Oh, I forgot one point IF you have a scope it is unlikely to show much noise UNLESS the bandwidth is at least 100Mhz.
However you could look critically at both input and output of the 117, for larger things... What is the dropout of the 117? If the input is less the output plus that dropout you will NOT get good regulation... checking lt117 datasheet now.
AH, you MUST have at least 1.5V difference between in and out, that at 0.02A, but for real world I would want the 2.5v difference. SO.. unless you are using it at no more than 3VDC out you MIGHT have issues. Personally I'd prefer a low dropout regulator over this one... even thought it IS lower than the 3vdc difference needed by the lm317
Well I happen to have one, but not really sure how do I get to see the noise... Its a 20MHz HAMEG which is laying around since my early school days... I connected the Power supply but do not get to see the noise, when on AC it shows 0V flat-line, when on DC it shows 5V flat-line. What settings do I need to put on the dials?
The datasheet for the LD1117v33 says that the dropout voltage is max 1.1V for 800mA, typical 1.05 for 500mA. It is supposed to be a low voltage dropout regulator. :confused:
The first thing I notice is that you are not using ceramic decoupling capacitors. They must be 0.1uF ceramic or they will not filter out high frequencies.
You failed to mention it was a stand alone Arduino.
The description "not working" is not very helpful. Measure the voltage on the regulator's input and output pins to see if power is getting through.
Basically solder less bread boards are crap, I never use them, nor do I recommend their use.
Well, I never mentioned Arduino either :)
Sorry, indeed Not working means nothing. What I meant to say is that it is working but I get the same noise on the screen (as in the picture). Occasionally there appears something readable, like a digit or a letter from whatever there was supposed to be printed, which means that reading the I2C sensors works.
Already measured voltage seems OK. Depending on the supply I use I get 3.350V - 3.365V output from the LDO.
Both mentioned ceramic caps. I did not know it could make a difference (I'm using some MKP ones I had from my audio experiments) I will try this to see...
I'm also going to try and have it tested with the normal Arduino @5V and see...
Oh, one thing I forgot to mention is that in order to eliminate any issues with my regulation, I bypassed it by using the Arduino UNO onboard regulator. So I connected the Arduino UNO to the USB port of the laptop and got the 3.3V output pin to power my breadboard (removing all regulation-related components).
I do get the exact same behavior. When the UNO gets its power off of the USB charger the OLED displays garbage. When it gets it from the Thinkpad, everything is well. So any PSU noise does even get through the 3.3V regulator of the UNO.
Again, thank you all for your time and suggestions.