Hey all I am having an issue using this AMS1117-3.3 SMD:

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According to its documents it says its either a fixed or adjustable version? So I hook it up as I see in the documents:

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The left pin (1) being Ground.

The middle pin (2) being the 3.3vdc output.

The right pin (3) being the 5vdc input.

Once I hook all those up, I test it with my voltmeter on 20 and i get a reading of 0.09vdc????????

I've already tried 3 of these to make sure I didnt blow it or anything but it keeps saying that readout.

Am I missing something here? This must be the adjustable version since I can not just hook it up and expect 3.3vdc to come out?

I also tried to just step down from 5vdc to 3.3vdc using 100ohm resistor but that only produced around 4vdc output....

Here is the way I hooked it up:

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The document I am reading is here

And also on my breadboard:

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And what I have it connected to (ESP8266 ESP-12f) this is its document stating above 80mA average:

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Alright this is what I have to work with:

2 x .1uF 100v Stack Metal Film

2 x 1N4148TA 100v 0.2A

2 x 35v 470uF

2 x 25v 47uF 20%

2 x 35v 220uF

2 x 10v 100uF 20%

2 x 1.0uF 50v 20%

Any of these work to step it down or use for the capacitors on the AMS1117?

Alright does this look like a good one to go by?

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  • 3
    \$\begingroup\$ Did you include input and output capacitors? Does the regulator draw current or get warm? Are you sure they aren't fakes? \$\endgroup\$ – pericynthion Apr 2 '17 at 6:51
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    \$\begingroup\$ You need a minimum load too, on top of @pericynthion capacitors. \$\endgroup\$ – winny Apr 2 '17 at 7:20
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    \$\begingroup\$ The output capacitor probably has a minimum ESR requirement as well: electronics.stackexchange.com/questions/200565/… \$\endgroup\$ – Peter Smith Apr 2 '17 at 13:40
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    \$\begingroup\$ Two things. One, your soldering is horrible. Two, the chip pins are too small to fit in the breadboard properly like that. Bonus, are you sure you got real chips? They may be fake or broken. Especially if all 3 are like that. \$\endgroup\$ – Passerby Apr 3 '17 at 3:01
  • \$\begingroup\$ Solder some wires onto a new regulator and put it in the breadboard with just input power and no load. If you don't get 3.3V it's a fake. \$\endgroup\$ – Bruce Abbott Apr 3 '17 at 3:29

You have the 3.3V version not the adjustable version as shown by the part number.

See the datasheet under electrical characteristics: the regulator wants a minimum load of 10mA. If you directly measure the unloaded output, your multimeter's impedance is too high for the chip to regulate.

Page four of your linked datasheet also states that the output capacitor is not optional.

  • \$\begingroup\$ Can I not use some resistor's to drop the 5vdc down to 3.3vdc? \$\endgroup\$ – StealthRT Apr 2 '17 at 22:05
  • \$\begingroup\$ For a voltage reference, yes. For a power supply, no. I highly recommend you read and understand this: electronics.stackexchange.com/questions/55622/… \$\endgroup\$ – replete Apr 2 '17 at 23:25
  • \$\begingroup\$ @stealth no a voltage divider is not a good idea, and a series resistor is just as bad. \$\endgroup\$ – Passerby Apr 3 '17 at 3:04

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