Jump to content

Recommended Posts

Has someone verified that sample timing stays constant with battery voltage change? On lesser pi’s it moves.

Share this post


Link to post
Share on other sites

I've never checked mine, but find that interesting. Mine was built in '13. Do you have a diagram for the coil connector? I'd like to check mine. Something's fishy, for sure, as the voltage clearly makes a big difference. It's possible, because the voltage pulses at 100kh, that you can't read the voltage difference, except with a synchroscope, or other similar device.

Jim

  • Like 1

Share this post


Link to post
Share on other sites
20 minutes ago, Jim in Idaho said:

I've never checked mine, but find that interesting. Mine was built in '13. Do you have a diagram for the coil connector? I'd like to check mine. Something's fishy, for sure, as the voltage clearly makes a big difference. It's possible, because the voltage pulses at 100kh, that you can't read the voltage difference, except with a synchroscope, or other similar device.

Jim

Yep so was mine a 2013 Jim,  I don't know how digger bob got is to see his tiny test pieces in that video but mine wouldn't see them, It ran as smooth as silk even with a thunder storm going on right about the house Nothing phased my TDI SL, all it took was a minute tweak of the Tune knob and it was good as gold,  My 3500 didn't like storms 100 to 200 miles away but the SL has the best threshold ever put in a detector.:wub: 

Share this post


Link to post
Share on other sites

I used a calibrated, Fluke TRUE RMS volt meter for my measurements.

Share this post


Link to post
Share on other sites
1 hour ago, Mark Gillespie said:

I used a calibrated, Fluke TRUE RMS volt meter for my measurements.

I think, to use a voltmeter, you'd have to put a capacitor across the connections to get a true reading. I'm not sure about the capacitance needed...maybe 5mfd?

Jim

Share this post


Link to post
Share on other sites
3 hours ago, auminesweeper said:

Yep so was mine a 2013 Jim,  I don't know how digger bob got is to see his tiny test pieces in that video but mine wouldn't see them, It ran as smooth as silk even with a thunder storm going on right about the house Nothing phased my TDI SL, all it took was a minute tweak of the Tune knob and it was good as gold,  My 3500 didn't like storms 100 to 200 miles away but the SL has the best threshold ever put in a detector.:wub: 

With the 12"DF,  and 16.8 v battery, mine will easily see a 1 grain gold bar at 3" in an air test, John.  Might do even better with my NF 8x6 Sadie, but I haven't tested that coil.

Jim

Share this post


Link to post
Share on other sites
2 hours ago, Jim in Idaho said:

With the 12"DF,  and 16.8 v battery, mine will easily see a 1 grain gold bar at 3" in an air test, John.  Might do even better with my NF 8x6 Sadie, but I haven't tested that coil.

Jim

Well Jim mine would not see an 0.17 gram bit which is equal to just over 3 Grains with the 12" DF coil or the 7.5 DF coil not even with it sitting on the coil, regardless of the battery voltage.

  • Like 1

Share this post


Link to post
Share on other sites

I just tested the voltage output on mine, and it tracks perfectly with the battery pack voltage. With the 4 cell pack at 14.53v, I got 6.29v of output to the coil, and with the 3cell pack at 12.03v, I got 5.3v of output. So the higher battery voltage does push more current through the coil on mine. Thus a stronger magnetic pulse going into the ground. I figured out the correct terminals by using my inductance meter to see which terminals showed a coil across them. Looking at the connector, with the gap at the bottom, the correct terminals are the second from the left, and the second from the right.

 Inductance on both the NF Sadie 8 x 6, and the Super Pulse 350 14 x 9 showed 1.4 micro-henrys.

Jim

  • Like 1

Share this post


Link to post
Share on other sites
10 hours ago, Jim in Idaho said:

I just tested the voltage output on mine, and it tracks perfectly with the battery pack voltage. With the 4 cell pack at 14.53v, I got 6.29v of output to the coil, and with the 3cell pack at 12.03v, I got 5.3v of output. So the higher battery voltage does push more current through the coil on mine. Thus a stronger magnetic pulse going into the ground. I figured out the correct terminals by using my inductance meter to see which terminals showed a coil across them. Looking at the connector, with the gap at the bottom, the correct terminals are the second from the left, and the second from the right.

