What kind of transistor turns on with 0.2 volts?
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$begingroup$
I need a circuit to turn on a LED with 0.2 volts.
I want to do it with a transistor as a switch.
What kind of transistor will turn on at this voltage?
transistors mosfet bjt jfet
asked 13 hours ago
seyyedali hosseiniseyyedali hosseini
122
New contributor
seyyedali hosseini is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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show 2 more comments
$begingroup$
I need a circuit to turn on a LED with 0.2 volts.
I want to do it with a transistor as a switch.
What kind of transistor will turn on at this voltage?
transistors mosfet bjt jfet
asked 13 hours ago
seyyedali hosseiniseyyedali hosseini
122
New contributor
seyyedali hosseini is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
5
$begingroup$
Pretty much none of them. I would recommend amplifying the signal before trying to use it as a switch, perhaps with a comparator.
$endgroup$
– Hearth
13 hours ago
5
$begingroup$
Instead of asking about a transistor which needs to turn on with only 0.2 V (there aren't any but please prove me wrong!) and assume that you can do this with only one transistor (you can't but I'd like to be proven wrong again), describe what your requirements are and ask what solutions exist. A LED will not light up with 0.2 V so there must be some other voltage present. Why 0.2 V? Do research on similar setups (switching LEDs) and learn how that's done.
$endgroup$
– Bimpelrekkie
13 hours ago
2
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
12 hours ago
$begingroup$
0.2V isn't enough to run an LED; if you have a rail that'll drive an LED then you can use a comparator.
$endgroup$
– TimWescott
9 hours ago
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
9 hours ago
|
show 2 more comments
$begingroup$
I need a circuit to turn on a LED with 0.2 volts.
I want to do it with a transistor as a switch.
What kind of transistor will turn on at this voltage?
transistors mosfet bjt jfet
asked 13 hours ago
seyyedali hosseiniseyyedali hosseini
122
New contributor
seyyedali hosseini is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
I need a circuit to turn on a LED with 0.2 volts.
I want to do it with a transistor as a switch.
What kind of transistor will turn on at this voltage?
transistors mosfet bjt jfet
transistors mosfet bjt jfet
asked 13 hours ago
seyyedali hosseiniseyyedali hosseini
122
New contributor
seyyedali hosseini is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 13 hours ago
seyyedali hosseiniseyyedali hosseini
122
New contributor
seyyedali hosseini is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 13 hours ago
seyyedali hosseiniseyyedali hosseini
122
New contributor
seyyedali hosseini is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 13 hours ago
seyyedali hosseiniseyyedali hosseini
122
asked 13 hours ago
seyyedali hosseiniseyyedali hosseini
122
122
New contributor
seyyedali hosseini is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
seyyedali hosseini is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
seyyedali hosseini is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
5
$begingroup$
Pretty much none of them. I would recommend amplifying the signal before trying to use it as a switch, perhaps with a comparator.
$endgroup$
– Hearth
13 hours ago
5
$begingroup$
Instead of asking about a transistor which needs to turn on with only 0.2 V (there aren't any but please prove me wrong!) and assume that you can do this with only one transistor (you can't but I'd like to be proven wrong again), describe what your requirements are and ask what solutions exist. A LED will not light up with 0.2 V so there must be some other voltage present. Why 0.2 V? Do research on similar setups (switching LEDs) and learn how that's done.
$endgroup$
– Bimpelrekkie
13 hours ago
2
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
12 hours ago
$begingroup$
0.2V isn't enough to run an LED; if you have a rail that'll drive an LED then you can use a comparator.
$endgroup$
– TimWescott
9 hours ago
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
9 hours ago
|
show 2 more comments
5
$begingroup$
Pretty much none of them. I would recommend amplifying the signal before trying to use it as a switch, perhaps with a comparator.
$endgroup$
– Hearth
13 hours ago
5
$begingroup$
Instead of asking about a transistor which needs to turn on with only 0.2 V (there aren't any but please prove me wrong!) and assume that you can do this with only one transistor (you can't but I'd like to be proven wrong again), describe what your requirements are and ask what solutions exist. A LED will not light up with 0.2 V so there must be some other voltage present. Why 0.2 V? Do research on similar setups (switching LEDs) and learn how that's done.
$endgroup$
– Bimpelrekkie
13 hours ago
2
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
12 hours ago
$begingroup$
0.2V isn't enough to run an LED; if you have a rail that'll drive an LED then you can use a comparator.
