an LED bulb needs to be supplied with a very low voltage variation

Although they are labelled as 12 Volt transformers, voltage variations of between 11.5 volts and 17 volts at peak are recorded on this type of transformer! That's right, up to 17 volts, a voltage difference of more than 5 volts.
In addition, some transformers designed for halogen bulbs deliver an alternating current output, which is transparent for a filament bulb but destructive for a bulb using LED technology.

LEDs should not be used with halogen transformers?

How do you choose the right transformer for your LED products?

To determine the right capacity for your transformer, you need to look at the power consumption of each item in the technical data sheet for our products.
If you only use one transformer, you need to add up the power consumption of each product.
However, some people prefer to use a small transformer for each bulb or LED product, to simplify wiring.
It is advisable to add an extra 15-20% power margin to your calculation, to avoid the transformer working at 100% of its potential.
This will increase its lifespan.

Starled transformers are essential and compulsory for all low-voltage LED bulb products... This section contains our different transformers in 12v DC (direct current supply) to use your LED bulbs but also all the low voltage products presented on the site... LED, LED Neon, LED Boards, Mr16 LED Bulb, Mr11 LED Bulbs, G4 LED Bulbs, LED Strip Lights, RGB Controllers, Special LED Dimmers, etc....