Circuit Mod to increase range to Harbor Freight Cen-tech pinpointer

[wingryder]

These are so cheap I have two and looking for circuit modifications to increase the range. I know about the tweaking and the sliding ring trick, but I want a simple circuit mod even if it required additional parts to make the range a little better. How about one of you retired electronics wizards putting your skills to work for the rest of us? Maybe just replacing the cheapo parts with better ones would do it.
And please don't make this a Propointer ad. I love Garrett's but I would rather put my 127.00 towards a new AT Pro.

Thanks for any help.

wingryder

 

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[DirtyDon]

I almost doubled the sensitivity by opening the box and readjusted the blue pot on the right side of the circuit board. Takes a little messing around but it worked for me.

 

[Frankn]

Hay, don't make it to sensitive or it will not be selective in the hole. The adjustment knob and the blue pot should do it for you. And if you want to run silent just put a led across the signal coil. I have added a bright blue Led to mine. Frank

 

[YosamiteDig]

I almost doubled the sensitivity by opening the box and readjusted the blue pot on the right side of the circuit board. Takes a little messing around but it worked for me.

I did the same to mine. It will sense a dime from 1-1/2 away which is sufficiant for me. Lets me know when the target is very close. I also added the plastic table leg cap to the end of the wand.

 

[woodstock]

I've modded HP Pinpointer and it's not hard and takes about 2 hours or less and costs about $8 for parts from RS. I installed a better push on, push off switch. That will take a rat tail file to make the old hole a tad larger. I got rid of the pezo speaker and installed a vibrator motor in it's place and put a toggle switch on the light so can opt for the light only if needed. I adjusted the blue sensitivity control with the brass screw (be careful not to strip it) and hard waxed it in place after adjusting. I also put an O ring under the sensitivity knob to hold it in place and then put o a larger knob to adjust it simpler.
So for about $25 or $26 I had a pinpointer better than any Bullseye. I don't have either anymore cause I use a SunRay but if I ever need another I won't hesitate to do this again. Happy Trails, Woodstock

 

[Afro]

How is this for insurance after your upgrade?

HF sells tough as nails nitrile gloves.
Put a rounded rubber cap onto the end of the probe, doesn't have to fit snugly, the glove will hold it in place.
Put your Cen-Tech into the glove with the probe down the index finger.
Invaginate (been waiting a long time to use that word) all the other fingers.
Put the vacuum cleaner nozzle into the wrist and suck out all the air around the probe.
Stretch the wrist of the glove and get someone else to tie it off tight.
Cut off the extra bit of glove.

Now you have a weather protected probe!

 

[deteknix]

I tried to modify a centech pinpointmetal detector but the IC is designed for that detection range only.

 

[KLLJr]

Hey Wingryder,

What is the "tweaking and the sliding ring trick"? On a tight budget and could use some insight.

Thanks!