Soft Start Circuit

I love it, well done...👍

you love love-bombing, where have you learned that?

12Watt power loss i can see and there is no way around. Linear voltage drop/control does cost its price. Mosfet in TO220 will survive, but if kids are testing im not sure if the mosfet without heatsink has a long life. All this without taken nonlinear behaviour of the bulb. Why do you think the power losses are low? Relative low to what?

In GreatScott’s video the relay coil draws 36mA from the 12V source with negligible loss in the contacts themselves resulting in a power loss of 0.43W keeping the relay closed. This circuit though has negligible losses on the gate side for keeping the transistor running but now has a noticeable loss on the output since the mosfet’s channel isn’t as good a conductor as a relay’s contacts. A 0.26V drop passing 4.08A in its on state means the transistor is consuming 1.06W of power, which is still doable with properly sized heat sinking and beefy components but still means there’s more losses in this circuit compared to a relay. A relay also has the added benefit of typically higher ratings than could be achieved by most transistors since the metal contacts are easier to make larger and stronger whereas the specified transistor here may either need to be swapped out if not properly rated or be chosen to handle voltages and currents that may be serious overkill most of the time. It’s not that relays are just inferior old tech that should be replaced by transistors, they’re just a different piece of tech with different pros and cons. The transistor solution would certainly be a lot quieter though so long as nothing catches fire.

1-2W on a shitty mosfet with 50W load is already good, for a very small circuit with few components... you can use relays, but i prefer solid state stuff, moving parts sucks.