I just picked up a poorman's cen-tech. Was going to pass it by. However, found a link on the net where some grizzled dectorists discussed improvements to the unit. i.e., install new on/off switch, replace speaker with buzzer from cell phone, increase depth by adjusting inside unit tuner with outside tuning, etc. Apparently they ended up with much more depth and sensitivity than many higher priced units.
I read this in another forum.
I tried it and it turns the Cen-Tech into as good a pinpointer as the more expensive units.
The key is that this unit was made for finding nails in wood, not coin shooting. By changing the factory settings you turn your Cen-Tech into a fine coin pinpointer
Do an air check using any coin to see what distance you have at the factory setting.
Open the box by removing the 4 corner screws. Don't remove the center screw.
With the probe pointing to the left, you will see a little blue box on the upper right.
You will see a little adjustment screw on top of that box.
Turning that screw clockwise raises the sensitivity.
Turn the external sensitivity knob about 1/2 turn.
Turn the internal sensitivity screw clockwise until the unit sounds off.
By doing a little tinkering with the 2 controls, you should be able to get the Cen-Tech to detect a penny at about 2".
Be sure to leave a little play in the outside knob to help narrow your search once you locate your target.
I mounted a Radio Shack 1/2" Blue-Capped control knob, part no. 274-403, over the factory control knob. Now I don't have to use 2 fingers to adjust that tiny knob. It looks better too.
By the way. I do wonder why people need a hundred dollar pinpointer that that will detect at 3+ inches.
Let me know how this tweek works out for you.
Will let you know how I make out with the modifications.
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