Modified Harbor Freight Pinpointer w/ pics

[Ice Scratcher]

Cen-Tech designed a NTC thermistor into the circuit but I guess they decided it cost too much to install it.

Guys,

Is there anyone that might be able to help me get my hands on one of those..

I don't have credit cards or pay pal, but I would gladly send someone cash $5, plus a couple bucks for shipping if they were nice enough to send one back to me?

Or is this something one could find living near a bigger city?

Thanks guys!!

<*)))>{

 

[TCosbyJr]

Guys,

Is there anyone that might be able to help me get my hands on one of those..

Or is this something one could find living near a bigger city?

Indeed any larger city should have a electronics parts store that would carry them. Usaully the trick is in finding the store. I would recommend doing a Google search - type in your city and state and electronics store. Google will show you a list of the electronic stores in your area.

For example here are the results for the nearby city for me, and the first store listed has them in stock.

Check your PM box (private message) as well as I sent you a message.

 

[Ice Scratcher]

TCosbyJr,

Hey thanks a bunch for your offer, and help! I PMed you back but...

You said "the first store listed has then in stock"...

When I click on the link, it lists Best Buy, is that is the place you're speaking of? I have a Best Buy about 3 miles from me..

I will hit my Yellow Pages and see what I have close by before I'll take you up on that more than generous offer..

Thanks again TCJr!

<*)))>{

 

[Ice Scratcher]

FWIW, here is a picture of mine with the new switch installed...

<*)))>{

 

[TCosbyJr]

TCosbyJr,

Hey thanks a bunch for your offer, and help! I PMed you back but...

You said "the first store listed has then in stock"...

When I click on the link, it lists Best Buy, is that is the place you're speaking of? I have a Best Buy about 3 miles from me..

I will hit my Yellow Pages and see what I have close by before I'll take you up on that more than generous offer..

Thanks again TCJr!

<*)))>{

Strange Google, on my search it brings up my local electronics store, Stansifer Electronics. No sadly Best Buy doesn't have the part - or any electronic components for sale actually.

If there isn't anything useful on the Google search with your city/state then it may be there isn't anything nearby you (a common problem actually).

I'll send the part out to you today and I'll respond to your PM when it is in the mail.

Thomas

 

[Ice Scratcher]

Thomas,

I was thinking Best Buy would be the last place to have it, but thought it might be worth a shot...lol..

Radio Shack does not have it either. After calling around, the most helpful guy said nobody around here has carried that type of stuff since China took over, he did suggest Mouser as a great place to order from for anyone looking FWIW...

Thanks again for your help, and please include your address on a PM when you get a chance..

Good luck on your digs!!

<*)))>{

 

[Ice Scratcher]

Dang am I happy today! I installed the thermistor mod to my cen-tech last night.

I got a chance to field test it today and man, what a difference! It was weird not having to mess with the sensitivity pot every hole.. Started the day cold and ended up running the air conditioner in the the truck mid day. My pointer is running so consistent now.. I might never end up getting a Garrett the way it is working now...

I did notice now my weak link is the buzzer, when I nearly froze it last night while testing, it sounded very weak.. I might need to do the motor mod before winter gets here..

Thanks Ultralightpilot for being the pioneer, and thanks to TCosbyJr for the assist and all the help in sending me a couple thermistors.

Way to go guys!!

Many thanks!!

<*)))>{

 

[TCosbyJr]

Dang am I happy today! I installed the thermistor mod to my cen-tech last night.

...

Glad it all worked out for you! It really is a much needed upgrade that makes the pin pointer truly much more usable.

Your welcome, more than happy to have helped - happy hunting with your "new" pin pointer

 

[Ice Scratcher]

It really is amazing how much that little component helps!

<*)))>{

 

[luke3026]

I have a pack of those thermistors on the way. Any advice for getting it soldered to the board? It looks like a mighty tight spot to get the top of a soldering iron to. I imagine it'd be easier to do from the back of the board, but that looks to require a lot of disassembly to get at.

 

[BentRod]

I have a pack of those thermistors on the way. Any advice for getting it soldered to the board? It looks like a mighty tight spot to get the top of a soldering iron to. I imagine it'd be easier to do from the back of the board, but that looks to require a lot of disassembly to get at.

If the tip of your soldering iron is too blunt to get into tight spots, you can wrap a section of heavy gauge copper wire around the tip and leave the tag end pointing down just below the actual tip of your soldering iron. That tag end can then be sharpened and will conduct enough heat to make a suitable fine point soldering tip for small components as the copper wire will conduct enough heat to melt the solder. Helps to "tin" it first after it gets hot, just like a regular soldering iron tip. Works great in a pinch.

