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555 IC - Transistor Tester
Is this a proper use of a PNP transistor?How can I convert a PNP to NPN transistor?PNP to NPN Transistor switchH-bridge PNP transistor overheatsWater level indicator with PNP transistor555 timing capacitor discharge via threshold inputHow does the NPN transistor in a 555 timer discharge the capacitor when the output is low?Transistor toggle by NPN and PNP - how is it build?Confusion with 555 transistor relay driver555 timer circuit switching automotive solenoid with PNP & NPN switching transistors
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$begingroup$
Why are Pins 7 and 5 floating for this 555 IC and how does an NPN and PNP transistor when connected to E B C act a switch?
Without the use of Pin 7 surely the capacitor cannot discharge which would render it useless?
transistors integrated-circuit 555 npn pnp
asked May 1 at 13:12
10wonga10wonga
162
$endgroup$
add a comment |
$begingroup$
Why are Pins 7 and 5 floating for this 555 IC and how does an NPN and PNP transistor when connected to E B C act a switch?
Without the use of Pin 7 surely the capacitor cannot discharge which would render it useless?
transistors integrated-circuit 555 npn pnp
asked May 1 at 13:12
10wonga10wonga
162
$endgroup$
2
$begingroup$
The output pin 3 is being used for discharging the capacitor when a transistor is connected. I'd recommend to simulate the circuit in LTspice or any other tool and check what happens. You can find the use of pin 5 on the internet.
$endgroup$
– Huisman
May 1 at 13:17
$begingroup$
10wonga, Are you still not understanding how the capacitor is discharged? Pin 7 is an open-collector output capable of sinking some current. Pin 3 is a push-pull output and able to sink still more current than pin 7. Pin 7 will be active only when pin 3 is LO. So they both can sink current at the same time (only pin 3 can source current), except that pin 3 can sink more than pin 7.
$endgroup$
– jonk
May 2 at 17:20
add a comment |
$begingroup$
Why are Pins 7 and 5 floating for this 555 IC and how does an NPN and PNP transistor when connected to E B C act a switch?
Without the use of Pin 7 surely the capacitor cannot discharge which would render it useless?
transistors integrated-circuit 555 npn pnp
asked May 1 at 13:12
10wonga10wonga
162
$endgroup$
Why are Pins 7 and 5 floating for this 555 IC and how does an NPN and PNP transistor when connected to E B C act a switch?
Without the use of Pin 7 surely the capacitor cannot discharge which would render it useless?
transistors integrated-circuit 555 npn pnp
transistors integrated-circuit 555 npn pnp
asked May 1 at 13:12
10wonga10wonga
162
asked May 1 at 13:12
10wonga10wonga
162
asked May 1 at 13:12
10wonga10wonga
162
asked May 1 at 13:12
10wonga10wonga
162
asked May 1 at 13:12
10wonga10wonga
162
162
2
$begingroup$
The output pin 3 is being used for discharging the capacitor when a transistor is connected. I'd recommend to simulate the circuit in LTspice or any other tool and check what happens. You can find the use of pin 5 on the internet.
$endgroup$
– Huisman
May 1 at 13:17
$begingroup$
10wonga, Are you still not understanding how the capacitor is discharged? Pin 7 is an open-collector output capable of sinking some current. Pin 3 is a push-pull output and able to sink still more current than pin 7. Pin 7 will be active only when pin 3 is LO. So they both can sink current at the same time (only pin 3 can source current), except that pin 3 can sink more than pin 7.
$endgroup$
– jonk
May 2 at 17:20
add a comment |
2
$begingroup$
The output pin 3 is being used for discharging the capacitor when a transistor is connected. I'd recommend to simulate the circuit in LTspice or any other tool and check what happens. You can find the use of pin 5 on the internet.
$endgroup$
– Huisman
May 1 at 13:17
$begingroup$
10wonga, Are you still not understanding how the capacitor is discharged? Pin 7 is an open-collector output capable of sinking some current. Pin 3 is a push-pull output and able to sink still more current than pin 7. Pin 7 will be active only when pin 3 is LO. So they both can sink current at the same time (only pin 3 can source current), except that pin 3 can sink more than pin 7.
$endgroup$
– jonk
May 2 at 17:20
2
2
$begingroup$
The output pin 3 is being used for discharging the capacitor when a transistor is connected. I'd recommend to simulate the circuit in LTspice or any other tool and check what happens. You can find the use of pin 5 on the internet.
