What voltage power supply should I use?

12V DC is the most common and versatile choice for diorama lighting. It allows multiple LEDs in series and is safe to handle. 5V USB power is convenient for portable displays. 9V batteries work for temporary or small setups.

Do I always need a resistor with LEDs?

Yes, almost always. LEDs need a current-limiting resistor to prevent burnout. The only exception is if you use a dedicated LED driver or a constant-current power supply. Never connect an LED directly to a battery or power supply without a resistor.

What current should I run my LEDs at?

Standard 3mm and 5mm LEDs typically run at 20mA for full brightness. For diorama use, 5-10mA often gives a more realistic, dimmer effect. SMD LEDs vary widely — check the datasheet. Running LEDs below their rated current extends their life.

How do I hide wiring in a diorama?

Route wires through channels carved in the base foam before adding terrain. Use thin enamelled copper wire (0.1-0.2mm) which is nearly invisible when painted. Fibre optics are excellent for tiny light points as the fibre itself is the light guide.

ModelCalcs

Lighting Calculator — LED Resistor & Power Planning

Plan LED quantities, calculate resistor values and size the power supply for diorama lighting effects.

Number of LEDs

Enter the total quantity

Supply Voltage

Value for supply voltage

LED TypeSelect the type

LED ColourSelect a colour or choose Custom to enter the LED forward voltage from its datasheet

LED Current

Typical: 20mA standard, 5-10mA for subtle effects

How We Calculate This

The calculator uses Ohm's law to determine the correct resistor value for your LED circuit.

Formula

R = (V_supply - V_forward) / I_led
Power (W) = (V_supply - V_forward) x I_led
Multiple LEDs in series share one resistor (up to the supply voltage limit)
Parallel strings each need their own resistor

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.