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What kind of transistor turns on with 0.2 volts?
Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)Using transistor as switch with low voltageWhat type of transistor would be required?Simple transistor circuit with unconnected gate pin acts strangelyTurn off an always on led with transistorTurning on LED panel with a NPN transistorWhat kind of transistor do I use for switching high voltage with a microcontroller?switch a PN2222 transistor at 18 volts, with variable 0 to 30 volts inputIs there any 'switching IC' to replace 'transistor switch' for switching the 12 volts LED array?What is a 0118 transistor?how to switch dc motor with transistor?Turns 12 volts DC to 60 volts DC with 2mA
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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 Apr 8 at 12:01
seyyedali hosseiniseyyedali hosseini
173
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.
$endgroup$
|
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 Apr 8 at 12:01
seyyedali hosseiniseyyedali hosseini
173
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
Apr 8 at 12:04
6
$begingroup$
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
Apr 8 at 12:11
2
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
Apr 8 at 13:00
$begingroup$
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
Apr 8 at 15:54
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
Apr 8 at 16:21
|
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 Apr 8 at 12:01
seyyedali hosseiniseyyedali hosseini
173
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 Apr 8 at 12:01
seyyedali hosseiniseyyedali hosseini
173
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 Apr 8 at 12:01
seyyedali hosseiniseyyedali hosseini
173
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 Apr 8 at 12:01
seyyedali hosseiniseyyedali hosseini
173
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 Apr 8 at 12:01
seyyedali hosseiniseyyedali hosseini
173
asked Apr 8 at 12:01
seyyedali hosseiniseyyedali hosseini
173
173
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
Apr 8 at 12:04
6
$begingroup$
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
Apr 8 at 12:11
2
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
Apr 8 at 13:00
$begingroup$
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
Apr 8 at 15:54
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
Apr 8 at 16:21
|
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
Apr 8 at 12:04
6
$begingroup$
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
Apr 8 at 12:11
2
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
Apr 8 at 13:00
$begingroup$
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
Apr 8 at 15:54
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
Apr 8 at 16:21
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
Apr 8 at 12:04
$begingroup$
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
Apr 8 at 12:04
6
6
$begingroup$
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
Apr 8 at 12:11
$begingroup$
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
Apr 8 at 12:11
2
2
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
Apr 8 at 13:00
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
Apr 8 at 13:00
$begingroup$
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
Apr 8 at 15:54
$begingroup$
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
Apr 8 at 15:54
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
Apr 8 at 16:21
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
Apr 8 at 16:21
|
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 Apr 8 at 12:28
Spehro PefhanySpehro Pefhany
214k5162433
$endgroup$
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 Apr 8 at 12:23
Dave Tweed♦Dave Tweed
125k10154269
$endgroup$
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
Apr 8 at 17:34
$begingroup$
@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♦
Apr 8 at 17:36
$begingroup$
This circuit really needs some positive feedback to achieve a clean switch.
$endgroup$
– EinarA
Apr 9 at 7:17
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 Apr 8 at 17:46
Dave Tweed♦
125k10154269
answered Apr 8 at 12:42
CrossRoadsCrossRoads
2,12628
$endgroup$
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 Apr 9 at 1:31
EinarAEinarA
1525
$endgroup$
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 Apr 8 at 12:28
Spehro PefhanySpehro Pefhany
214k5162433
$endgroup$
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 Apr 8 at 12:28
Spehro PefhanySpehro Pefhany
214k5162433
$endgroup$
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 Apr 8 at 12:28
Spehro PefhanySpehro Pefhany
214k5162433
$endgroup$
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 Apr 8 at 12:28
Spehro PefhanySpehro Pefhany
214k5162433
edited Apr 8 at 18:50
answered Apr 8 at 12:28
Spehro PefhanySpehro Pefhany
214k5162433
answered Apr 8 at 12:28
Spehro PefhanySpehro Pefhany
214k5162433
answered Apr 8 at 12:28
Spehro PefhanySpehro Pefhany
214k5162433
214k5162433
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 Apr 8 at 12:23
Dave Tweed♦Dave Tweed
125k10154269
$endgroup$
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
Apr 8 at 17:34
$begingroup$
@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♦
Apr 8 at 17:36
$begingroup$
This circuit really needs some positive feedback to achieve a clean switch.