$endgroup$
– TimWescott
9 hours ago
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
9 hours ago
5
5
$begingroup$
Pretty much none of them. I would recommend amplifying the signal before trying to use it as a switch, perhaps with a comparator.
$endgroup$
– Hearth
13 hours ago
$begingroup$
Pretty much none of them. I would recommend amplifying the signal before trying to use it as a switch, perhaps with a comparator.
$endgroup$
– Hearth
13 hours ago
5
5
$begingroup$
Instead of asking about a transistor which needs to turn on with only 0.2 V (there aren't any but please prove me wrong!) and assume that you can do this with only one transistor (you can't but I'd like to be proven wrong again), describe what your requirements are and ask what solutions exist. A LED will not light up with 0.2 V so there must be some other voltage present. Why 0.2 V? Do research on similar setups (switching LEDs) and learn how that's done.
$endgroup$
– Bimpelrekkie
13 hours ago
$begingroup$
Instead of asking about a transistor which needs to turn on with only 0.2 V (there aren't any but please prove me wrong!) and assume that you can do this with only one transistor (you can't but I'd like to be proven wrong again), describe what your requirements are and ask what solutions exist. A LED will not light up with 0.2 V so there must be some other voltage present. Why 0.2 V? Do research on similar setups (switching LEDs) and learn how that's done.
$endgroup$
– Bimpelrekkie
13 hours ago
2
2
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
12 hours ago
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
12 hours ago
$begingroup$
0.2V isn't enough to run an LED; if you have a rail that'll drive an LED then you can use a comparator.
$endgroup$
– TimWescott
9 hours ago
$begingroup$
0.2V isn't enough to run an LED; if you have a rail that'll drive an LED then you can use a comparator.
$endgroup$
– TimWescott
9 hours ago
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
9 hours ago
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
9 hours ago
|
show 2 more comments
4 Answers
4
active
oldest
votes
$begingroup$
Whilst I'm inclined to agree with @Bimpelrekkie that this is probably an X-Y problem, for those who might actually need such a device there are some options. Most MOSFETs are sold as enhancement or depletion mode (less commonly) devices, however it's possible to tune the threshold voltage to approximately zero +/- tens of mV.
For example, the Advanced Linear Devices ALD110800A and similar devices in that series have a nominal zero gate threshold (1uA Ids). The subthreshold behavior is fairly well documented as well.
For your actual situation, use CrossRoads circuit with just about any single supply op-amp or single-supply comparator. LM358 or LM393 will work fine from a 5V supply.
answered 13 hours ago
Spehro PefhanySpehro Pefhany
213k5162432
$endgroup$
add a comment |
$begingroup$
No single transistor can do what you want. Instead, you need to use multiple transistors. A simple voltage comparator will do what you want:
simulate this circuit – Schematic created using CircuitLab
R2 and R3 set the reference voltage for the base of Q2. As long as the voltage at the base of Q1 is less than Vref, all of the current through R1 will flow through Q2. As soon as the input voltage rises above 0.2V, Q2 will cut off and all of the current will flow through Q1 and the LED instead.
Note that since the emitters of the transistors need to be at a negative voltage, this circuit requires a negative supply. An alternative would be to use an IC comparator — you can find single-supply units that can work with input voltages close to ground.
answered 13 hours ago
Dave Tweed♦Dave Tweed
123k10153267
$endgroup$
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
8 hours ago
$begingroup$
@RussellMcMahon: But then there's no overhead left for the load (LED), at least, not without adding additional transistors. At that point, just get the IC comparator, which is essentially the same thing.
$endgroup$
– Dave Tweed♦
8 hours ago
add a comment |
$begingroup$
simulate this circuit – Schematic created using CircuitLab
You could also use an Op Amp, or a Comparator. Set one input to 0.2V, when the other input exceeds that, the output will switch.
Here's one example
https://datasheets.maximintegrated.com/en/ds/MAX9107-MAX9109.pdf
edited 7 hours ago
Dave Tweed♦
123k10153267
answered 13 hours ago
CrossRoadsCrossRoads
2,11728
$endgroup$
add a comment |
$begingroup$
A well chosen germanium transistor can do this. I have some that switch at .15V. Finding one might be a problem ; I am not offering any of mine, but they still exist. If you need accurateness use one of the other answers, The simplest solution is to prebias a transistor so the base receives enough voltage to turn on when the input is .2V. I have used this trick in non-critical situations.
answered 13 mins ago
EinarAEinarA
1345
$endgroup$
add a comment |
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Whilst I'm inclined to agree with @Bimpelrekkie that this is probably an X-Y problem, for those who might actually need such a device there are some options. Most MOSFETs are sold as enhancement or depletion mode (less commonly) devices, however it's possible to tune the threshold voltage to approximately zero +/- tens of mV.
