I wish to replicate the device and show in film what's happens, but my video camera broken! Maybe if I take it with cellular...

Hi,
ok, you have an oscillator, maybe a 555, in astable mode, 50% duty cycle, 400Hz (about) frequency. the output of it is connected to 2 IR LEDs in series, so both share the same current.

Then you have a radio receiver that get the EM signal from current on-off due to the oscillator stuff at 400Hz.
I guess you use an simple amplitude modulation receiver, so a commercial portable AM radio for that, that in proximity of IR LED circuit will detect the EM signal due to commutations and give audio tone at 400Hz from the 400Hz EM signal...you have everything there at receiver already... rectifier, audio amplifier etc

Then you listen for audio changes ? Right ?

1. Ok... if audio change in frequency the explaination is like Qiaozhi stated: kind of BFO... don't know why but the EM signal change frequency and that you hear a changed frequency tone at headphones

2. If , instead, you hear stronger... so more loud the audio you get something at e.g. voltage variation at IR circuit... thus a change in e.g. power drain by IR leds is shown as a drop or increase in loudness.

So, what do you hear in presence of phenomenon ? frequency variation or loudness variation ?

Kind regards,
Max

Esteban · #58 05-25-2009, 02:52 PM

Quote:

Originally Posted by J_Player

For all who are interested in Esteban's methods of detecting long time buried metal objects:

Esteban's idea of detecting long time buried metal objects begins with what he calls "the phenomenon", sometimes called "halo" by others. The concept is that a long time buried metal object will be surrounded by soil that has different geotechnical properties than nearby soil without long time buried metal objects. The changed properties of this soil cause changes in secondary effects from existing natural and man-made energies that are found in the nearby vicinity. When all the changed properties of soil and associated secondary energies nearby are tabulated, there are many types of measurable effects from the long time buried metal object which constitute anomalies centered around the target. These anomalies are usually small in comparison to the surrounding energies, so sensitive instruments must be used to detect them.

Some of the larger anomalies that can be measured are:
1. Voltage anomaly in the soil around the long time buried metal object due to "ground battery" mechanisms from metal ions that have separated from the metal object and are combining with constituents in the soil.
2. Soil conductivity (or resistivity) anomaly in the soil, due to the presence of metal ions that have detached from the surface of the long time buried metal object and dissolved in the soil.
3. Anomaly in the space charge of the air above the long time buried metal object. This comes from the natural atmospheric leakage of current between the surface of the earth and the atmosphere. The theory is the air's charge that is leaking at the surface of the earth will be more concentrated in the area of the soil that has the higher conductivity from the dissolved metal ions of long time buried metal. This can be measured as an anomaly of reduced local voltage gradient in the air above the target. The movement of leakage current will be greater above the target than the surrounding air, and the voltage gradient will be less. This anomaly is highly influenced by the relative humidity of the air as well as other factors such as time of day, weather and solar activity.

There are many other secondary effects that have been listed by Esteban and others throughout the remote sensing forum that are also associated with the presence of long time buried metal objects. While Esteban does not specify which are the best anomalies to look for, he has said that different kinds of detectors may be needed for different tasks in finding a long time buried metal object. ie: Unshielded pistol coil detectors can be used for long range detection, but are poor for pinpointing. IR LED detectors work well for pinpointing, but are poor for long range detection, etc.

But one main central theme is the basis for Esteban's long time buried metal detecting:
The phenomenon is present in a piece of wire. The problem is only to convert it to a sound.

All the different LRL experiments that Esteban has described are attempts to select the slight fluctuation of current in a wire when it is influenced by a "phenomenon" area, and cause the wire to make a beep sound. His methods use simple electronics arranged in clever ways that most engineers would not consider, because they like better control of the signal they are looking for, and they like to fully understand the signal so they can optimize the circuitry to reject non-target noise. In order for an engineer to arrive at the point of understanding the signal, it would seem wise to learn a lot more about the minute anomalies that are associated with long time buried metal objects before building complex circuitry. The answers lie in the fields of geology, geotechnical engineering and astrophysics, as well as in a few other disciplines. You could also try to replicate some of the experiments that Esteban described using simple electronic circuits.

What I typed above is what I think Esteban believes is the mechanism of the "phenomenon". My opinion has always been that long time buried metals and the soil around them are not the same as freshly buried metals. My approach for locating long time buried metals is much different than what Esteban has done. But we can see from the results that Esteban described, his methods work just fine for him.

Best wishes,
J_P

This explanation is fine.

Regards

Esteban

Esteban · #59 05-25-2009, 03:20 PM

The common IR led can detect a coin at 7 m. Today in market are IR leds with incorporated lenses capable to send the ray at 100 m. Elektor was publish in the 80s a IR voice communicator capable to send the ray to 1,750 m, this is, 1.75 km, but uses a old car beacon, not the modern.