$endgroup$
– EinarA
Apr 9 at 7:17
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 Apr 8 at 12:23
Dave Tweed♦Dave Tweed
125k10154269
$endgroup$
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
Apr 8 at 17:34
$begingroup$
@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♦
Apr 8 at 17:36
$begingroup$
This circuit really needs some positive feedback to achieve a clean switch.
$endgroup$
– EinarA
Apr 9 at 7:17
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 Apr 8 at 12:23
Dave Tweed♦Dave Tweed
125k10154269
$endgroup$
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 Apr 8 at 12:23
Dave Tweed♦Dave Tweed
125k10154269
answered Apr 8 at 12:23
Dave Tweed♦Dave Tweed
125k10154269
answered Apr 8 at 12:23
Dave Tweed♦Dave Tweed
125k10154269
answered Apr 8 at 12:23
Dave Tweed♦Dave Tweed
125k10154269
125k10154269
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
Apr 8 at 17:34
$begingroup$
@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♦
Apr 8 at 17:36
$begingroup$
This circuit really needs some positive feedback to achieve a clean switch.
$endgroup$
– EinarA
Apr 9 at 7:17
add a comment |
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
Apr 8 at 17:34
$begingroup$
@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♦
Apr 8 at 17:36
$begingroup$
This circuit really needs some positive feedback to achieve a clean switch.
$endgroup$
– EinarA
Apr 9 at 7:17
1
1
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
Apr 8 at 17:34
$begingroup$
You can approach the lower rail by using PNPs 'upside down' and a single supply.
$endgroup$
– Russell McMahon
Apr 8 at 17:34
$begingroup$
@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♦
Apr 8 at 17:36
$begingroup$
@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♦
Apr 8 at 17:36
$begingroup$
This circuit really needs some positive feedback to achieve a clean switch.
$endgroup$
– EinarA
Apr 9 at 7:17
$begingroup$
This circuit really needs some positive feedback to achieve a clean switch.
$endgroup$
– EinarA
Apr 9 at 7:17
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 Apr 8 at 17:46
Dave Tweed♦
125k10154269
answered Apr 8 at 12:42
CrossRoadsCrossRoads
2,12628
$endgroup$
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 Apr 8 at 17:46
Dave Tweed♦
125k10154269
answered Apr 8 at 12:42
CrossRoadsCrossRoads
2,12628
$endgroup$
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 Apr 8 at 17:46
Dave Tweed♦
125k10154269
answered Apr 8 at 12:42
CrossRoadsCrossRoads
2,12628
$endgroup$
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 Apr 8 at 17:46
Dave Tweed♦
125k10154269
answered Apr 8 at 12:42
CrossRoadsCrossRoads
2,12628
edited Apr 8 at 17:46
Dave Tweed♦
125k10154269
edited Apr 8 at 17:46
Dave Tweed♦
125k10154269
edited Apr 8 at 17:46
Dave Tweed♦
125k10154269
125k10154269
answered Apr 8 at 12:42
CrossRoadsCrossRoads
2,12628
answered Apr 8 at 12:42
CrossRoadsCrossRoads
2,12628
answered Apr 8 at 12:42
CrossRoadsCrossRoads
2,12628
2,12628
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 Apr 9 at 1:31
EinarAEinarA
1525
$endgroup$
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 Apr 9 at 1:31
EinarAEinarA
1525
$endgroup$
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 Apr 9 at 1:31
EinarAEinarA
1525
$endgroup$
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 Apr 9 at 1:31
EinarAEinarA
1525
answered Apr 9 at 1:31
EinarAEinarA
1525
answered Apr 9 at 1:31
EinarAEinarA
1525
answered Apr 9 at 1:31
EinarAEinarA
1525
1525
add a comment |
add a comment |
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
Apr 8 at 12:04
6
$begingroup$
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
Apr 8 at 12:11
2
$begingroup$
Highly related if not duplicate: electronics.stackexchange.com/questions/129183/…
$endgroup$
– winny
Apr 8 at 13:00
$begingroup$
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
Apr 8 at 15:54
$begingroup$
What's the LED and what's the current and voltage it requires? What power supply rails do you have?
$endgroup$
– jonk
Apr 8 at 16:21