hello dr.jare ,
have tried with smaller coin , nickle based , uk 10p , 24mm dia and 2mm thick , starts to pick it up at a distance of about 30 cm , clear at 25cm.
tried it with 9ct gold ring 4mm x 4mm cross section , same 25cm to 30 cm , but then its a complete circle , which are easyer to detect regardless of metal ,
tried a 9ct very thin light chain in a ball , distance very poor , about 8cm.
hello smity and thanbo ,
the slightly modified finished version of the blind squirrel is the last one posted by 6666 on the thread ,
it's not a compleatly new detector , i just did a few mods to the existing design to "thin it down" a bit and use more common parts , whilst trying to maintain simplicity to build / setup and performance , may not have got perfection , but it works , and performance is similar to most other single sample machines.
thanbo , i would recomend building either original blind squirrel or the slightly modified one on here , recomend the modified one , as the original one with the opto coupler gives a constant clicking regardless of no target , which is anoying and makes adjusting the threshold anoying , however , if the original design has a 10uf cap from the emmiter of the opto ,and a 5.6v zenner in series with a 10k to the opto emmiter , then the audio works well , and very progressive, i just opted for an npn for simplicity.
i think i'm like you , i pondered for ages picking a design to build for the first time , and settled for the squirrel , simple and it works , and its a non-movement machine , so good for pin pointing.
the idea i'm working on at the moment is not based on the blind squirrel , appart from the use of the 4538 / 4098 dual monostable timming chip for dual sample pulses ,
just piecing something together gradualy ,
my goals are , simple to opperate for everyone minimal setup / controls , automatic and manual zero , some form of discrimination , worked out a simple way for FE and non-FE but also working on a simple way to show metal conductivity on a scale using 10 led's , but changing ground conditions are hampering any precision there.
may need 3 samples , one for ground , and minus it off for stability , not sure yet.
recently had the time to experiment , but starting new job next week , so time will be limited then , so don't hold youre breath for a finished project.
will post and share only when i'm happy with performance , as i don't want to look an idiot , anyway the "big boys" designers are now on ecu's so my little project's / designs will never make me rich so share with the people , only fear left is some boffin finding fault , hell , were all trying , no body's perfect.
Posted on: August 24, 2011, 02:31:09 PM
OH smity ,
nearly forgot , youre project name is a bit long winded , as i said to 6666 , didnt want to rename an existing design , that remains the child of the original designer and should remain so,
new project , regarding a name , i have given some thought to, if it works , not very imaginitive regarding naming something , however , i am keeping in a folder on my pc simply called MYPI , but thats just plain and silly for a name ,
BIG NAMES , of things have to be forthright and forcefull and out there like : the TDI , GTI or the BARRACUDA or MUSTANG ,
or have mystical names like : ATLANTIS , HOGWARTS or HUNDRED ACRE WOODS , sorry humour there.
conclusion , i have a total lack of imagination , society has drained it from me.
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