Hi,
3.3V x 1.0A = 3.3W .. this is the power you need to dissipate as heat. --> You will need a heatsink.
I would like to use a mosfet as a dummy load to vary the output of the regulator
A bit pedantic: You don´t want to "vary the output". Either you want to adjust the current or the load resistance or the load impedance.
Would this be possible with the mosfet alone
A MOSFET alone will not work... because then there is nothing for adjusting...
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There are several solutions:
* constant current sink circuit
Often used for precise measurements. One can select 0.5A for example and it will draw exactly 0.5A independet of applied voltage(as laong as possible) and independent of temperature.
Do a search for "constant current sink" or "low side constant current source"
* variable resistor circuit
Rarely used. You may set a resistance of 6Ohms and it will stay 6 Ohms independent of applied voltage (as long as possible) and independent of temperature.
(In opposite to the constant current sink here the current depends on voltage and follows I = U / R)
Do a search for "variable resistor circuit".
* or something simple inbetween
A simple raw load adjustment. You may optimize it in direction of "constant current" with the use of a zener, or you may use it more like a constant resistor. But both are not exact. They will drift with temperature and drift with applied voltage.
Often used because it´s cheap. For this you will additionally need a current meter to monitor the current .... and maybe re adjust for the current you want)
You need a MOSFET, maybe a zener, a pot, a power resistor and a couple of standard resistors)
Klaus