For example, the Advanced Linear Devices ALD110800A and similar devices in that series have a nominal zero gate threshold (1uA Ids). The subthreshold behavior is fairly well documented as well.
For your actual situation, use CrossRoads circuit with just about any single supply op-amp or single-supply comparator. LM358 or LM393 will work fine from a 5V supply.
answered 13 hours ago
Spehro PefhanySpehro Pefhany
213k5162432
$endgroup$
add a comment |
$begingroup$
Whilst I'm inclined to agree with @Bimpelrekkie that this is probably an X-Y problem, for those who might actually need such a device there are some options. Most MOSFETs are sold as enhancement or depletion mode (less commonly) devices, however it's possible to tune the threshold voltage to approximately zero +/- tens of mV.
For example, the Advanced Linear Devices ALD110800A and similar devices in that series have a nominal zero gate threshold (1uA Ids). The subthreshold behavior is fairly well documented as well.
For your actual situation, use CrossRoads circuit with just about any single supply op-amp or single-supply comparator. LM358 or LM393 will work fine from a 5V supply.
answered 13 hours ago
Spehro PefhanySpehro Pefhany
213k5162432
$endgroup$
add a comment |
$begingroup$
Whilst I'm inclined to agree with @Bimpelrekkie that this is probably an X-Y problem, for those who might actually need such a device there are some options. Most MOSFETs are sold as enhancement or depletion mode (less commonly) devices, however it's possible to tune the threshold voltage to approximately zero +/- tens of mV.
For example, the Advanced Linear Devices ALD110800A and similar devices in that series have a nominal zero gate threshold (1uA Ids). The subthreshold behavior is fairly well documented as well.
For your actual situation, use CrossRoads circuit with just about any single supply op-amp or single-supply comparator. LM358 or LM393 will work fine from a 5V supply.
answered 13 hours ago
Spehro PefhanySpehro Pefhany
213k5162432
$endgroup$
Whilst I'm inclined to agree with @Bimpelrekkie that this is probably an X-Y problem, for those who might actually need such a device there are some options. Most MOSFETs are sold as enhancement or depletion mode (less commonly) devices, however it's possible to tune the threshold voltage to approximately zero +/- tens of mV.
For example, the Advanced Linear Devices ALD110800A and similar devices in that series have a nominal zero gate threshold (1uA Ids). The subthreshold behavior is fairly well documented as well.
For your actual situation, use CrossRoads circuit with just about any single supply op-amp or single-supply comparator. LM358 or LM393 will work fine from a 5V supply.
answered 13 hours ago
Spehro PefhanySpehro Pefhany
213k5162432
edited 6 hours ago
answered 13 hours ago
Spehro PefhanySpehro Pefhany
213k5162432
answered 13 hours ago
Spehro PefhanySpehro Pefhany
213k5162432
answered 13 hours ago
Spehro PefhanySpehro Pefhany
213k5162432
213k5162432
add a comment |
add a comment |
$begingroup$
No single transistor can do what you want. Instead, you need to use multiple transistors. A simple voltage comparator will do what you want:
simulate this circuit – Schematic created using CircuitLab
R2 and R3 set the reference voltage for the base of Q2. As long as the voltage at the base of Q1 is less than Vref, all of the current through R1 will flow through Q2. As soon as the input voltage rises above 0.2V, Q2 will cut off and all of the current will flow through Q1 and the LED instead.
Note that since the emitters of the transistors need to be at a negative voltage, this circuit requires a negative supply. An alternative would be to use an IC comparator — you can find single-supply units that can work with input voltages close to ground.
answered 13 hours ago
Dave Tweed♦Dave Tweed
123k10153267
$endgroup$
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
8 hours ago
$begingroup$
@RussellMcMahon: But then there's no overhead left for the load (LED), at least, not without adding additional transistors. At that point, just get the IC comparator, which is essentially the same thing.