 Inductance on both the NF Sadie 8 x 6, and the Super Pulse 350 14 x 9 showed 1.4 micro-henrys.

Jim

Very interesting Jim. 

What device are you using to measure the voltage? 

I was using a calibrated Fluke True RMS and was measuring directly from the TX output on the board.

All this said I noticed a very large difference in voltage from a complete counter clockwise frequency offset to a complete clockwise setting.  Even though there was a large difference in output voltage I didn't see any extra air test advantage.  The manual states this feature function is "This control makes small adjustments to the transmitter pulse rate".  I was guessing a small shift in the frequencies and wasn't expecting the voltage span.

Now you have me to wondering if the inductance of my coils might be different than yours because if the inductance is quite a bit larger (value) that would limit the current flow considerably.

 

Share this post


Link to post
Share on other sites

I'm measuring mine with a digital multimeter set on A/C volts. On the frequency, I'm seeing, with the 14.5v pack, 6.05v on the low, and 6.54 on the high. MIddle was 6.29.

 I'd be surprised if your coils have much difference in inductance, but it's possible.

EDIT:   I just did the inductance test on the 12"DF and got the exact same reading of 1.4 microhenrys. I assume that is the design inductance for the coils for TDI's. and probably the other brands of PI's. But, I don't know this to be fact.

Jim

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By Steve Herschbach
      I have never experienced this on any version of the TDI. The “ground balance off” mode should be the pure unfiltered signal. Engaging the ground balance engages a filter which reduces the air test results in a properly functioning TDI. The only reason the TDI has the ability to turn off the ground balance is to get this extra depth back, as has been highlighted in numerous online posts and videos. The manual says air test depth increases with the ground balance shut off. What you are saying simply makes no sense from a pure electronics standpoint and how the ground balance functions. If a TDI loses depth in air tests when the ground balance is shut off then in my opinion it is not working properly.
       
    • By GB_Amateur
      At one time I bookmarked or downloaded photo and text instructions on modifying the TDI/SPP to effectively turn it into a TDI/SL.  I can't seem to find it.  Anyone here know the link(s)?
       
    • By Jim in ma
      I have had my TDI BH for 2 months now and was wondering if a mono coil would get more depth and less sensitivity to small targets namely lead bullets than the stock Dual Field.  Where I hunt there are a lot and they sound good but fall through the holes in my scoop { 10 mm} 
       

    • By FWest
      I just purchased a TDI SL special edition. The unit came with the Miner John  8x12". It seems to do OK at the beach but leaves me wondering if another coil could do better.  Not overly concerned about finding all the tiny bits. Also I find the walking pace when using the 12" mono, for complete coverage, is a challenge for me on the beach.
       
    • By bamajoe
      Have been reading past treads from Steve H., Reg Snift, and others concerning modification that could be added to the TDI, TDI PRO, and TDI SL. One was a Li ion battery pack to up the voltage. I can do that. Another was to change a couple caps (c20 and c21) to .22 mf and change a couple op amps. Sounded like Reg would do some for a price. Then sounded like Reid Mann in Virginia would do them. Then the VP from Whites came on the forum asking for feedback. I forget his name but think he just retired , anyway, his final answer sounded like he would have this mod. incorporated into the new TDI SL future production. This was a year or two back. Now my question, Do you know if this mod. has been installed in the new TDI SL that fedex is supposed to deliver to me tomorrow? If not since I'm a retired electronic tech. I could install myself if Reg had given a little more information. If no one has or are willing to give out, do you know anyone that installs the mod. for a price? Thanks, Joe
    • By Gerry Freeman-Smith
      Has anyone else that’s using the supplied hip/chest mount pouch had issues with it splitting. 
      My first one started within days and Whites sent me a replacement. First time out yesterday with the new one and it’s spliitting by the netting. 
      Its not the design or the stitching, it’s the poor quality material used. 
      They really should’ve used terylene or something stronger



×
×
  • Create New...