Max · #60 05-25-2009, 05:14 PM

Quote:

Originally Posted by Esteban

The common IR led can detect a coin at 7 m. Today in market are IR leds with incorporated lenses capable to send the ray at 100 m. Elektor was publish in the 80s a IR voice communicator capable to send the ray to 1,750 m, this is, 1.75 km, but uses a old car beacon, not the modern.

Hi,
ok...IR-based LRL , you said, can detect a coin at 7meters... so now you have to teach us HOW!

I made the driver circuit... 555, astable mode, 400Hz, 50%duty cycle that directly power two IR leds in series. The 555 is powered by stable 5V by 7805 regulator to avoid voltage floatings due to e.g. battery.

Consumption is around 100mA (depends on leds used).

Ok... here some pictures:

1. circuit (notice the quality... made of pure junk... but I think it's compatible with state of the art lrl

) + bradboard with leds
2. LD271 leds (I guess they are LD271 from what I remember) that glow bright
3. unknown metal can IR leds (760nm I think) that glow but less bright so less efficient

I put the AM radio near... and hear the "tone" at 400Hz (of course).

Now the challenge for you... teach us (poor LRL ignorants) making one that work!

So now... that you're the LRL guru here ... what I have to do with that stuff to detect a coin at 7m... ???

(I will be satisfied also with 50cm detection... just to have proofs that this stuff really work)

Kind regards,
Max

J_Player · #61 05-25-2009, 08:28 PM

Wow..! He did it!

Max built the IR LED long time buried metal detector!

I think you're sposta point the LED at long time buried metal things now and listen for a change in the tone at the radio receiver.

Best wishes,
J_P

Morgan · #62 05-25-2009, 10:56 PM

Quote:

Originally Posted by Max

Hi,
ok...IR-based LRL , you said, can detect a coin at 7meters... so now you have to teach us HOW!

I made the driver circuit... 555, astable mode, 400Hz, 50%duty cycle that directly power two IR leds in series. The 555 is powered by stable 5V by 7805 regulator to avoid voltage floatings due to e.g. battery.

Consumption is around 100mA (depends on leds used).

Ok... here some pictures:

1. circuit (notice the quality... made of pure junk... but I think it's compatible with state of the art lrl

) + bradboard with leds
2. LD271 leds (I guess they are LD271 from what I remember) that glow bright
3. unknown metal can IR leds (760nm I think) that glow but less bright so less efficient

I put the AM radio near... and hear the "tone" at 400Hz (of course).

Now the challenge for you... teach us (poor LRL ignorants) making one that work!

So now... that you're the LRL guru here ... what I have to do with that stuff to detect a coin at 7m... ???

(I will be satisfied also with 50cm detection... just to have proofs that this stuff really work)

Kind regards,
Max

After this demonstration,i only ask ,if you are a skeptic about LRL´s(you call lier to me and Esteban many times),WHY YOU SPEND TIME BUILDING THIS DEVICES ?

Fred · #63 05-25-2009, 11:52 PM

I think Max finally found complete information about how to build a LRL so he is doing it...

Esteban · #64 05-26-2009, 01:08 AM

Quote:

Originally Posted by Max

Hi,
ok...IR-based LRL , you said, can detect a coin at 7meters... so now you have to teach us HOW!

I made the driver circuit... 555, astable mode, 400Hz, 50%duty cycle that directly power two IR leds in series. The 555 is powered by stable 5V by 7805 regulator to avoid voltage floatings due to e.g. battery.

Consumption is around 100mA (depends on leds used).

Ok... here some pictures:

1. circuit (notice the quality... made of pure junk... but I think it's compatible with state of the art lrl

) + bradboard with leds
2. LD271 leds (I guess they are LD271 from what I remember) that glow bright
3. unknown metal can IR leds (760nm I think) that glow but less bright so less efficient

I put the AM radio near... and hear the "tone" at 400Hz (of course).

Now the challenge for you... teach us (poor LRL ignorants) making one that work!

So now... that you're the LRL guru here ... what I have to do with that stuff to detect a coin at 7m... ???

(I will be satisfied also with 50cm detection... just to have proofs that this stuff really work)

Kind regards,
Max

You are a champion revealing your attitude!

Max · #65 05-26-2009, 07:51 AM

Quote:

Originally Posted by Morgan

After this demonstration,i only ask ,if you are a skeptic about LRL´s(you call lier to me and Esteban many times),WHY YOU SPEND TIME BUILDING THIS DEVICES ?

Hi,
uhm... took 20minutes maybe... some junk parts... why not.
In the case it doesn't work (as probably is and I think of it) I will add to my non-sense collection!

