Close view of a green Blinky Hawk clipped to the side of an orange Keysight multimeter, the BLINKY HAWK name moulded into its housing. A second meter sits blurred behind it with its own detector glowing orange.
Patent pending · OIH Designs

Blinky Hawk - Your DMM's BFF

Your DMM has a blind spot. It can't tell you when "0V" means "Open" and when it means "Closed."
Blinky Hawk watches that blind spot and tells you instantly: connected, open lead, or live.

A pocket-sized detector that piggybacks on your meter's voltage inputs. Same probes, same workflow, no mode switching — it watches continuously and tells you with a flash and a beep.

Get notified when it ships ▶ Watch the demo
Two multimeters side by side on a countertop, each with a green Blinky Hawk attached. The left reads 0.0000 V with its detector lit green because its probes are touching; the right reads 118.5 V AC at a wall outlet with its detector lit orange.
The sales pitch

What problem does Blinky Hawk solve?

The problem: digital multimeters have a fundamental limitation. You set your meter to a voltage mode, probe two points, and read ~0 V. Is that true zero — or are you simply not connected: a floating probe, a clip that fell off, or a measurement across an isolation barrier?

Blinky Hawk tells you what “0 V” means, letting you work safer, faster.

Probe two points. Listen.

Single beep

No voltage. You didn't even have to lift your eyes.

Double beep

You have voltage (above ABS ~0.6 V). You also didn't even have to lift your eyes.

No beep

Caution. Maybe you didn't make contact? If you were expecting voltage or continuity, you may have just found your problem.

The product

What you actually get

A self-contained, rechargeable detector with stacking banana plugs. It fits any meter with standard V/COM jacks — your probes plug into the back of it, and nothing about how you work changes.

A Blinky Hawk unit lying on a countertop, the BLINKY HAWK name moulded into its green housing, with its stacking banana pins at one end, the buzzer port, the USB-C charging slot, a short red lead and a loose orange stacking banana plug beside it. Behind it a Fluke 87V reads 118.5 V AC at a wall outlet with a second unit attached, lit orange.
The unit itself — stacking banana plugs, the buzzer port, and USB-C for charging. Behind it, a second one calling out the 118 V at the outlet.
  • Three answers, not one. Open, closed, or live — shown on a colored LED and a buzzer, so it works whether or not you are looking at it.
  • It never leaves voltmeter mode. No ohmmeter circuitry exposed to a live circuit, and no pause to switch.
  • Rechargeable. USB-C, roughly 100 hours of ordinary use per charge, and zero drain when switched off.
  • A three-position switch that also gives you a 100 kΩ test load — a fast way to tell a real supply from a phantom voltage.
  • Fully configurable. Sensitivity, alert patterns, brightness, and timing are all adjustable over USB with plain text commands. No reprogramming.

A closer look

Close view of a Blinky Hawk riding on the upper edge of a yellow Fluke 87V. The meter reads 119.4 V AC and the small round indicator on the detector is lit orange.
It rides on the side of the meter, out of the way of the display and the dial — and the same unit moves to whichever meter you are using.
A Blinky Hawk standing on end on a countertop, the BLINKY HAWK name moulded into its green housing, with the metal toggle switch on top and an orange stacking banana plug and red lead at its base.
Small and compact.
The back of a Blinky Hawk, showing the black hook-and-loop pad that sticks it to a meter, and the stacking banana pins with an orange stacking plug pushed onto them.
Rear view — hook-and-loop on the back to attach it to your meter.

Open by design

This is the whole circuit — not a redacted block diagram. The schematic and the firmware source are published, so you can see exactly what is across your probes, and change it if you want to.

Blinky Hawk V3 schematic: two 500 kilohm resistor ladders from the probe inputs meeting at a 100 kilohm sense resistor and an AO3400A bridge MOSFET, a TL431 reference, Schottky clamp diodes, an SK6812 LED, a buzzer across D8 and D9, and a pin-function table.
The V3 board in full. The two 500 kΩ ladders and the 100 kΩ sense resistor are the 1.1 MΩ your probes see; Q1 is the bridge MOSFET the detection depends on.

