12v 3mm Round Top Clear Lens LED - Blue LED - Ultra Bright (5v-15v)

The 3mm Blue 12V LED with Built-In Resistor (Round Top) connects directly to any 5V–15V DC power source — no external resistor required. The internal current-limiting resistor is built into the LED body itself. Connect the anode (long lead) to positive, cathode (short lead) to ground, and it lights up at the correct brightness. Standard 3mm (T-1) round top package with clear lens for a focused beam.

The 3mm (T-1) head is the smallest standard DIP size — scales realistically at HO (1:87) and N (1:160) scale. Small enough to hide inside model structures, dollhouses, and tight enclosures.

Who uses these?

• Automotive dashboard and gauge cluster: CB/ham radio S-meter backlight (Cobra 29, Uniden Bearcat), modern cluster accent. Drop-in replacement for burnt-out indicator bulbs in GM Silverado/Sierra, Toyota Tacoma, Ford F-150, Honda Accord, Jeep Wrangler, and other pre-2010 vehicles. Plug directly into 12V instrument cluster circuits.
• Model railroad layouts: cool-toned accent for commercial and industrial structures. Wire directly to your 12V accessory bus — no resistor math, just solder and go. Works on DCC and DC layouts alike. 3mm works at HO (1:87) and N (1:160) scale.
• CB and ham radio: S-meter and channel display backlight replacement for Cobra 29, Uniden Bearcat, Kenwood, Icom, and Yaesu transceivers running on 12V DC.
• PC case modding: Tap the yellow wire (12V) on any spare Molex connector for HDD bay accents, cable shroud glow, and PSU shroud edge lighting. No resistor, no regulator.
• RV, camper, and marine panels: Runs directly off your 12V house battery or boat bus. Panel indicators for bilge pump, battery switch, and blower status. Not waterproof — mount in a protected location.
• Arcade cabinets and pinball: Fits inside translucent Sanwa/Seimitsu pushbuttons powered from a JAMMA harness. Also works for backbox and playfield illumination in pinball restorations.
• RC crawlers: Scale headlights and taillights for Traxxas TRX-4, Axial SCX10, and 1/10 scale truck bodies. Direct-compatible with 7.2V–14.8V LiPo packs under load.
• Motorcycle gauges: Backlight your speedo and tach on vintage Honda CB, Yamaha, and Kawasaki cafe racer builds.

Why built-in resistor?

No resistor calculator needed. Standard LEDs require you to calculate and solder an external resistor for every voltage — get it wrong and the LED burns out instantly. These LEDs have a current limiter built into the lens itself. Connect to anything from 5V to 15V and they regulate themselves to 20mA.

We don’t recommend running them continuously at 15V, but they handle occasional voltage spikes — this is particularly useful in automotive applications where charging systems routinely push 14–15V. With all that said, if your project allows it, using a standard LED with an external resistor is still the best practice. It keeps the heat further away from the diode itself, which extends lifespan. But when space is tight or simplicity matters, these 12V built-in resistor LEDs are the solution.

Important notes

• Polarity matters: Long lead = positive (+), short lead = negative (−). Reversing polarity will not damage the LED, but it will not light.
• DC only: Do not connect directly to AC. For model railroad AC transformers or DCC track power, convert to DC first with a bridge rectifier.
• Fits all standard 3mm LED holders, bezels, and panel-mount clips.

Need wider light spread? See our 12V 3mm Cube LEDs — frosted body scatters light for even area illumination.

Need pre-wired instead?

If you need wire leads already attached, see our 12V Pre-Wired LEDs — same built-in resistor concept but with 6" pre-soldered leads and heat-shrink protected connections. No soldering required at all.

Pair with

• Hook-up wire — 22–24 AWG for clean wiring runs
• Switches — toggle, rocker, and mini slide for control panels
• 12V Power Supplies — wall adapters and bench supplies
• 3mm LED Holders / Bezels — snap-in panel-mount bezels
• Heat shrink tubing — protect solder joints

Sold individually (1 LED per quantity ordered).