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.
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1\$\begingroup\$ Did you use the recommended capacitors, and put a minimum load on the output? A led and a 200 ohm resistor should be enough. \$\endgroup\$– PasserbyJan 29, 2016 at 3:59
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1\$\begingroup\$ Oh... if that's how you wired it, physically, that's wrong. Looking at it from the front where the text is, left to right, it's supposed to be Ground, Out, In. It's not physically In, ground, out. \$\endgroup\$– PasserbyJan 29, 2016 at 4:04
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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.