$endgroup$
– Dave Tweed♦
8 hours ago
add a comment |
$begingroup$
No single transistor can do what you want. Instead, you need to use multiple transistors. A simple voltage comparator will do what you want:
simulate this circuit – Schematic created using CircuitLab
R2 and R3 set the reference voltage for the base of Q2. As long as the voltage at the base of Q1 is less than Vref, all of the current through R1 will flow through Q2. As soon as the input voltage rises above 0.2V, Q2 will cut off and all of the current will flow through Q1 and the LED instead.
Note that since the emitters of the transistors need to be at a negative voltage, this circuit requires a negative supply. An alternative would be to use an IC comparator — you can find single-supply units that can work with input voltages close to ground.
answered 13 hours ago
Dave Tweed♦Dave Tweed
123k10153267
$endgroup$
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
8 hours ago
$begingroup$
@RussellMcMahon: But then there's no overhead left for the load (LED), at least, not without adding additional transistors. At that point, just get the IC comparator, which is essentially the same thing.
$endgroup$
– Dave Tweed♦
8 hours ago
add a comment |
$begingroup$
No single transistor can do what you want. Instead, you need to use multiple transistors. A simple voltage comparator will do what you want:
simulate this circuit – Schematic created using CircuitLab
R2 and R3 set the reference voltage for the base of Q2. As long as the voltage at the base of Q1 is less than Vref, all of the current through R1 will flow through Q2. As soon as the input voltage rises above 0.2V, Q2 will cut off and all of the current will flow through Q1 and the LED instead.
Note that since the emitters of the transistors need to be at a negative voltage, this circuit requires a negative supply. An alternative would be to use an IC comparator — you can find single-supply units that can work with input voltages close to ground.
answered 13 hours ago
Dave Tweed♦Dave Tweed
123k10153267
$endgroup$
No single transistor can do what you want. Instead, you need to use multiple transistors. A simple voltage comparator will do what you want:
simulate this circuit – Schematic created using CircuitLab
R2 and R3 set the reference voltage for the base of Q2. As long as the voltage at the base of Q1 is less than Vref, all of the current through R1 will flow through Q2. As soon as the input voltage rises above 0.2V, Q2 will cut off and all of the current will flow through Q1 and the LED instead.
Note that since the emitters of the transistors need to be at a negative voltage, this circuit requires a negative supply. An alternative would be to use an IC comparator — you can find single-supply units that can work with input voltages close to ground.
answered 13 hours ago
Dave Tweed♦Dave Tweed
123k10153267
answered 13 hours ago
Dave Tweed♦Dave Tweed
123k10153267
answered 13 hours ago
Dave Tweed♦Dave Tweed
123k10153267
answered 13 hours ago
Dave Tweed♦Dave Tweed
123k10153267
123k10153267
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
8 hours ago
$begingroup$
@RussellMcMahon: But then there's no overhead left for the load (LED), at least, not without adding additional transistors. At that point, just get the IC comparator, which is essentially the same thing.
$endgroup$
– Dave Tweed♦
8 hours ago
add a comment |
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
8 hours ago
$begingroup$
@RussellMcMahon: But then there's no overhead left for the load (LED), at least, not without adding additional transistors. At that point, just get the IC comparator, which is essentially the same thing.
$endgroup$
– Dave Tweed♦
8 hours ago
1
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
8 hours ago
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
8 hours ago
$begingroup$
@RussellMcMahon: But then there's no overhead left for the load (LED), at least, not without adding additional transistors. At that point, just get the IC comparator, which is essentially the same thing.
$endgroup$
– Dave Tweed♦
8 hours ago
$begingroup$
@RussellMcMahon: But then there's no overhead left for the load (LED), at least, not without adding additional transistors. At that point, just get the IC comparator, which is essentially the same thing.
$endgroup$
– Dave Tweed♦
8 hours ago
add a comment |
$begingroup$
simulate this circuit – Schematic created using CircuitLab
You could also use an Op Amp, or a Comparator. Set one input to 0.2V, when the other input exceeds that, the output will switch.
Here's one example
https://datasheets.maximintegrated.com/en/ds/MAX9107-MAX9109.pdf
edited 7 hours ago
Dave Tweed♦
123k10153267
answered 13 hours ago
CrossRoadsCrossRoads
2,11728
$endgroup$
add a comment |
$begingroup$
simulate this circuit – Schematic created using CircuitLab
You could also use an Op Amp, or a Comparator. Set one input to 0.2V, when the other input exceeds that, the output will switch.
