METAL DETECTOR "INTEGRATED CIRCUIT" APPLICATIONS..

[simonbaker]

Hello 1843,simonbaker and all , the "circuit analysis" posting's are almost ready to begin !!! I have been side-tracked working on PCB software. I Have 5 or 6 schematics ready for disection and they are very popular metal detector circuit's .So , "one schematic at a time" I will describe the function of each of the detector stages and what the different types of component's are doing . And I will try to keep it as simple and short as possible. Hopefully just a few paragraphs, not an encyclopedia !! I will also learn from the feedback I recieve. Thanks for your patient's .................Eugene

Excellent, looking forward to it!

[amtech2005]

METAL DETECTOR "INTEGRATED CIRCUIT" APPLICATIONS...

Hello, I have not decided yet , if I will put the "Circuit Analysis" and all associated Images , schematics in a "zip file" or a "pdf file" to make it easy for everyone to copy or if I am just going to type it in the post ??? Just an example: the PDF attachment might be titled "Whites Liberty III-Circuit description and anlysis". Or another file might be titled "Tesoro Cutless II-Circuit description and analysis". I want this to be as Profesional and accurate as possible. I am still gathering information on schematics. A lot of work for me so far !! Once it finally get's going should be very informative................Eugene

[simonbaker]

Hello, I have not decided yet , if I will put the "Circuit Analysis" and all associated Images , schematics in a "zip file" or a "pdf file" to make it easy for everyone to copy or if I am just going to type it in the post ??? Just an example: the PDF attachment might be titled "Whites Liberty III-Circuit description and anlysis". Or another file might be titled "Tesoro Cutless II-Circuit description and analysis". I want this to be as Profesional and accurate as possible. I am still gathering information on schematics. A lot of work for me so far !! Once it finally get's going should be very informative................Eugene

A zip and/or PDF is definitely preferred over typing in.

We appreciate your efforts!

[amtech2005]

"CIRCUIT ANALYSIS"

I have not forgotten about my promise , but I have been very busy !!!!! Tesoro will be the first group of Metal Detector's we will analyse , one at a time !!!!! I am still working on this and getting it ready !!!! Some of the models we will study are:
1.Tesoro Royal Sabre
2.Tesoro Eldorado
3.Tesoro Silver Saber
4.Tesoro Toltec
5.Tesoro Lobo
6.Tesoro Bandido
7.Tesoro Inca

The above will be plenty enough to get a Good Idea on just how Tesoro's work. And also they are my favorite brand of Metal Detector's........Eugene

[simonbaker]

Excellent choice, I'm attracted to the no-frills design and good performance of Tesoro detectors.

Hopefully we can eventually highlight what is the same and what is different between the models to simplify our understanding of the basic techniques.

There are only so many ways you can analyze a signal. I hope we can always be clear on what parameters are being analyzed by a circuit. Such as:

- phase difference between TX and RX signals.
- amplitude change of TX when encountering a target.
- amplitude change of RX when encountering a target.
- absolute amplitude of RX when encountering a target.
- perhaps width/duration of detected signal change (depends on swing speed).
- perhaps wave shape of RX.
- if multiple simultaneous frequencies, ratios of the above responses for different frequencies might be important information.
- others?

Also we should be very clear about whether parts of the circuit are about detection or discrimination. In other words, if we wanted to simplify and have an "all metal" detector, what parts of the circuit could we throw out?

Some circuit design may be for extending battery life by not wasting power; we should look for that also and understand why certain choices may be for reduced power.

Some circuit design may be for low noise -- that is important to look for and understand.

This is very exciting, I am very interested in the basic physics and electronics of how detectors work!

Thanks for your continued work!

-SB

[amtech2005]

"Circuit Analysis"

SimonBaker , Good evening !!!! I read your post and see the topics you are interested in, or already know , but would like to be refreshed. This will be the first complete Metal Detector "Circuit Analysis" Classroom of its kind in the world. So when I start posting I can not make a mistake . Why ,because this forum alone has almost 700 current active members who each , have a "ton of knowledge and expertise" in fields that are directly or indirectly related to Metal Detection and or Geotechnology. The areas we will discuss on each metal detector circuit may include TX , RX , Phase shift , Discrimination , ground balance , dc samples , filter circuits, motion , non motion , comparators , analog to digital conversion , threshold , audio circuits , just to name a few. Here is the updated list , and in the order we will proceed . Also I put down the year when the Tesoro detector was first manufactured . I am not sure on the approximate start date of "CIRCUIT ANALYSIS" , but it is getting closer !!!!!Thanks again for your patients . This "Circuit Analysis" classroom will be worth waiting for !!!!
MODEL YEAR
1.Tesoro Aztec 1981
2.Tesoro Golden Sabre 1985
3.Tesoro Royal Sabre 1986
4.Tesoro Eldorado 1986
5.Tesoro Silver Sabre Plus 1986
6.Tesoro Lobo VLF 1989
7.Tesoro Bandido II 1993

All the above models and their associated schematics are Discontinued and no longer being manufactured , and can be dissected and analysed .But We can not do this with a new model that is being manufactured and sold as we speak..............Thanks again ...Eugene

[simonbaker]

Sounds very good, your efforts are much appreciated. We'll wait patiently.

[simonbaker]

TGSL voltage regulation

There is no filter capacitor on LM7808 output in TGSL circuit, just on input.

Wouldn't it be good to have some kind of cap on L7808 output (the positive rail)?

Also because input is battery, probably don't need such a big input cap either.

What do you think? (I put question in this thread because it is a beginners question kind of - obviously the circuit works great as is).

[simonbaker]

There is no filter capacitor on LM7808 output in TGSL circuit, just on input.

Wouldn't it be good to have some kind of cap on L7808 output (the positive rail)?

Also because input is battery, probably don't need such a big input cap either.

What do you think? (I put question in this thread because it is a beginners question kind of - obviously the circuit works great as is).

I'll answer myself -- I just remembered - the speaker runs straight off the battery +12v -- that no doubt puts hefty spikes on the unregulated battery V+. That's a good reason to have the LM78xx regulator (even with rechargeables), to isolate rest of circuit. I still would be tempted to put some kind of capacitor on the LM78xx +8v output though -- but maybe the drain is very smooth.