At a glance

FitsAny meter with standard banana V/COM jacks — stacking plugs, probes go in the back
Tells youOpen leads / closed leads / voltage present, continuously
AlertsRGB LED and buzzer, both configurable (and both defeatable)
Working rangeDetection verified from 0 V through ±1 kV
Effect on your reading−5 mV of ghost voltage on open leads; nothing once a real voltage is present
Battery320 mAh internal lithium, USB-C charging, ~100 hours per charge
OpenFirmware source and schematics published in the project repo
Off means offThe switch disconnects the battery and both leads — your meter reads exactly as it would bare
ConfigurationStored on-board, adjustable over USB serial or the desktop app
Read the user guide Quick-start sheet (PDF) How it works →
Why it's different

Not “Smart Mode.” It never switches modes.

Some DMMs — or scripted bench meters — auto-switch to ohmmeter circuitry after a 0 V reading. That's just the user changing modes, automatically. The distinction here is fundamental, not incremental: it never leaves voltmeter mode at all.

 “Smart Mode” auto-switchThis design
SpeedPauses to switch modesContinuity checked at 20 Hz (up to ~500 Hz)
ExposureCan expose ohmmeter circuitry to live voltageNever leaves voltmeter mode — nothing fragile exposed
AdoptionBuy a whole new DMMStandalone — clip it onto the meter you already love
The payoff

What “0 V” can finally mean

Across the everyday things you probe, a normal meter gives you one ambiguous number. This gives you an answer.

Probes separated byNormal meterThis detector
Copper — same net0 V“Leads Closed”
Air gap0 V“Open Leads”
Open relay0 V“Open Leads”
Diode (unenergized)0 VFunction of polarity / type
Transformer pri↔sec (unenergized)0 Vmay read “Closed” (reactive coupling) *
Capacitor0 Vreads “Closed” while charging *
GPIO pin, output low0 V“Leads Closed”
GPIO pin, MCU off0 V“Open Leads”
Energized impedanceVoltageVoltage

* It measures impedance to a fast pulse, not pure DC continuity — so reactive parts can read “Closed” even with no galvanic path.

One honest limitation. Blinky Hawk detects a low-impedance path to a fast injected transient — which, the vast majority of the time, is a genuine wire-to-wire connection. Reactive components are the exception. A capacitor passes the transient and reads like a short that climbs as it charges (short → tens of kΩ → settling around 100 kΩ), so it can trip “Closed.” A transformer, winding-to-winding, couples that transient through its interwinding capacitance: one tested unit read >4 GΩ on a megohmmeter (galvanically wide open) yet still presented a low-impedance path and read “Closed.” So near reactive parts, treat a “Closed” as “low-impedance path,” not “guaranteed DC connection.”

A Fluke 87V propped on a countertop with its probes in a wall outlet, reading 119.4 V AC. The Blinky Hawk clipped to its side is lit orange.
Live is never ambiguous — the detector calls it before you read the display.
A small child kneeling on a rug, holding both multimeter probes onto a battery holder. The attached Blinky Hawk is lit orange to show voltage is present.
Simple enough for even little kids.
Under the hood

One MOSFET, one bridge, one transient

Blinky Hawk breaks a biased divider for an instant and watches how the node settles. The decay rate is the impedance between your probes — which is how it answers the question without ever becoming an ohmmeter.

The full engineering write-up has the circuit, the measured decay curves across every decade from 10 kΩ to open, the injected-signal safety numbers, the two hardware builds, and the open questions I am still chewing on.

Read how it works
Documentation

Everything that ships with it

Start here

Quick-start sheet

The one-page insert that comes in the box: hookup, the switch, what the lights mean, and the safety notes. Printable PDF.

Everyday use

User guide

Hookup, indicators, interpreting results, the 100 kΩ test load, battery and charging, safety, and troubleshooting.

Going deeper

Firmware manual

Every configuration key, the serial command reference, the low-power mode, and worked recipes for retuning a unit.

Make it your own

Source & schematics

The firmware source and the board schematics are published in the project repo, so the unit is completely customizable — change the behavior over USB, or change the code and reflash it yourself.

See it in action

Two minutes on the bench

Open leads, a real connection, and a live circuit — and what the meter shows in each case.

Stay in the loop

Want to know when Blinky Hawk is available to order?

Drop your email below and I'll let you know the moment it's ready.