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Simple RF LED Pen

Discussion in 'CB and Export Equipment and Accessories' started by Crossbow, Nov 8, 2018.

  1. Crossbow

    Crossbow Active Member

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    Here is a simple RF LED Pen I made up for the bench. Hope this helps someone else.
    Parts needed:
    1- 1n4148 Switching Diode
    1- 10pf Cap
    1- Stick Pin
    1- LED
    1- Gator Clip
    1- Ground wire
    1- Sharpie



    IMG_0496.JPG
    IMG_0497.JPG
    IMG_0500.JPG
    IMG_0498.JPG
     

  2. kaos513

    kaos513 Well-Known Member

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    Great job
     
    Crossbow likes this.
  3. Crossbow

    Crossbow Active Member

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    Thanks Kaos!
     
  4. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    That s a fun little device to own.

    Can you tell us a little more about though?

    Like - how did you come up with this idea?

    Its KEWL - reminds me of the older "plug tester" neon bulb - used to find Hot from Neutral.
     
    Crossbow and Shadetree Mechanic like this.
  5. Ranch55

    Ranch55 Well-Known Member

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    Yep, I made one for myself about 1 1/2 years ago. Except I did not put the components inside of anything. I just use it as it is .....
    Works damn good for following the RF path and troubleshooting .....
     
  6. Crossbow

    Crossbow Active Member

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    I built this thing over a couple years ago. I looked at a lot of other people building all types of RF tracers that had what I called an over kill so I toyed with the idea for a bit and figured out a simple way of making one that was simple by using very little parts and worked out great for me. Just figured I would share with others on this site.
     
  7. Crossbow

    Crossbow Active Member

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    Yeah I built this one a couple years ago. It has been a life saver no doubt. So simple to build and works like a charm.
     
  8. loosecannon

    loosecannon Sr. Member

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    great idea Crossbow!

    i haven't looked at the circuit, but is there enough RF coming in to a radio's antenna socket (no signal) to turn the LED on?
    LC
     
    Crossbow likes this.
  9. kaos513

    kaos513 Well-Known Member

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    Yes sir cb radios have strong rf.
     
    Crossbow likes this.
  10. Crossbow

    Crossbow Active Member

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    This one was made for TX only.
     
  11. Crossbow

    Crossbow Active Member

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    Digging through my notes I found another one that I had built. This one can use a 12 volt meter build instead of a LED. Have to use a 9 volt battery on this one. I never put it in a case as the one I posted above works well with out all the extra parts and battery. Hope you enjoy.
    IMG_0502.JPG
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    rf-pen.jpg
     
  12. Shockwave

    Shockwave Sr. Member

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    Very nice way to check for RF without risking the scope or probe. Adding an analog meter gives you the ability to check for balance in multi transistor amplifiers. Just use a low enough value coupling cap to prevent the rectifier from loading the circuit or burning up from too much RF. Many older VOM's can be converted into an RF meter just by placing a 1N60 diode across the meter movement. That diode is more sensitive to RF and needs less drive.
     
    Shadetree Mechanic and Crossbow like this.

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