But now... that you're experts ...why don't help make this one reach 7meters on a coin!?

As you can see I'm experimenting...following Esteban's claims and descriptions... so I'm not closed mind about LRL... or not ?

Kind regards,
Max

Max · #66 05-26-2009, 07:54 AM

Quote:

Originally Posted by Fred

I think Max finally found complete information about how to build a LRL so he is doing it...

Hi,
no, no... I'm doing as Esteban described... now he can help me to reach that 7meters with this simple device... or even 50cm doesn't matter... I just wanna see if "principle" works as Esteban claimed or not!

If anyone wanna try I will post schematic and components bill... (though it's very basic astable 555 and hope anyone can make such calculations...)

Kind regards,
Max

Max · #67 05-26-2009, 07:57 AM

Quote:

Originally Posted by Esteban

You are a champion revealing your attitude!

Hi,
and you're a champion claiming that an IR stuff detects coin at 7meters... than give no hints or clues how to make it work ?

Now... if you're serious about IR LRL detector you'll explain me (us) how to implement or tune this... "device" to get such far detection...

As you can see I spent TIME and EFFORTS for doing this thing you said... and would like to have some RESULT!

Or now... that we are at practical scenario you refuse to give more informations ?

Kind regards,
Max

Max · #68 05-26-2009, 01:22 PM

Hi,
just a couple of pictures about progresses...

Added hot-melt glue... some hard cardboard (?) from trash... and the AM radio... what do you think ...could that stuff detect a coin at 7meters ?

BTW I've added funky component like loop-antenna wired in series with IR diodes...uh!

Now signal at AM radio is VERY strong indeed!

Esteban what do you think ? is that design compatible with 7meters coin detection ?

Hope you'll give hints about...

Kind regards,
Max

Esteban · #69 05-26-2009, 02:31 PM

Quote:

Originally Posted by Max

Hi,
and you're a champion claiming that an IR stuff detects coin at 7meters... than give no hints or clues how to make it work ?

Now... if you're serious about IR LRL detector you'll explain me (us) how to implement or tune this... "device" to get such far detection...

As you can see I spent TIME and EFFORTS for doing this thing you said... and would like to have some RESULT!

Or now... that we are at practical scenario you refuse to give more informations ?

Kind regards,
Max

As you said, you spent 20 MINUTES and EFFORT with this junk. Maybe you need to spent 20 years and effort in such junks!

Esteban · #70 05-26-2009, 02:39 PM

Quote:

Originally Posted by Max

Hi,
and you're a champion claiming that an IR stuff detects coin at 7meters... than give no hints or clues how to make it work ?

Now... if you're serious about IR LRL detector you'll explain me (us) how to implement or tune this... "device" to get such far detection...

As you can see I spent TIME and EFFORTS for doing this thing you said... and would like to have some RESULT!

Or now... that we are at practical scenario you refuse to give more informations ?

Kind regards,
Max

All the time I give hints and clues, but if you don't pay a minimun of attention I can't repeat it all the time.

As Mr. A. said to me: "If I give all the secret to others, of others will be the credit".

Esteban · #71 05-26-2009, 02:42 PM

Quote:

Originally Posted by Max

Hi,
just a couple of pictures about progresses...

Added hot-melt glue... some hard cardboard (?) from trash... and the AM radio... what do you think ...could that stuff detect a coin at 7meters ?

BTW I've added funky component like loop-antenna wired in series with IR diodes...uh!

Now signal at AM radio is VERY strong indeed!

Esteban what do you think ? is that design compatible with 7meters coin detection ?

Hope you'll give hints about...

Kind regards,
Max

Said me, and demonstrate me, in wich part I said that I use in AM mode! Do you see? ... but if you don't pay a minimun of attention I can't repeat it all the time.

Qiaozhi · #72 05-26-2009, 02:45 PM

Quote:

Originally Posted by Max

Hi,
just a couple of pictures about progresses...

Added hot-melt glue... some hard cardboard (?) from trash... and the AM radio... what do you think ...could that stuff detect a coin at 7meters ?

BTW I've added funky component like loop-antenna wired in series with IR diodes...uh!

Now signal at AM radio is VERY strong indeed!

Esteban what do you think ? is that design compatible with 7meters coin detection ?

Hope you'll give hints about...

Kind regards,
Max

So what happens when a metal target is passed in front of the LEDs?

Esteban · #73 05-26-2009, 02:49 PM

Quote:

Originally Posted by Qiaozhi

So what happens when a metal target is passed in front of the LEDs?

This is a wrong construction! First of all, as is in AM mode, if you pass a regular size metal, can be a detection but because the ferrite is affected.