Here's one example
https://datasheets.maximintegrated.com/en/ds/MAX9107-MAX9109.pdf
edited 7 hours ago
Dave Tweed♦
123k10153267
answered 13 hours ago
CrossRoadsCrossRoads
2,11728
$endgroup$
add a comment |
$begingroup$
simulate this circuit – Schematic created using CircuitLab
You could also use an Op Amp, or a Comparator. Set one input to 0.2V, when the other input exceeds that, the output will switch.
Here's one example
https://datasheets.maximintegrated.com/en/ds/MAX9107-MAX9109.pdf
edited 7 hours ago
Dave Tweed♦
123k10153267
answered 13 hours ago
CrossRoadsCrossRoads
2,11728
$endgroup$
simulate this circuit – Schematic created using CircuitLab
You could also use an Op Amp, or a Comparator. Set one input to 0.2V, when the other input exceeds that, the output will switch.
Here's one example
https://datasheets.maximintegrated.com/en/ds/MAX9107-MAX9109.pdf
edited 7 hours ago
Dave Tweed♦
123k10153267
answered 13 hours ago
CrossRoadsCrossRoads
2,11728
edited 7 hours ago
Dave Tweed♦
123k10153267
edited 7 hours ago
Dave Tweed♦
123k10153267
edited 7 hours ago
Dave Tweed♦
123k10153267
123k10153267
answered 13 hours ago
CrossRoadsCrossRoads
2,11728
answered 13 hours ago
CrossRoadsCrossRoads
2,11728
answered 13 hours ago
CrossRoadsCrossRoads
2,11728
2,11728
add a comment |
add a comment |
$begingroup$
A well chosen germanium transistor can do this. I have some that switch at .15V. Finding one might be a problem ; I am not offering any of mine, but they still exist. If you need accurateness use one of the other answers, The simplest solution is to prebias a transistor so the base receives enough voltage to turn on when the input is .2V. I have used this trick in non-critical situations.
answered 13 mins ago
EinarAEinarA
1345
$endgroup$
add a comment |
$begingroup$
A well chosen germanium transistor can do this. I have some that switch at .15V. Finding one might be a problem ; I am not offering any of mine, but they still exist. If you need accurateness use one of the other answers, The simplest solution is to prebias a transistor so the base receives enough voltage to turn on when the input is .2V. I have used this trick in non-critical situations.
answered 13 mins ago
EinarAEinarA
1345
$endgroup$
add a comment |
$begingroup$
A well chosen germanium transistor can do this. I have some that switch at .15V. Finding one might be a problem ; I am not offering any of mine, but they still exist. If you need accurateness use one of the other answers, The simplest solution is to prebias a transistor so the base receives enough voltage to turn on when the input is .2V. I have used this trick in non-critical situations.
answered 13 mins ago
EinarAEinarA
1345
$endgroup$
A well chosen germanium transistor can do this. I have some that switch at .15V. Finding one might be a problem ; I am not offering any of mine, but they still exist. If you need accurateness use one of the other answers, The simplest solution is to prebias a transistor so the base receives enough voltage to turn on when the input is .2V. I have used this trick in non-critical situations.
answered 13 mins ago
EinarAEinarA
1345
answered 13 mins ago
EinarAEinarA
1345
answered 13 mins ago
EinarAEinarA
1345
answered 13 mins ago
EinarAEinarA
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seyyedali hosseini is a new contributor. Be nice, and check out our Code of Conduct.
seyyedali hosseini is a new contributor. Be nice, and check out our Code of Conduct.
seyyedali hosseini is a new contributor. Be nice, and check out our Code of Conduct.
seyyedali hosseini is a new contributor. Be nice, and check out our Code of Conduct.
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5
$begingroup$
Pretty much none of them. I would recommend amplifying the signal before trying to use it as a switch, perhaps with a comparator.
$endgroup$
– Hearth
13 hours ago
5
$begingroup$
Instead of asking about a transistor which needs to turn on with only 0.2 V (there aren't any but please prove me wrong!) and assume that you can do this with only one transistor (you can't but I'd like to be proven wrong again), describe what your requirements are and ask what solutions exist. A LED will not light up with 0.2 V so there must be some other voltage present. Why 0.2 V? Do research on similar setups (switching LEDs) and learn how that's done.
$endgroup$
– Bimpelrekkie
13 hours ago
2
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
12 hours ago
$begingroup$
0.2V isn't enough to run an LED; if you have a rail that'll drive an LED then you can use a comparator.
$endgroup$
– TimWescott
9 hours ago
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
9 hours ago