# This is a circuit schematic of a vending machine.The problem is i have a short circuit somewhere. ?

#### Saliba Majdalany

Joined Jan 17, 2021
9
So the thing is that this is a schematic of a vending machine. When we close the switch on a and c the LED1 should light up. But the thing is whenever I use my ampermeter to measure the current, it gives me 0 A everywhere. Even when I put the ampermeter besides the DC power source. Can anyone help me find the problem here in my circuit? Thanks
N.B: I asked my professor and she told me that there is a short circuit somewhere.
Any help is appreciated
Thank you very much

#### Attachments

• 35.3 KB Views: 38
Last edited by a moderator:

#### Papabravo

Joined Feb 24, 2006
21,306
This is not a schematic from an actual machine. This is a schematic from a simulation program. No idea how any of the components are connected to any power source since there are no explicit connections. What did you expect?

#### MrChips

Joined Oct 2, 2009
31,078
How do you measure current with an ammeter?
Where do you connect the leads of the ammeter?

LED1 and LED3 will never light up in a real circuit.

Is this a school assigment?

#### BobTPH

Joined Jun 5, 2013
9,264
A short circuit normally implies high current, not zero. What current are you measuring?

Bob

#### Saliba Majdalany

Joined Jan 17, 2021
9
How do you measure current with an ammeter?
Where do you connect the leads of the ammeter?

LED1 and LED3 will never light up in a real circuit.

Is this a school assigment?
Actually its a feature in multisim where u place the ammeter wherever u want and it will show you the result

#### Saliba Majdalany

Joined Jan 17, 2021
9
How do you measure current with an ammeter?
Where do you connect the leads of the ammeter?

LED1 and LED3 will never light up in a real circuit.

Is this a school assigment?
Im sorry but can you tell me what to d
This is not a schematic from an actual machine. This is a schematic from a simulation program. No idea how any of the components are connected to any power source since there are no explicit connections. What did you expect?
can you tell me how can i connect a power source ? I mean i already have a 5v dc power source but what should i do more??

#### Saliba Majdalany

Joined Jan 17, 2021
9
A short circuit normally implies high current, not zero. What current are you measuring?

Bob
Whatever current i try to measure it gives me 0 and the problem here is that im trying to light up led 1 when switch a and c are closed

#### MrChips

Joined Oct 2, 2009
31,078
Whatever current i try to measure it gives me 0 and the problem here is that im trying to light up led 1 when switch a and c are closed
The circuit is wrong. The LED will never light up.
Start with a single gate and see if you can make it light.