Explain me this OR gate circuit

[blghs]

Hi
1. Can you explain,the circuit,of OR gate, at the url:
https://www.technologystudent.com/elec1/dig2.htm
the picture with 2 BJT NPN transistors,
in the state of:input a=0,input B=0,
why the output is 0 ?
according to the circuit,the bulb should light,
because,there is a complete path from the 6+ volt ,
to the 0 volt.

2. Does that circuit, contains only one,voltage source,
or 2?

 

[stefano.delfiore]

Re: OR GATE

Hi
1. Can you explain,the circuit,of OR gate, at the url:
https://www.technologystudent.com/elec1/dig2.htm
the picture with 2 BJT NPN transistors,
in the state of:input a=0,input B=0,
why the output is 0 ?
according to the circuit,the bulb should light,
because,there is a complete path from the 6+ volt ,
to the 0 volt.

2. Does that circuit, contains only one,voltage source,
or 2?

I agree with you! I think that there a lot of errors in the pictures of circuits. For example if you see the nand circuit, the lamp is connected across a short circuit!

The or circuit could be right for example, without the lamp and as output the voltage across the 680 Ohm resistor.

stefano

 

[A.Anand Srinivasan]

Re: OR GATE

i think the negative terminal of the bulb should be connected to the collector with the direct line from the supply to the collector disconnected for both the AND as well as OR gate circuits.....

 

[rx5]

OR GATE

schematic error on AND transistor circuit...