hi i bough a cheapo breadboard power supply off the bay which supplies 3.3 vand 5 v.
now when i ramp up the volts the 3.3v is mostly constant off the 3.3 v reg.(can be 9v supplied)
but when i ramp up the v on the 5 v reg its never 5v but can be 7v or more ,so is my 5v reg faulty ?
should it only give 5v no matter how much i feed it ?in which case i need to replace it .
within reason of course of the regs data sheet parameters ..
The 5V should be 5V, just as the 3.3V is 3.3V.
Perhaps you can measure the pins of the voltage regulator with a multimeter.
Are you sure you are testing the right pins? Some pins are the input voltage.
You should report it as broken.
"is my 5v reg faulty"
Possibly.
Are you running it with no load? Try adding 1K resistor for 5mA load, see if it does the same.
Do you have any input & output capactitors on it? You may need those as well. Check the datasheet on the part.
http://www.advanced-monolithic.com/pdf/ds1117.pdf
no load , i may as well replace the reg as theyre very cheap but my wallwart has adjustable v out so can control it ,thanx
I seem to have the same problem, at the AMS1117 5.0, I measure 7.65V. I used the breadboard supply only a few times, and it was 5.0 V before. I maybe have shortened the + and - pins of the output for a short time with a multimeter test probe. Is thisenough to destroy the regulator?
I had an Arduino nano on the breadboard connected via USB and via the 5V pin and an analog pin to the 7.65V rail of the breadboard. Maybe enough voltage to harm the Arduino too?
Regulators are almost fool-proof.
It could be oscillating.
Try an electrolytic cap (10-100uF) from 5volt to ground, before you throw it out.
Leo..
This may be a stupid question but are you aware that the pin-out of 1117 is different from that of 7805? The tab or center pin of 1117 is output, while the tab or center pin of 7805 is ground. If you know the correct pin out and still measure 7V, the regulator is dead. If you supplied 7V to your arduino analog input, it's damaged (unknown degree of damage).