Ohlm's Law Simplified for Miniaturists

While making sure I understood the relationship between watts, volts, amps, and miliamps in miniature lighting, particularly LED's by Novalyte, I learned this simple formula.

P = E x I

which translates into: P(power in watts) = E (Electromotive Force or Volts) x I (current or amps)

Conversely, for further information:
1,000 miliamps = 1 amp

Most of us don't really want to know about formulas, we just want to do miniatures and light them up for all to see. But understanding these formulas helps us make informed decisions regarding our lights and transformers. Another interesting formula that helps us understand the relationship between transformers and the number of lamps they can support is:

Watts divided by Voltage equals Current (or amps).

While you may not care about these formulas, I wanted to lay them out in this blog so that I (or anyone interested) could have ready access to them.

With a little algebra, you can estimate your electrical needs.

Novalyte LED's and Transformers

The average 12 volt miniature light bulb is 60 mA (milliamps). LEDs take less, with 1 LED being 35 mA and 4 LEDs being 70 mA (or almost the equivalent to one miniature bulb). The more LEDs on a line, the less power each individual LED takes. I’ve provided the charts below for reference.

Novalyte Lamps:

1 light strip, can light, or tab = 35mA
2 light strip = 35mA
3 light strip = 45mA
4 light strip = 70mA

Cir-Kit Transformers (mA as reported by Cir-Kit Concepts):

CK1009A = 10 watts (1,000mA)
CK1009B = 5 watts (500mA)
CK1009D = 40 watts (4,000mA)
CK1009C = 20 watts (2,000mA)
CK1009F = 3 watts (300mA)

To determine transformer requirement:
Combine total number of mA in each lamp that will be on one transformer

Example if you were to use 5 of the 4 light Novalyte LED lamps (5 lamps x 70mA = 350mA) you would require the 5W transformer (500mA) or Cir-Kit model CK1009B.