Power Supply / Drivers

LED power supplies, battery holders, and constant-current drivers for powering LED projects from any source.

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LED power supplies, battery holders, and constant-current drivers for powering LED projects from any source. Whether you need a regulated AC-to-DC wall supply for a permanent installation, a battery pack for a portable or model railroad layout build, or a drop-in current-limiting driver that eliminates resistor calculations entirely, this section covers all three.

AC-to-DC power supplies are available in 5V and 12V, in current ratings from 1A up to 25A (320W). Our wall supplies up to 5A output through a standard barrel connector; the high-output supplies (3A, 5A, 8.5A, 16.5A, and 25A) use screw terminals for the AC input and the DC output, for hardwired installations. Choose 12V for pre-wired 12V LEDs, 12V built-in resistor LEDs, and LED strips. Choose 5V for the LEDs and other 5V parts of Arduino and microcontroller projects (an Arduino board’s barrel jack expects 7–12V, so power the board itself from a 12V adapter), and for 6V pre-wired LEDs — the 6V LEDs work great on a 5V wall supply, at slightly reduced brightness. For the full rated voltage on 6V or 9V pre-wired LEDs, use the 4xAA (6V) or 9V battery holder instead.

Battery power supplies use AA cells (1, 2, 3, 4, or 8 cells for 1.5V, 3V, 4.5V, 6V, or 12V), a standard 9V block battery, or a 3V CR2032/CR2025 coin cell. These are the go-to option for portable builds, dioramas, model railroad modules that run untethered, and any project where running a power cable is not practical. The 6V and 9V battery holders provide the exact voltage for 6V and 9V pre-wired LEDs (we do not carry 6V or 9V wall supplies).

The 20mA constant-current LED driver is a small inline component that replaces the current-limiting resistor — connect it in series with any standard LED and it maintains exactly 20 mA regardless of minor supply voltage fluctuations. No voltage calculation, no resistor selection. Useful for mixed-voltage builds, vehicle electrical systems where voltage varies, and situations where you simply want to skip the math.

Frequently Asked Questions

Match the supply voltage to your LED type. 12V flexible LED strips require 12V. Pre-wired 12V LEDs work on 5V too, a little dimmer (a 12V supply gives full brightness), and 12V built-in resistor LEDs run on 5–15V (round tops) or 7–15V (cubes). For the LEDs and other 5V parts of Arduino and most microcontroller projects, use 5V; an Arduino board’s barrel jack expects 7–12V, so power the board itself from a 12V adapter. 6V pre-wired LEDs can run on a 5V wall supply at slightly reduced brightness, or at full brightness using the 4 AA (6V) battery holder. 9V pre-wired LEDs are best powered by the 9V battery holder — we do not carry a 9V wall supply. When in doubt, 12V is the most versatile choice and powers the widest range of pre-wired LEDs, strips, and accessories.
Add up the current draw of every LED and component on the supply. A standard 5mm LED draws about 20 mA (0.02A). A 12V LED strip draws roughly 0.4A per metre for 3528 strip and 1.2A per metre for 5050 strip. Pre-wired LEDs each draw about 15–20 mA. Total the draw of all connected LEDs, then choose a supply rated at least 20 % above that figure. Example: 20 pre-wired LEDs × 20 mA = 400 mA total → a 1A supply gives comfortable headroom. For large LED strip installs, step up to the 5A, 8.5A, 16.5A, or 25A units.
All of our wall supplies up to 5A output through a standard 5.5 mm × 2.1 mm barrel connector, which plugs directly into the barrel jack on LED strips, controllers, and accessories. The high-output supplies — 3A (35W), 5A (60W), 8.5A (100W), 16.5A (200W), and 25A (320W) — use screw terminals for the AC input (you wire the power cord to them) and for the DC output, intended for hardwired installations in enclosures, under-cabinet lighting runs, and commercial LED strip installs. The DC barrel connector and power supply splitter accessories are compatible with the barrel-connector supplies only.
Yes — battery holders are a direct substitute for a wall supply as long as the battery voltage matches the LED's rated voltage. The 8 AA battery holder outputs 12V, making it compatible with all 12V pre-wired LEDs and 12V built-in resistor LEDs. The 4 AA holder (6V) is the preferred power source for 6V pre-wired LEDs; the 9V battery holder for 9V pre-wired LEDs. Battery capacity is the key variable: a standard AA alkaline cell holds about 2500 mAh. Divide total LED current draw into that to estimate runtime. For example, 10 pre-wired LEDs at 20 mA each = 200 mA draw → roughly 12 hours from a fresh set of AAs.
The 20mA LED driver is a small two-terminal through-hole component that replaces the current-limiting resistor in series with an LED. It regulates current to exactly 20 mA regardless of minor supply voltage fluctuations — no calculation required, just drop it into the circuit in place of a resistor. It is particularly useful when: your supply voltage is uncertain or varies (e.g. vehicle electrical systems that swing between 11V and 14.4V); you are connecting LEDs across different voltage rails and want consistent brightness; or you simply want to skip the resistor math on a prototype. For large LED arrays where cost matters, individual resistors are more economical; for one-off builds and breadboard prototyping, the driver is the fastest path to a correctly-driven LED.
The female DC barrel connector (5.5 mm OD × 2.1 mm ID) lets you terminate a custom wire run so it plugs directly into any of our barrel-connector power supplies — useful for extending a supply lead, building a custom LED harness, or adding a barrel jack to a project enclosure. The power supply splitter converts one barrel output into two parallel connections so you can run two independent LED circuits from a single supply — for example, powering a pre-wired LED installation and an LED strip controller from the same 12V 5A supply.