3mm Round Top Fast Flashing 2Hz LED

3mm fast-flashing LEDs (2Hz) blink twice per second in the compact T-1 package — two complete on-off cycles every 1,000 milliseconds.

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3mm fast-flashing LEDs (2Hz) blink twice per second in the compact T-1 package — two complete on-off cycles every 1,000 milliseconds. The built-in integrated circuit (IC) produces this faster-than-standard cadence automatically, with no external timer or microcontroller. The 2Hz rate is noticeably more urgent than the calm 1Hz crossing-signal blink, making it the go-to choice for attention-demanding safety markers, bicycle visibility lights, and warning indicators in the 3mm form factor. At just 3mm across the lens, these LEDs fit where 5mm LEDs will not: inside HO and N scale model structures, compact guitar pedal enclosures with 3mm bezels, tight wargaming terrain builds, and miniature electronic panels with limited real estate.

Safety markers and bicycle visibility: Nighttime cyclists and pedestrians mount 3mm 2Hz LEDs in compact clip-on housings, wristbands, and shoe attachments for enhanced intersection visibility. The double-blink cadence is clinically shown to be more attention-grabbing to drivers than a single slow blink. The 3mm body fits inside small weatherproof housings that clip onto helmet vents, strap buckles, and spoke nipples without adding noticeable weight. Red 3mm 2Hz LEDs are standard for rear-facing visibility; amber for side-facing; white for forward-facing reflectors. The ~50% duty cycle extends battery life to roughly twice that of a continuously lit LED, allowing multi-night use from a single coin cell. Kayakers and paddleboarders mount green 3mm 2Hz LEDs on PFD zippers for low-profile nighttime water visibility.

Scale modeling and miniature builds: Model builders use 3mm 2Hz LEDs wherever a faster blink conveys urgency at scale. Construction site dioramas use amber 3mm 2Hz LEDs on barricade props and crane boom tips. Airport diorama builders mount red 3mm 2Hz LEDs on runway threshold markers and taxiway hold-short indicators. Emergency vehicle models in HO scale (1:87) use red and blue 3mm 2Hz LEDs for light bar simulation where the faster cadence better matches the perceived speed of real emergency strobes at miniature scale. Harbor and marina dioramas use red 3mm 2Hz LEDs on channel buoys and pier warning markers. The 3mm body fits scale signal housings and vehicle cavities without modification, unlike a 5mm LED which often requires trimming.

Electronic panels and indicator circuits: DIY electronics builders use 3mm 2Hz LEDs as fault indicators on custom circuit boards, sensor modules, and breakout boards where a blinking LED signals an error condition more urgently than a slow 1Hz blink. Ham radio operators mount amber 3mm 2Hz LEDs as high-SWR warning lights on compact QRP rigs and antenna tuners. Security alarm panels use red 3mm 2Hz LEDs behind small indicator windows as zone-violation alerts. Laboratory and test equipment builders wire 3mm 2Hz LEDs into custom probe housings and measurement rigs as rapid-flash continuity testers.

Available colors and specifications: We stock 3mm 2Hz fast-flash LEDs in red, orange, amber, yellow, green, blue, cool white, and warm white. All have a water-clear lens with a 15–30° viewing angle. Forward voltage by color: red/orange/yellow/amber ≈ 2.0–2.2V; blue/green/white ≈ 3.0–3.2V. Maximum forward current: 20mA. A series current-limiting resistor is required. Use our LED resistor calculator for the correct value. For AC or DCC power, add a bridge rectifier and smoothing capacitor — see the AC/DCC wiring guide. New to LEDs? Pre-wired LEDs include the resistor for plug-and-play operation.

2Hz vs. other rates in 3mm: The 2Hz rate is twice as fast as 3mm 1Hz slow flash and one-third the speed of 3mm 6Hz extra-fast. Choose 1Hz for prototypical railroad crossing signals and calm indicators. Choose 2Hz for safety markers, attention-getting warnings, and any application where a faster blink conveys urgency without the aggressive strobe effect of 6Hz. Choose 6Hz for emergency vehicle simulation and alarm strobes. For a subtle, ambient pulse, see 3mm 0.25Hz extra-slow. For organic flame effects, see 3mm flickering candle. For smooth brightness ramping, see 3mm fading/breathing.

Related categories: The same 2Hz animation is available in 5mm, 10mm, and 1.8mm sizes. For static (non-flashing) 3mm LEDs, see 3mm round-top LEDs. For animated LEDs with a pre-attached resistor wire, browse animated pre-wired LEDs. For wider-angle visibility from 3mm LEDs, see diffused 3mm LEDs.

2Hz means two complete on-off cycles per second. The LED blinks on and off twice within each second, producing a rapid double-blink that is noticeably faster and more attention-getting than the standard 1Hz (once per second) rate. Each on phase lasts approximately 250 milliseconds.
For prototypical accuracy, real crossing signals flash at approximately 1Hz. The 3mm 1Hz slow-flash LED is the correct match. The 2Hz rate is better suited for warning beacons, barricade flashers, and applications where a more urgent blink is desirable. Some modelers prefer 2Hz for visual impact at smaller scales, but serious prototype modelers choose 1Hz.
No. The flash rate has no effect on the resistor calculation. A 3mm 2Hz red LED uses the same resistor as a 3mm static red LED or a 3mm 1Hz red LED — the forward voltage and maximum current are identical. Use our LED resistor calculator for the correct value at your supply voltage.
With a ~50% duty cycle, average current draw is roughly 10mA. A CR2032 coin cell (220mAh) can power a single 3mm red 2Hz LED for approximately 20+ hours. A pair of AA batteries (2,500mAh) can run it for over 200 hours. Actual runtime varies with LED color, resistor value, and battery chemistry.
Yes, with a DC conversion circuit. Add a bridge rectifier and smoothing capacitor to convert AC/DCC to clean DC. See the AC/DCC wiring guide for full instructions.
Yes. Each animated LED runs on its own independent internal IC, so you can freely combine 2Hz, 1Hz, 6Hz, flickering, breathing, and static LEDs on the same power supply without any interference. Just make sure each LED has its own appropriate current-limiting resistor. Mixing animation types adds visual richness to dioramas and display builds.