i use arduino. in the project I need an additional power supply of 1.5v. i use ams1117. my question is could i connect the arduino pin to the gnd pin of the ams1117-1.5. and thus control the power supply whether it is on or off. or do I have to switch off the voltage to the device with a transistor?
The current limit of arduino pins is 20ma, regardless of fact either it used as high voltage source or as GND. So if your 1.5v circuit consume much power, using the mosfet is mandatory.
BTW, please show your circuit diagram. Why do you want to control load by regulator GND pin? Wouldn't it be better to manage power directly on the load?
First of all, your schematic is incomplete, because you didn't show all wiring. Where is a GND of the module connected?
For answering this question we need to know a specifications of module.
And one more thing - I don't have much experience with ams1117, but I think that turning off the load by disconnecting the ground on the regulator is a bad idea, this circuit will not work
yes, the schematic is incomplete. because only the idea of direct control of the ams1117 is important.
if you looking for help - you must provide as much information as possible.
For the part you provided, it's impossible to answer the question.
I don't see why the module is important. whether the consumer is ice or a motor or some electronics. the question is whether the ams1117 can be controlled via gnd? if no answer can be given to that, as far as I'm concerned, the topic can be closed.
NO it can't, if you remove gnd connection you have the risk of a higher output voltage appearing at the regulated output pin because of the higher input voltage.
If you want to be able to enable and disable a regulator, look up DC-DC converters, some have enable pins.
Tom... 
tested.
Vin=8v
Gnd= not connected or 8V
Out=7v
Thanks. until you answered, I physically tried it.
Yes, an experimenter... well done..
I'd have tried it here, but no spare 1117.
Tom...