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 wall power supplies are available in 5V and 12V, in current ratings from 1A up to 25A (320W). Supplies up to 5A output through a standard barrel connector; the higher-current 8.5A, 16.5A, and 25A units use screw-terminal outputs for hardwired installations. Choose 12V for pre-wired 12V LEDs, 12V built-in resistor LEDs, and LED strips. Choose 5V for Arduino, microcontroller boards, and 6V pre-wired LEDs — a 5V wall supply is close enough in voltage to run 6V pre-wired LEDs at slightly reduced brightness, which is often acceptable. For the full rated voltage on 6V or 9V pre-wired LEDs, use the matching AA 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 when a matching wall supply is not available.

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. Pre-wired 12V LEDs and 12V built-in resistor LEDs need a 12V supply. 12V flexible LED strips also require 12V. For Arduino and most microcontroller boards, use 5V. 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 1A per metre for 3528 strip and 1.4A 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 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 higher-current supplies — 8.5A (100W), 16.5A (200W), and 25A (320W) — use screw-terminal outputs 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.