2 boxxxx :)

[nelson]

TR locator errors

Hi Geo.
Well it looks that this detector is full of errors. My question is if anyone had made it and how was the results. After that, may be we can get the correct schematic and try to have a two box that really works.
May be with the knolegment of Carl, Gary, you or other that can really look the schematic, because i don´t have that level of knolegments.
Last question, what do you think of simulatin software for electronics. May be we can test this circuit thru simulation.
Regards and thanks
Nelson

Ohh another error . At U5 you must connect pin8 to -6V and pin16 to +6v.

[chemelec]

Hi Geo.
Well it looks that this detector is full of errors. My question is if anyone had made it and how was the results. After that, may be we can get the correct schematic and try to have a two box that really works.
May be with the knolegment of Carl, Gary, you or other that can really look the schematic, because i don´t have that level of knolegments.
Last question, what do you think of simulatin software for electronics. May be we can test this circuit thru simulation.
Regards and thanks
Nelson

If everyone could decide on One Set of IC's they want to use, I could possibly Re-Design a Corrected Circuit board for this detector.

4049, 4069 or ???.

If its either the 4049 or 4069, I could possibly even build and test it.

[nelson]

TR locator

Excellent Gary. Yes i agree with you, that we must define the correct IC.
I sudgest 4069, because is easy to find on most electronics part suppliers.
If you give it a try i can tell you that the pcb construction is very easy and parts placement too. The pcb has enough space to make corrections and mods.
So Gary i´ll be waiting for your news.
Thanks and best regards
Nelson

If everyone could decide on One Set of IC's they want to use, I could possibly Re-Design a Corrected Circuit board for this detector.

4049, 4069 or ???.

If its either the 4049 or 4069, I could possibly even build and test it.

[chemelec]

Excellent Gary. Yes i agree with you, that we must define the correct IC.
I sudgest 4069, because is easy to find on most electronics part suppliers.
If you give it a try i can tell you that the pcb construction is very easy and parts placement too. The pcb has enough space to make corrections and mods.
So Gary i´ll be waiting for your news.
Thanks and best regards
Nelson

How about Comments from others here?

However If I were to do it, I would do it from Scratch.

To edit the existing one must be done in a Graphics program.

Doing it from scratch, I would use my PCB design progam. Much easier.

I would also like to see some Test Results from the Origional Person who built this.

For Example: "At what distance will it detect What size Objects?"

[kt315]

How about Comments from others here?

However If I were to do it, I would do it from Scratch.

To edit the existing one must be done in a Graphics program.

Doing it from scratch, I would use my PCB design progam. Much easier.

I would also like to see some Test Results from the Origional Person who built this.

For Example: "At what distance will it detect What size Objects?"

hi Garry. it detects a sheet 50х150 sm on distance 3 meters, on air, car on 4 meters (but I very doubt that you will be able dig on 1 m! ). I read Ivan suggests even to go on more low frequency, you can connect any pin of the divider on TX driver and get low freq. then enfliuence of ground must be very decrease with a sencitivity increase on metall.

[kt315]

one thing guys do in our part of world. you must remember that RX opamp way be in overload on testing. pls connect the diodes for the guard according the schematic.

[chemelec]

one thing guys do in our part of world. you must remember that RX opamp way be in overload on testing. pls connect the diodes for the guard according the schematic.

Yes, Definately a Good Idea, especially since its the Lowest Signals that are Most Important.

Another Point: Why use the Crystal and a Frequency divider. I Doubt the frequency needs to be that stable.

Why not just use a 555 Oscillator and have a continuously Variable Frequency. This way you can Fine Tune the Frequency to the Resonance of the Coil/Cap.
I find that with a Regulated supply, 555 oscillators stay quite stable. Assuming the temperature remains fairly constant.
Much Simpler Circuit and by doing this, Re-Adjustment is also easy.

Just a Thought...Gary

[Geo]

Hi Gary.
Very good idea . At 2box detectors a change at frequency between +-2% has not change at the detector efficiency. So 555 will be a perfect solution (simple and cheap) for so low frequencies.

[Chris2]

Hi all,

555 Timer is okay...but you still need the GATE IC for the TX circuit! With a 555 timer is no real saving on components & IC chips...and a crystal is cheaper than the components around the 555 timer (poti's, resistor, caps etc.).


Chris

[kt315]

Chris, I full agree with you. any VLF schematic has many unstabilities, thermo, mehanical etc. so crystal kills one of them. brands had went on crystal onetime and I do not see they want or need be change back off. btw, modern, newest, all PI and VLF schematics on a chip are crystalled. we see the way continues from Fisher 1266' and Whites 5900' bronze era before now.

[chemelec]

Chris, I full agree with you. any VLF schematic has many unstabilities, thermo, mehanical etc. so crystal kills one of them. brands had went on crystal onetime and I do not see they want or need be change back off. btw, modern, newest, all PI and VLF schematics on a chip are crystalled. we see the way continues from Fisher 1266' and Whites 5900' bronze era before now.

OK. I'll do it as Is, but with the 4069.
First, I'll re-do the schematic, than the PCB afterwards.

Would it be good to put HeatSinks on Q4, Q5, Q6 & Q7?

[Geo]

Hi All. I agree that especially at VLF is better to use a crystal oscilator. But at 2Box oscilators with one 555 and one transistor we are ok. The stability is very good for 2box detector. Now about cost... no problem anyway. The gain is a simple and stable oscilator.

[nelson]

2 box

Hi Gary and all friend on the forum.
I was out of the city and now retorning from the beach.
Great great great idea what Gary is doing, so i ll be following comments about this re-design, so on this way i can learn more about the circuit it self.
Good luck Gary and thanks for supporting this hobby.
Regards
Nelson

Hi All. I agree that especially at VLF is better to use a crystal oscilator. But at 2Box oscilators with one 555 and one transistor we are ok. The stability is very good for 2box detector. Now about cost... no problem anyway. The gain is a simple and stable oscilator.

[kt315]

OK. I'll do it as Is, but with the 4069.
First, I'll re-do the schematic, than the PCB afterwards.

Would it be good to put HeatSinks on Q4, Q5, Q6 & Q7?

I yet have run across forum what people write about it. there is not big heating of them but only if the resonance is tuned on maximum. somebody wrote he uses IRF7309 in half-bridge driver and same is cold.

regards

[detectoman]

chemelec, in past post, he show one tx whit 555, on modifications at two boxs of rakes, after also he discontinued these idea and project, please say why?
detectoman