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My first project ever -Remake- Simple Needle DetectorAuthor
Giorgos Lazaridis
June 14, 2013

So, here it is! This is (as far as i can remember) my very first electronic project. I was about 7 years old when i made this one. Being a practical mind from my swing (as it seems), i noticed that my grandmother had a hard time searching for needles on the carpet. She used to like knitting a lot. Some times, a needle or pin was lost in the carpet which was dangerous for a seven years old bare-footed (that was me). So she had to search for it. I really do not remember the route of my thinking and how i finally came up with this idea. I certainly remember though how happy and proud i made my grandmother. Plus, this project was the sign that my father saw - From that year after, my father had a surprise for me (tech-wise of course)!

The Idea
As i said, i do not remember how my thinking evolved to this project. Was it the need to make a needle detector that lead me to this project, OR i accidentally winded 2 wires and found out that i could make a needle detector? ...

Anyway, the idea was to make a "switch" actuated by the needles themselves. Two bare wires side by side perform this switch. Should a needle touch these wires, the switch would close to energize a flash. Making something more sophisticated was simply not possible, first because finding electronic parts in Greece back in the mid 80's was a joke and second because i had zero knowledge on electronics.

The remake
I'm not sure what happened to the original pin detector. I only managed to find the original flash from my father's Yashca camera. As far as i can remember, having my father seen the pin detector, he bought me a cheaper flash to use it instead.

I began with the round wooden stick from a mop or cleaner... The mop itself is not needed Then i cut a 20 to 30cm long piece out of this pole

My grandfather helped me to secure the small piece with a V-slot Maybe i used some glue as well? Not sure Then, i nailed the small piece to make a T-shaped structure My grandfather helped me a lot with this


Making the switch

Fist i fixed with screws some wire terminals One on each side I used old telephone wire, similar with this UTP, only thicker A pair of this wire was used

Then i stripped the wire I winded the first wire around the 25cm piece with pitch about 1cm Then i winded the second wire WITHOUT touching the first

A final touch - duct tape hold the wires in place (the bottom side is still exposed)

The wires must NOT touch each-other. The ohm-meter shows infinite resistance And this is the pin to be found! The pin touches the wires and the "switch" is closed having minimum resistance The pin is supposed to touch both wires

The flash indicator

This is my father's camera And this is the original flash that i used first After many years, i had to open it and clean it. One contact inside was not working. Temporarily for this presentation, i used an external wire

I fixed the flash with electric wire Then i extended the flash switching wires with my detector switch The flash connects to the detector switch using the wires terminals.



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  • At 15 March 2014, 3:16:03 user Neeraj Badhani wrote:   [reply @ Neeraj Badhani]
    • ExxCelllent..joB...
      KeeP iT Up..
      And Keep Updating Us...
      Thanks A LOT....

  • At 30 August 2013, 16:29:08 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Arron Well, here is my advice: First discover what you like to do - automation? robots? radio control? Digital? Analog? Then go ahead and find circuits that fits your interests. This will be a good start. You will see that slowly you will find your path.

  • At 8 August 2013, 20:43:00 user Arron wrote:   [reply @ Arron]
    • Hi Giorgos,

      my name is Arron,

      I was wondering if you could give me some advice, i have been looking at your website/projects all are great but all this goes way over my head, i was looking to get into making things with circuit boards and stuff can you give me any advice as to where to start, i have no electronics experience. Any advice would be greatly appreciated.

      many thanks


  • At 2 July 2013, 16:07:25 user yusuf ishaq wrote:   [reply @ yusuf ishaq]
    • Hi Giorgos! My name is Yusuf Ishaq. Am a Nigerian and I've been duplicating your circuit for quite some time now. All of which works like a charm. But never had the opportunity to comment on any one of them. You are one of the great minds that inspires me on electronics and engineering in general. Thanks!

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