There’s something captivating about building your own electronic devices from the ground up. The way components come together—each serving a specific role like a musician in a band—forms the beating heart of countless projects. But some components inspire more than others. Some spark not just ideas, but ambition. The VHF15-16IO5 is one of those. It’s not your typical, easy-to-understand part like a resistor or a standard transistor. This component is a high-frequency diode module, often used in fast-switching circuits and specialized power control systems. At first glance, it might seem like an odd choice for a DIY project. But that’s what makes it interesting.
Today’s journey revolves around building a high-frequency proximity and motion sensing array using the VHF15-16IO5. The goal is simple: we’re going to create a sensor module that reacts to the movement or presence of objects, using high-frequency electromagnetic behavior—not ultrasonic pings or infrared beams. Instead of simply copying existing solutions, we’re going to tap into a more industrial flavor of sensing, where switching speeds and signal cleanliness are critical.

Getting to Know the Heart: VHF15-16IO5

Before diving in, let’s touch base with the star of the show. The VHF15-16IO5 is not a beginner’s diode. It’s a high-speed, high-voltage module diode, designed to handle fast, sharp switching in applications that need rapid energy conversion. Think power supplies, industrial drives, or RF equipment. It’s built for environments where milliseconds matter and where traditional diodes would struggle to keep up.
But what makes it especially suitable for our project is its ability to work in systems where the signal must be clean, precise, and immediate. That means it’s perfect for high-frequency sensing applications—especially when combined with inductive or capacitive proximity sensing.
Our plan is to use it to detect subtle shifts in electromagnetic fields caused by nearby objects, and to switch output signals cleanly without lag. The VHF15-16IO5 will act as the switch in a sensing circuit that’s triggered not by touch or pressure, but by proximity—turning invisible signals into actionable triggers.

The Vision: A Sensing Array That Feels the Air

Imagine a board that doesn’t just detect that something is nearby—it knows something is moving past. Something metallic. Something that disturbs the clean rhythm of a high-frequency circuit. That’s what this project is about.
You’ve seen motion sensors in lights and alarm systems. They use PIR (passive infrared), which detect changes in heat patterns. But we’re going a different route. Instead of detecting heat, we’ll be detecting high-frequency field disruption. The sensor board will be able to recognize when something gets close to it, thanks to the way metal objects affect the behavior of an inductive loop. This means it could be used in places where PIR wouldn’t work well—like inside machinery, or in high-temperature environments.
The final device will be a small rectangular board with a cluster of three sensing zones, each using its own VHF15-16IO5 module, and feeding into a central controller that can interpret the signals and activate responses—like lighting up an LED, triggering a relay, or sounding an alarm.

Step One: Designing the Sensor Nodes

At the heart of each node is an inductive loop—just a few turns of wire placed near the surface of the board. These loops form part of an oscillating circuit. When something metallic approaches the loop, it affects the oscillation, essentially damping or altering it. That’s where the VHF15-16IO5 comes in. Positioned at the switching output of each loop circuit, it ensures that only clean, fast signals are passed forward. Without it, noise and slow decay could introduce false readings or missed detections.
Each loop is tuned to a slightly different frequency, to minimize cross-interference and allow the system to “see” different zones independently. The VHF15-16IO5 helps isolate each loop’s behavior, acting like a disciplined gatekeeper—only letting precise, intentional changes pass.
The result? When someone walks past, you don’t just get a generic “motion detected.” You get a timeline. The system knows which sensor fired first, which fired second, and how long between them. That opens the door to gesture control, direction sensing, and complex automation.

Step Two: Building the Board

With the concept clear, it’s time to get our hands dirty. The PCB for this project is fairly compact—around the size of a large smartphone. It holds three sensor loops on the top layer, with traces leading into compact circuits built around each VHF15-16IO5 module.
Each sensing zone consists of a few key parts: the inductive loop, a fast oscillator circuit, a signal conditioning section, and the VHF15-16IO5 acting as the output gate. When the loop’s frequency is altered by an approaching object, the change is recognized by the circuit and the diode switches state—allowing a clean, sharp signal to pulse forward.
We route all three outputs into a small microcontroller—not to process heavy logic, but just to act as a hub. It reads the order and timing of the signals and lights up indicators, sounds a buzzer, or sends a signal to an external system.
The beauty of this design lies in its responsiveness. Unlike more sluggish sensors that rely on averaging and delay to avoid false positives, this setup is immediate. You move your hand near it, and the LEDs flash like a ripple across water.

Step Three: Testing and Tuning

The real magic of this project happens during testing. With the board assembled, each sensor is tuned by adjusting the frequency of its oscillator circuit. We want them close enough in behavior to respond to the same objects, but separated just enough to avoid overlap.
Wave your hand near the left sensor, and only that one fires. Move to the center, and you get a clean response. Now sweep from left to right—and you see the sequence light up: left, center, right.
This is where the high-speed switching of the VHF15-16IO5 really shines. There’s no delay, no bounce, no confusion. The signals are crisp. And because the diode can handle the demands of high-frequency switching without heat buildup or drift, the system remains stable even after hours of continuous operation.
This stability is crucial if you’re planning to use this array in a factory environment or inside an interactive display. You can leave it running all day and it’ll just keep responding, like a silent sentry.

Step Four: Enclosure and Real-World Use

With the electronics working, it’s time to house the device. The final enclosure is made of plastic, with cutouts allowing the inductive loops to sit flush near the outer shell. That way, the signals aren’t blocked or distorted. We mount it to a test rig that lets objects pass in front of the sensors, simulating conveyor belts or walking paths.
In practical use, this device could do a lot:
●  In a smart home, it could detect gestures to turn lights on and off—wave left to turn off the light, wave right to turn it back on.
●  In industrial machinery, it could act as a safety system—detecting when an operator’s hand gets too close to a hazardous part and shutting things down.
●  In retail displays, it could trigger screens or lights when a customer approaches, or even count how many people walk past and in which direction.
●  Even in public art installations, it could be used to trigger lights or sounds based on audience movement.
What makes this project special isn’t just what it does—it’s how it does it. Cleanly, quickly, and elegantly, using the kind of industrial-grade component that rarely gets DIY attention.

Why It Matters

Too often, DIY projects focus on what’s accessible or easy. And that’s fine. But there’s a deep satisfaction in using parts that were never meant for your workshop bench—in taking something meant for high-frequency industrial power systems and turning it into a gesture sensor you can use at home.
The VHF15-16IO5 isn’t a flashy component. It’s not programmable, it doesn’t light up, and it doesn’t come with a friendly tutorial. But what it does offer is precision, speed, and reliability. And when you build a project around that kind of foundation, you end up with a device that feels different—more confident, more capable.
This sensor array project is just the beginning. Once you’ve got the hang of using high-frequency diodes like the VHF15-16IO5, you start to see other opportunities: high-speed data logging, reactive circuits, timing-critical switching. The limits aren’t technical—they’re imaginative.
So if you’ve got one of these strange, powerful modules lying around, don’t just leave it in a drawer. Put it to work. Let it switch. Let it sing. Let it become something new.
And if you do, you might just find that your workshop gets a little quieter—but your circuits get a lot sharper.