 

[TCosbyJr]

I have a pack of those thermistors on the way. Any advice for getting it soldered to the board? It looks like a mighty tight spot to get the top of a soldering iron to. I imagine it'd be easier to do from the back of the board, but that looks to require a lot of disassembly to get at.

No need to disassemble the pinpointer beyond removing the screws and taking the top half of the pinpointer case housing off to reach the board to begin with. The board uses solder thru holes which means you can solder on either side effectively.

For me I tinned the ends of the thermistor leads with solder (simply heat the wire leads to flow solder onto them, and I did enough to leave tiny "blobs" of solder on them), and did the same to the contact point "holes" on the board as well.

Then I align the thermistor over the holes on the PCB and bend the wire leads to ensure proper fit before soldering.

I then solder the thermistor leads starting at the end closest to the pinpointer housing / edge of the board (hardest point to solder), then solder the other lead closest to the middle of the pinpointer. While soldering it is best to ensure the thermistor leads do go into the holes a bit for a reliable connection.

Once you have it soldered, simply press the thermistor over/down some to ensure you can reassembly the housing case.

Best of luck it is a great mod/upgrade that turns a unusable summertime pinpointer into one that can be used year round no matter the temperature.

 

[luke3026]

Thanks for the advice. I used this opportunity to replace my 25-year-old 25watt Radio Shack soldering iron with a new Weller with interchangeable tips. The needle point it came with should do the job nicely.

 

[OchoTrevo]

Can someone chime in on how much wire to trim off the thermistor before soldering to the board? I'm assuming it doesn't matter as long as you can close the case but want to make sure.

Thanks,

TC

 

[Ice Scratcher]

The length of the wires is irrelevant, mine are bent at a right angle and the thermistor is over the top of other components... By doing that, it created more room to solder...

<*)))>{

 

[OchoTrevo]

Thanks for the help Scratcher!

TC

 

[OchoTrevo]

So I replaced the switch and added a thermistor. Replaced the buzzer with a motor. Have used it twice in +100 degree heat with no apparent problems.

I'm curious about the sensitivity of the pinpointer though. Having never used one I'm not sure how sensitive they are supposed to be. A penny needs to be about half an inch away from the tip before it alerts. Is this normal or should I attempt to tweak it a little to get some more range out of it?

TC

 

[Jeep Wj]

I tried the longer wire trick no go I think sometimes something gets too hot and goes out. Unless Pull tab got his to work mine pooped also, Back to beginning with another unit no biggie just like to tinker.

Thanks for all the help...

 

[HarveyH48]

So I replaced the switch and added a thermistor. Replaced the buzzer with a motor. Have used it twice in +100 degree heat with no apparent problems.

I'm curious about the sensitivity of the pinpointer though. Having never used one I'm not sure how sensitive they are supposed to be. A penny needs to be about half an inch away from the tip before it alerts. Is this normal or should I attempt to tweak it a little to get some more range out of it?

TC

Mine is about an inch, but I had to play with the little blue trimmer on the board a few times... I have the Propointer, and often 'detune' it, for less range. It did the random beep thing yesterday, first time since I got it back. Guess it needs to go back to Garrett again. It was mid 90s out, but not happy. The Centech works fine, does have issues in the heat though, but will be doing the thermistor addition soon. I pinpoint standing up with my machine, and have a fair idea how deep, and where the target should be. I plant a marker right over that spot, dig around it. Don't really need a lot of range on the pinpointer to find the prize, it just spares me from feeling around in the dirt, which can also hide some sharp, nasty things, like broken glass...

The Centech will need to have the sensitivity adjusted occasionally, it doesn't do anything automatic, like the expensive pinpointers. You get a feel for it, just like driving a manual transmission car. If the Garrett goes completely useless again, probably won't bother sending it in. The Centech works well enough. It's not as fancy, but think that just means fewer things to go wrong, and simple to fix myself, cheap enough, that replacing it isn't a problem. It's just a tool, whatever gets the job done, is a good tool...

 

[Dirtybird]

Harbor freight sunray style

Just took a whack at the sunray design with my minelab, works pretty good! The stock probe fits inside a 1/2" PVC coupler perfect. Hot glue and solder are the only two ingredients besides a phone line and an SPST switch off of a harbor freight $1 flashlight.