stepping down from 12 volts

[michael strohm]

Need advice stepping down power supply from 12 volts dc at 3 amps to 6 volts dc at 3 amps using resistors

 

[crutschow]

Need advice stepping down power supply from 12 volts dc at 3 amps to 6 volts dc at 3 amps using resistors

A resistor will give the same efficiency as a linear regulator but without the regulation.
3V @ 6A will have a power dissipation (waste heat) of 18W to drop from 12V, which requires a hefty heat-sink and possibly a fan.

Much better to use a switching buck regulator which typically has an efficiency around 90% so would dissipate less than 2W.

 

[ronsimpson]

Using resistors to drop voltage only works if the load never changes, 3A. As soon as the load changes the voltage will change.

 

[Nigel Goodwin]

Yes, you need to give far more details of exactly what you're doing - but unless the load is constant, and you want an in-built toaster, then resistors aren't the way to go.

 

[danadak]

Pretty simple low cost and has over T protection, and plenty of margin :

https://www.aliexpress.us/item/2255799926298895.html?spm=a2g0o.productlist.main.71.43dc4b5cJf8Qtx&algo_pvid=5cc9c5e2-ea60-472d-aabe-ff4a14b5bcd1&algo_exp_id=5cc9c5e2-ea60-472d-aabe-ff4a14b5bcd1-35&pdp_npi=3%40dis%21USD%212.13%211.81%21%21%21%21%21%40211bc71916822407946235695d0792%2110000000290785912%21sea%21US%21784751897&curPageLogUid=a9kr2NJewnCa

Regards, Dana.

 

[Nigel Goodwin]

Pretty simple low cost and has over T protection, and plenty of margin :

https://www.aliexpress.us/item/2255799926298895.html?spm=a2g0o.productlist.main.71.43dc4b5cJf8Qtx&algo_pvid=5cc9c5e2-ea60-472d-aabe-ff4a14b5bcd1&algo_exp_id=5cc9c5e2-ea60-472d-aabe-ff4a14b5bcd1-35&pdp_npi=3%40dis%21USD%212.13%211.81%21%21%21%21%21%40211bc71916822407946235695d0792%2110000000290785912%21sea%21US%21784751897&curPageLogUid=a9kr2NJewnCa

Regards, Dana.

Nice one, and incredibly cheap.