Learning to read a metal detector for the first time can present some challenges. Understanding the various tones can feel like learning a completely different language. Thankfully, it’s relatively easy to read a metal detector once you have experience listening to the tones.
Metal detectors have different systems, but you’ll need to understand the tones and read the visual discrimination indicator (VDI). These features provide information on the coins detected. It comes down to the tones and one small gauge for older analog models.
This guide will cover all the details of how to read a metal detector. Whether you’re a beginner in metal detecting or a certified expert looking for a new way to teach others, this guide is for you.
1. Get To Know Your Metal Detector
Metal detectors are pretty popular nowadays. I won’t say everyone has one, but they’re no longer a rarity. As the popularity of these instruments has increased, so has the diversity. There’s a huge variety of metal detectors.
Let’s look at some of the most common that you’ll find:
Very Low Frequency (VLF) Metal Detectors
VLF detectors are the original metal detectors. Because of this, they are also the most popular type. VLF detectors work with two coils.
- The transmitter
- The receiver
The transmitter sends electrical currents deep into the ground in search of a magnetic field — always created by metal. The receiver then detects the response and lets you know what it finds through the display.
VLF metal detectors are typically cheaper, easier to use, and lighter than many of their counterparts.
Multi-Frequency Metal Detectors
Unlike VLF detectors, multi-frequency detectors operate with multiple frequencies at the same time. What this means is that you can detect multiple items at varying depths at the same time.
These metal detectors differ from selectable frequency detectors, which don’t allow you to use multiple frequencies simultaneously. Instead, these detectors provide multiple frequencies that you must use individually.
Pulse Induction (PI) Metal Detectors
Pulse Induction metal detectors work differently than both VLF and multi-frequency detectors. The previous ones we’ve discussed use two separate coils to transmit and receive signals. The PI detector is different in that it only uses one coil. This single coil does both the transmitting and receiving.
This type of detector works by sending out rapid pulses repeatedly. As the signals reflect, the device detects how long it took between the sent and the received signals. A longer time between the two tells you that the device has found metal, whereas a shorter time indicates that the device should continue looking.
It is from these three that all other metal detectors come.
Most other metal detectors fall under the multi-frequency detector category. For example, this category also contains gold and waterproof metal detectors.
You can find both analog and digital detectors in VLF form, but all PI and multi-frequency metal detectors are typically digital.
With all this in mind, the first step is to know what type of metal detector you’ve chosen to purchase. If you still need to purchase one, this is a great time to research each one. The type of detector you have determines how to read it.
2. Understand the Tones
All metal detectors, no matter how advanced, operate with the use of various tones. Learning what these tones sound like is the challenge since each metal detector will sound a bit different, depending on what type of metal detector it is and who the manufacturer is.
Metal detectors provide different tones to identify different metals. When you move the detector over the ground, you’ll notice that it begins to beep. These initial tones let you know that the detector is doing its job.
Once the detector has found something, you’ll notice that the pitch of the sound changes. Usually, the pitch will rise higher when the detector has found a piece of metal. However, different metals will produce different tones.
Playing around with coins is a good way to get to know your metal detector’s tones. Coins are a good starting point because they produce distinct and high-pitched sounds. This practice will get you used to how the detector sounds when it encounters metal.
Different metals have different tones, and it will take some practice to get to the point where you can gauge what metal it’s detecting from the surface. In general, however, higher pitches are an indication of higher-value metals.
Let’s talk about some examples.
- Trash: Trash typically produces a low, distinctly broken sound. The sound may come in and out since trash contains metal intermixed with other trash materials.
- Junk Materials/Metals: Depending on the types of metals intermixed, the sound may change pitch regularly. In general, however, the junk will produce a sound similar to trash — low and broken. The difference is that the tones will be more consistent.
- Silver: Usually, silver will make a distinct, high-pitched sound.
- Gold: Gold will typically make a high-pitched sound, as well. It is usually lower than silver, however.
- Brass & Bronze: These metals typically have a medium-pitched tone. It isn’t as low as junk materials but isn’t as high as more quality metals such as silver and gold.
Learning your metal detector’s tones is critical to reading the device. There is a learning curve to it, however.
There will be a process of trial and error to learn what each tone means. Most of this process will be digging up various metals during the discovery process because, ultimately, this is the only way you’ll know for sure what metal the device has detected.
One thing that you can do to help you learn the tones better is to use the proper technique when searching. The gridding technique is the easiest way to learn the tones because you’ll hear the same tone repeatedly.
3. Reading the Visual Discrimination Indicator
If the tones are the most important part of reading a metal detector, understanding the visual discrimination indicator comes second. This indicator is part of the visual display on the metal detector and contains numbers ranging from 0 to 100.
The various numbers indicate that you’ve struck upon specific metals. While useful, the VDI isn’t quite as accurate as using the tones. For this reason, it’s best to read this in conjunction with the tones once you fully understand each tone.
While metal detectors have varying number charts, in general, the lowest and highest metals are the same. Iron is typically the lowest on the scale, and high-quality gold is the highest.
The in-between numbers can indicate a range of various metals. No set number always indicates a specific metal, but having a rough guide is still useful.
Let’s take a look at what each of the numbers usually means.
- 0: 0 is the lowest number on the visual discrimination scale. Almost always, this number is an indicator of iron in the soil. You may notice this consistently as you sweep your metal detector since many soils contain iron scattered throughout the dirt.
- 1-8: Anywhere between 1 and 8 typically indicates very low-quality metals. These metals likely aren’t worth digging up.
- 8 – 25: These metals are typically a bit higher quality. One of the main metals you may encounter in this range is nickel.
- 25 – 34: Usually, this indicates high-quality nickel. You may find a nickel coin, for example.
- 35 – 44: This is typically an indicator of a lower-quality form of gold.
- 45 – 50: These numbers usually indicate that you’ve struck upon higher-quality silver.
- 51 -70: This is a wider range of numbers that usually indicates you’ve struck upon higher-quality gold.
- 70-100: These numbers can indicate multiple metals, but all of them will be very high quality. You will likely discover silver or gold.
The discrimination scale looks a bit different from detector to detector. That said, the number scale I’ve presented today is only a rough estimate of what you might expect to see on any given detector.
Different models and brands have their own numbered scale, so it may differ slightly from the one presented here. Regardless of which brand you purchase, it’ll likely come with an instruction manual. Always check the manual for an accurate idea of the VDI numbers.
The visual discrimination indicator is most useful when looking for coins. Because nearly all coins create a similar tone, it can be challenging to determine what coin you’ve found. A glance at the VDI can help determine whether the coin is worth digging up.
The VDI is helpful when you are looking for specific metals. Apart from this, it’s best to learn the tones and combine that with the indication on the VDI.
Final Thoughts
The key to reading a metal detector is learning to understand the various tones that the device presents. Usually, lower tones indicate a lower-quality metal and visa-versa.
The VDI is useful to use in conjunction with understanding tones. Using a VDI alone isn’t recommended because the indications change with different models or brands. Plus, it’s not as accurate as the tones.
While learning to read a metal detector can take time, it’s always useful if you have a hobby of collecting old coins. Metal detectors are invaluable in finding worthy coins.
