TDI SL White’s Electronics, Inc. Sweet Home, Oregon USA Building the World’s Finest metal detectors for over 60 years.
TDI SL Owner’s Manual CONTENTS Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Batteries and Charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 QuickStart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Principles of Pulse Induction . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Controls Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Power/gain . . . . . .
TDI SL Owner’s Manual Assembly Search coil Lower rod Arm cup Rubber washers (2), fiber bolt Clevis Cam lock Battery door 1. Remove all parts from the shipping carton and check assembly diagram to ensure all parts are present. 2. Install black rubber washers on fiber clevis/lower rod, insert clevis lower rod onto loop ears. Use only nonmetallic washers, fiber bolt, and fiber thumb nut to secure loop/search coil to clevis/lower fiber rod. 3.
TDI SL Owner’s Manual the floor. If the instrument fit feels uncomfortable, readjust clevis/lower rod length with spring clip button and camlock so that search coil can be held near the floor without stooping over. 6. Remove the protective paper from the two black arm cup foam pads. Carefully align pads on the inside of the elbow cup, one on each side of the center rod, and press firmly into place. 7.
TDI SL Owner’s Manual Batteries and Charger The TDI-SL includes a rechargeable NiMH battery pack as the primary power source, and a standard alkaline battery pack as a backup. Fully charged, they supply a nominal 12 volts (the NiMH may be slightly less) and will power the TDI-SL for about 4-5 hours. The TDI will operate until the batteries drop to about 8.5 volts, at which point the low battery LED will turn on. A drop-in charging cradle (Part Number 509-0036) is used for recharging the NiMH battery.
TDI SL Owner’s Manual QuickStart 1. Set the Conductivity switch to ALL. 2. Set the Frequency offset to the midpoint. 3. Set the Ground Balance to ~8. 4. Turn on the power and adjust the Gain to “2.” 5. Adjust the Threshold to achieve a faint background hum. 6. With the coil on the ground (no motion) increase the Gain until the audio begins to chatter. Back off slightly for a reasonably smooth threshold. 7. Optional: adjust the Frequency offset to minimize the amount of chatter. 8.
TDI SL Owner’s Manual Principles of Pulse Induction Pulse induction (PI) detectors are very different from traditional induction-balance (VLF) designs. Instead of transmitting a continuous-wave magnetic field, the PI detector periodically transmits brief impulses of magnetic energy. The PI receiver then looks at the impulse decay for target (and ground) information.
TDI SL Owner’s Manual out other minor trash targets at the expense of eliminating potentially good targets such as jewelry, but this method is very limited in the range of trash targets that are rejected. Furthermore, the ground balancing method used by TDI has a side affect with target responses. Target conductivities below the ground balance point produce a positive response for which TDI assigns a high tone. These targets are generally low conductive such as small nuggets, jewelry, and small iron.
TDI SL Owner’s Manual Controls Threshold The Threshold control sets the level at which the background audio tone is heard. In most cases, faint target signals are easiest to hear when the threshold is set to a low but clearly audible level. A higher threshold level can result in audio fatigue. Too low of a threshold level means that a stronger target signal is required to produce an audible change. Threshold is best determined at a low gain setting where there is no chatter.
TDI SL Owner’s Manual that higher gain will always give better depth. In air tests this is generally true, but ground results can depend on the amount and type of mineralization. With the coil on the ground, increase the gain until the detector exhibits chatter, then back off slightly for a reasonably steady threshold tone. Use the Frequency offset control to help deal with EMI-related chatter, and proper ground balancing will minimize chatter due to mineralization.
TDI SL Owner’s Manual Pulse Delay affects the ground balance point, so whenever the delay is changed the ground balance should also be checked and re-adjusted. Higher pulse delays require a lower ground balance setting. Target Conductivity The Target Conductivity switch allows you to select between high-only, low-only, or all target responses (see the Principles of Pulse Induction section for details). There are two caveats with this switch.
TDI SL Owner’s Manual Ground Balance This control is used to balance out the signal from ground mineralization. There is an OFF position for which TDI runs in straight PI mode with no ground balance. To ground balance TDI the Target Conductivity control must be set to ALL in order to hear both conductivity tones. Set the Gain to about the mid-point or until the audio just begins to chatter.
