# boosting regulator supply

hello all,

i tried searching my my particular answer and only come up with schematics and such without actual operation explanation.
or i did not fully understand (very possible).
would appreciate a point in the right direction or quick answer, please

with the following attached design:
does the input have to be equivalent to output for current?
if i have wall wart - 12vdc @ 1A and need 5v @ +/- 5A for output, will this design pull the 5A from wart or create from the TIP2955/MJE2955 without burning the wall wart?
if i understand correctly, i can add multiple 2955’s for more current but not a need right now.
I know i will need a large heat sink and/or fan. i just need a one time shot for more amperage with my project without having to spend more money since i have all these parts on hand.

Current (Amps) is a measure of how many electrons per unit time are passing through a conductor. Since a circuit can’t create electrons the current going into the circuit has to be the same as the current you want to get out of the circuit. The transistor just shares the load to keep from frying the 1A regulator.

with the following attached design: does the input have to be equivalent to output for current?

Yes.

if i have wall wart - 12vdc @ 1A and need 5v @ +/- 5A for output, will this design pull the 5A from wart or create from the TIP2955/MJE2955 without burning the wall wart?

The circuit you showed is not a boosting regulator it is a simple step down linear regulator. The TIP2955 is just a simple transistor not a regulator.

What you need is a boost or step up switching regulator. Something like a TPS40210 or a TPS61256. With that you can swap excess current for voltage. The other way round is called a buck switching regulator where you swap excess voltage for current.

However you can not get more power than you put in. So 12V at 1A is 12W of power. If you could convert at 100% you could get 5V at 2.4A. But more likely your efficiency is going to be 80% so you get (12 * 0.8) / 5 = 1.92A.

if i understand correctly, i can add multiple 2955's for more current

No you can't. 1) It is not a regulator 2) You can not create power only distribute the voltage and current in another way and loose some power into the bargain.

Have a read of this. https://www.dimensionengineering.com/info/switching-regulators

i did not see that article. very helpful indeed. THANX!

off to do more googling.

have a good one