01-03-2021, 09:46 PM
301
Re: Foxy's Latest Project.
Originally Posted by Minx
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Apparently, there may be pieces of meteor scattered in Cheltenham. It’s providence! Time for a test run !
01-03-2021, 10:09 PM
302
Re: Foxy's Latest Project.
Originally Posted by Fruitcake
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Sadly, driving from Oop Norf to the top end of the South West is not currently permitted at the moment.
01-03-2021, 10:14 PM
303
Re: Foxy's Latest Project.
Originally Posted by Minx
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Apparently, there may be pieces of meteor scattered in Cheltenham. It’s providence! Time for a test run !
10-03-2021, 11:52 AM
305
Re: Foxy's Latest Project.
A small 'hickup' has occurred with the metal detector...I say 'Hickup' more of a teething problem really....I have been testing it out looking for old roman coins on my lawn 'As you do' and I found that the longer that I used the device, the more adjustment it needed, until finally after several minutes I ran out of adjustment. I concluded that it must be the load on such a small battery (PP3) was gradually running the battery flat. This was confirmed by a quick check of the battery, which was found to be low on charge after very little use.
I connected six AA batteries in series to produce the 9 volts required to power the machine and continued my search of the garden. After several minutes of operation, and no roman coins, I had once again run out of adjustment....
Plan 'B'...I realised that something was getting warm...A resistor that gets warm diminishes its ability to resist and the result would be a continual need to adjust. Also, Some of the resistors required for the circuit did specify a particular wattage, of which I did observe in most cases but not all....There were two resistors of the same value (68k ohms 2 watt) that I was unable to source, so I used two 68k ones from my extensive collection, but sadly they might not have been 2 watt versions.
So with the unit operational I delved around with a probe from a digital thermometer. I did manage to find a resistor that had increased in temperature by one degree C, but it was not the suspect resistors, and all other components seemed to be stable. So later on I will add a makeshift heatsink to the suspect component and see what happens......Happy Days...
10-03-2021, 12:43 PM
306
Re: Foxy's Latest Project.
Originally Posted by OldGreyFox
->
A small 'hickup' has occurred with the metal detector...I say 'Hickup' more of a teething problem really....I have been testing it out looking for old roman coins on my lawn 'As you do' and I found that the longer that I used the device, the more adjustment it needed, until finally after several minutes I ran out of adjustment. I concluded that it must be the load on such a small battery (PP3) was gradually running the battery flat. This was confirmed by a quick check of the battery, which was found to be low on charge after very little use.
I connected six AA batteries in series to produce the 9 volts required to power the machine and continued my search of the garden. After several minutes of operation, and no roman coins, I had once again run out of adjustment....
Plan 'B'...I realised that something was getting warm...A resistor that gets warm diminishes its ability to resist and the result would be a continual need to adjust. Also, Some of the resistors required for the circuit did specify a particular wattage, of which I did observe in most cases but not all....There were two resistors of the same value (68k ohms 2 watt) that I was unable to source, so I used two 68k ones from my extensive collection, but sadly they might not have been 2 watt versions.
So with the unit operational I delved around with a probe from a digital thermometer. I did manage to find a resistor that had increased in temperature by one degree C, but it was not the suspect resistors, and all other components seemed to be stable. So later on I will add a makeshift heatsink to the suspect component and see what happens......Happy Days...
In addition to a heatsink, how about a small fan as well?
10-03-2021, 12:53 PM
307
Re: Foxy's Latest Project.
Originally Posted by JBR
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Well you seem to have it all in hand, OGF. I'm sure you'll sort it out and I wish you the best of luck.In addition to a heatsink, how about a small fan as well?
10-03-2021, 09:12 PM
309
Re: Foxy's Latest Project.
Originally Posted by Fruitcake
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Surely the simplest solution for a big strong lad like you is to strap a car battery, or better yet a leisure battery to your back.
) Fruitcake, I had actually considered carrying a rucksack with a larger power supply should the device be power hungry, or I was intending to spend long hours searching for the Yorkshire Hoard...But the jury is still out on both.Incidentally, the heat sink on the resistor made no difference, so we move into plan 'C'.....
Increasing the size of the control potentiometer....
10-03-2021, 09:22 PM
310
Re: Foxy's Latest Project.
Once you get it fired up, Foxy....come and find the hidden gold in the Highlands ala Garnet Frosthttps://www.youtube.com/watch?v=wOSoCxsvgn0
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