TDI SL Owner’s Manual Frequency This control makes small adjustments to the transmitter pulse rate. This is used to counteract any interference which might be due to outside electromagnetic sources, such as radio stations, microwave, short wave, electric fences, power lines, lightening, electrical storms, or other metal detectors being used nearby. This interference is recognized by a warbling or repetitive pulsing of the audio threshold, and can mask target signals.
TDI SL Owner’s Manual TDI In Depth Ground Balancing One of the key features of TDI is its ability to balance out ground mineralization while maintaining pulse induction depths. This is achieved using a differential technique whereby two decay samples are compared; the Ground Balance control is adjusted until the two samples have the same response, thereby canceling the ground signal.
TDI SL Owner’s Manual With Ground Balance = On and Conductivity Mode = All, all targets will give an audio response, either a high or low tone. New users are encouraged to use this setup and practice with various targets to learn their audio responses. A US nickel or small gold nugget works well for a low conductive target, and a US quarter makes a good high conductive target. TDI is a motion detector, so target responses depend on the motion of the coil.
TDI SL Owner’s Manual Setting the Target Conductivity to either Low or High will cut out half of the response, as shown in the next diagrams. The Target Conductivity = LOW Target Conductivity = HIGH noise, which tends to be equally distributed between the high and low tones, is cut in half. However, you also lose one of the conductivities. If you know you primarily want to hunt small to medium nuggets or fine jewelry, then you will not lose much running in the Low mode.
TDI SL Owner’s Manual A lower threshold makes the TDI quieter and less chattery but also requires a stronger target signal to produce a tonal response: A lower threshold can be played off against a higher Gain setting, although you may find that the net outcome is about the same.
TDI SL Owner’s Manual ence. Sub-gram gold nuggets are often only detectable at the lowest delay setting while larger nuggets, even of the same alloy, can be detected at higher delay settings. This is largely due to skin effect, whereby the response of small thin targets dissipates quickly. A good exercise is to experiment with different targets at different Pulse Delay settings.
TDI SL Owner’s Manual literally gives you two different size coils running simultaneously: a larger outer coil for large target depth, and a smaller inner coil for small target sensitivity. As such, even the 12” DF coil, with its 6” inner coil, can pick up nuggets of only a few grains. The 7” DF coil, with its 3.5” inner coil, is even better at picking up grain-sized nuggets, with little compromise on large target depth.
TDI SL Owner’s Manual Besides overlapping each sweep, it is important to keep the coil close and parallel to the ground. Pendulum-swinging the coil results in loss of depth, and if the ground balance isn’t perfectly set the variation in loop height will create a ground response. The following illustration shows improper and proper coil sweep motion. Wrong Right Dealing with Noise Because PI detectors have wideband receivers they are more prone to noise and interference than narrowband VLF designs.
TDI SL Owner’s Manual detectors due to the overwhelming number of EMI sources. If you cannot minimize noise with the Frequency control, then turning down the Gain or Threshold is your best bet. Excessive chatter will easily mask targets, plus results in audio fatigue. It is better to trade off sensitivity for smooth audio so you can hear the targets.
TDI SL Owner’s Manual TDI-SL Specifications Operating mode . . . . . . . . . . . . . . . . . . . . . . . . Pulse Induction Pulse Frequency . . . . . . . . . . . . . . . . . . . . . . . . 2.6kHz - 3kHz Pulse Delay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10s - 25s Search modes . . . . . . . . . . . . . . . . . . PI, Ground balanced PI Ground balance . . . . . . . . . . . . . . . . . . . . . . .Differential delay Audio tones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TDI SL Owner’s Manual Warranty If within two years (24 months) from the original date of purchase, your White’s detector fails due to defects in either material or workmanship, White’s will repair or replace at its option, all necessary parts without charge for parts or labor. Simply return the complete detector to the Dealer where you purchased it, or to your nearest Authorized Service Center. The unit must be accompanied by a detailed explanation of the symptoms of the failure.
TDI SL Owner’s Manual TDI SL Treasure Hunter’s Code of Ethics 1. Always check federal, state, county, and local laws before searching. 2. Always obtain the owner’s permission before accessing private property. 3. Take care to refill all holes and leave no trace. 4. Remove and dispose of any and all trash and litter found. 5. Whenever possible, return identifiable property to its rightful owner. 6. Never destroy historical or archaeological treasures. 7.
