I am doing a project where the components require 3.3v input instead of 5v, but my arduino pro mini can only supply 5v. Thus, I bought a lm1117t-3.3 voltage regulator to regulate the voltage, but the output from the voltage regulator is not 3.3v, but around 1v. This is the way I connected the voltage regulator, please give me some suggestions to overcome this problem, thank you.
This is how a typical LM1117 3 Pin Fixed Regulator is shown in circuit schematics:
This is symbolic/logical, NOT! Physically.
This is how they are typically physically wired, text side forward:
If you physically wired it as you show, Vin-Gnd-Vout, that will not work, and may have damaged it.
Of course, not all regulators use this pin out. The LM780x series does use Vin-Gnd-Vout. Always check the data sheet for your part's manufacturer.
Additionally, the LM1117 series requires a 10 µF Tantalum output capacitor. It may also need an input capacitor depending on how far the power supply is. It also has a minimum output load to be stable. 5 mA or so should be enough. A Led + Resistor would work.