$endgroup$
– Huisman
May 1 at 13:17
$begingroup$
The output pin 3 is being used for discharging the capacitor when a transistor is connected. I'd recommend to simulate the circuit in LTspice or any other tool and check what happens. You can find the use of pin 5 on the internet.
$endgroup$
– Huisman
May 1 at 13:17
$begingroup$
10wonga, Are you still not understanding how the capacitor is discharged? Pin 7 is an open-collector output capable of sinking some current. Pin 3 is a push-pull output and able to sink still more current than pin 7. Pin 7 will be active only when pin 3 is LO. So they both can sink current at the same time (only pin 3 can source current), except that pin 3 can sink more than pin 7.
$endgroup$
– jonk
May 2 at 17:20
$begingroup$
10wonga, Are you still not understanding how the capacitor is discharged? Pin 7 is an open-collector output capable of sinking some current. Pin 3 is a push-pull output and able to sink still more current than pin 7. Pin 7 will be active only when pin 3 is LO. So they both can sink current at the same time (only pin 3 can source current), except that pin 3 can sink more than pin 7.
$endgroup$
– jonk
May 2 at 17:20
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
Capacitor connected to pins six and two is charged and discharged by the output pin 3.
That is a common charge/discharge method for producing a 50% duty cycle.
Pin 5 can be left open like it is. Normally a capacitor is connected from pin 5 to ground. Pin 5 is the control voltage reference for pins 2 and 6. So a bypass capacitor might be needed for better stable reference voltage.
answered May 1 at 13:26
MarlaMarla
4,04811326
$endgroup$
add a comment |
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1 Answer
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$begingroup$
Capacitor connected to pins six and two is charged and discharged by the output pin 3.
That is a common charge/discharge method for producing a 50% duty cycle.
Pin 5 can be left open like it is. Normally a capacitor is connected from pin 5 to ground. Pin 5 is the control voltage reference for pins 2 and 6. So a bypass capacitor might be needed for better stable reference voltage.
answered May 1 at 13:26
MarlaMarla
4,04811326
$endgroup$
add a comment |
$begingroup$
Capacitor connected to pins six and two is charged and discharged by the output pin 3.
That is a common charge/discharge method for producing a 50% duty cycle.
Pin 5 can be left open like it is. Normally a capacitor is connected from pin 5 to ground. Pin 5 is the control voltage reference for pins 2 and 6. So a bypass capacitor might be needed for better stable reference voltage.
answered May 1 at 13:26
MarlaMarla
4,04811326
$endgroup$
add a comment |
$begingroup$
Capacitor connected to pins six and two is charged and discharged by the output pin 3.
That is a common charge/discharge method for producing a 50% duty cycle.
Pin 5 can be left open like it is. Normally a capacitor is connected from pin 5 to ground. Pin 5 is the control voltage reference for pins 2 and 6. So a bypass capacitor might be needed for better stable reference voltage.
answered May 1 at 13:26
MarlaMarla
4,04811326
$endgroup$
Capacitor connected to pins six and two is charged and discharged by the output pin 3.
That is a common charge/discharge method for producing a 50% duty cycle.
Pin 5 can be left open like it is. Normally a capacitor is connected from pin 5 to ground. Pin 5 is the control voltage reference for pins 2 and 6. So a bypass capacitor might be needed for better stable reference voltage.
answered May 1 at 13:26
MarlaMarla
4,04811326
edited May 1 at 14:03
answered May 1 at 13:26
MarlaMarla
4,04811326
answered May 1 at 13:26
MarlaMarla
4,04811326
answered May 1 at 13:26
MarlaMarla
4,04811326
4,04811326
add a comment |
add a comment |
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The output pin 3 is being used for discharging the capacitor when a transistor is connected. I'd recommend to simulate the circuit in LTspice or any other tool and check what happens. You can find the use of pin 5 on the internet.
$endgroup$
– Huisman
May 1 at 13:17
$begingroup$
10wonga, Are you still not understanding how the capacitor is discharged? Pin 7 is an open-collector output capable of sinking some current. Pin 3 is a push-pull output and able to sink still more current than pin 7. Pin 7 will be active only when pin 3 is LO. So they both can sink current at the same time (only pin 3 can source current), except that pin 3 can sink more than pin 7.
$endgroup$
– jonk
May 2 at 17:20