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What happens in the secondary winding if there's no spark plug connected?
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}
$begingroup$
The circuit below (minus the transformer and SCR) is used to detect the existence of a flame using the concept of flame rectification. Based on the circuit here: Pilot Light Flame Sensor
I have already proven this out, and it works awesome. Instead of the probe used in the link above, I chose to use a spark plug. This was done on purpose, as now I would like to add a spark transformer to automatically light the flame. So, now the spark plug will be used not only for sensing the flame, but for ignition as well.
I added in a spark transformer (1:1000) and SCR to my diagram as an initial concept, but have some concerns:
1) When the spark is activated, it will be in the 10kV range. Could this damage my sensing circuit, or will the high voltage only be seen at the spark gap? Maybe I need a zener diode or TVS at the input of my sensing circuit?
2) If the voltage isn't able to jump the gap and spark (if the spark plug wasn't functioning properly or pulled out of the circuit), what happens to the energy? Would this end up damaging my sensing circuit?
PULSE: This is a pulse coming from an audio transformer on another page. This is essential to the sensing circuit from the link above.
SPARK: This is a signal from a microcontroller to initiate ignition.
transformer automotive
asked 6 hours ago
gtetilgtetil
214
$endgroup$
add a comment |
$begingroup$
The circuit below (minus the transformer and SCR) is used to detect the existence of a flame using the concept of flame rectification. Based on the circuit here: Pilot Light Flame Sensor
I have already proven this out, and it works awesome. Instead of the probe used in the link above, I chose to use a spark plug. This was done on purpose, as now I would like to add a spark transformer to automatically light the flame. So, now the spark plug will be used not only for sensing the flame, but for ignition as well.
I added in a spark transformer (1:1000) and SCR to my diagram as an initial concept, but have some concerns:
1) When the spark is activated, it will be in the 10kV range. Could this damage my sensing circuit, or will the high voltage only be seen at the spark gap? Maybe I need a zener diode or TVS at the input of my sensing circuit?
2) If the voltage isn't able to jump the gap and spark (if the spark plug wasn't functioning properly or pulled out of the circuit), what happens to the energy? Would this end up damaging my sensing circuit?
PULSE: This is a pulse coming from an audio transformer on another page. This is essential to the sensing circuit from the link above.
SPARK: This is a signal from a microcontroller to initiate ignition.
transformer automotive
asked 6 hours ago
gtetilgtetil
214
$endgroup$
$begingroup$
1) "Could this damage my sensing circuit" - Most likely. 2) "Would this end up damaging my sensing circuit?" - Definitely. Apart from the strong EMI, you will have to provide enough insulation for the high voltage, esp. R14 and R10 must not arc/break in the presence of ~10kV. I suggest you disconnect the sensing circuit via a relay or something during the time the ingition procedure runs.
$endgroup$
– JimmyB
6 hours ago
2
$begingroup$
How do you turn your SCR off again?
$endgroup$
– Finbarr
6 hours ago
$begingroup$
If this was me I would use 2 spark plugs. This is a known method of ignition and flame detection because it is simpler that way. High energy discharges and sensitive input circuitry do not make good bedfellows.
$endgroup$
– KalleMP
3 hours ago
add a comment |
$begingroup$
The circuit below (minus the transformer and SCR) is used to detect the existence of a flame using the concept of flame rectification. Based on the circuit here: Pilot Light Flame Sensor
I have already proven this out, and it works awesome. Instead of the probe used in the link above, I chose to use a spark plug. This was done on purpose, as now I would like to add a spark transformer to automatically light the flame. So, now the spark plug will be used not only for sensing the flame, but for ignition as well.
I added in a spark transformer (1:1000) and SCR to my diagram as an initial concept, but have some concerns:
1) When the spark is activated, it will be in the 10kV range. Could this damage my sensing circuit, or will the high voltage only be seen at the spark gap? Maybe I need a zener diode or TVS at the input of my sensing circuit?
2) If the voltage isn't able to jump the gap and spark (if the spark plug wasn't functioning properly or pulled out of the circuit), what happens to the energy? Would this end up damaging my sensing circuit?
PULSE: This is a pulse coming from an audio transformer on another page. This is essential to the sensing circuit from the link above.
SPARK: This is a signal from a microcontroller to initiate ignition.
transformer automotive
asked 6 hours ago
gtetilgtetil
214
$endgroup$
The circuit below (minus the transformer and SCR) is used to detect the existence of a flame using the concept of flame rectification. Based on the circuit here: Pilot Light Flame Sensor
I have already proven this out, and it works awesome. Instead of the probe used in the link above, I chose to use a spark plug. This was done on purpose, as now I would like to add a spark transformer to automatically light the flame. So, now the spark plug will be used not only for sensing the flame, but for ignition as well.
I added in a spark transformer (1:1000) and SCR to my diagram as an initial concept, but have some concerns:
1) When the spark is activated, it will be in the 10kV range. Could this damage my sensing circuit, or will the high voltage only be seen at the spark gap? Maybe I need a zener diode or TVS at the input of my sensing circuit?
2) If the voltage isn't able to jump the gap and spark (if the spark plug wasn't functioning properly or pulled out of the circuit), what happens to the energy? Would this end up damaging my sensing circuit?
PULSE: This is a pulse coming from an audio transformer on another page. This is essential to the sensing circuit from the link above.
SPARK: This is a signal from a microcontroller to initiate ignition.
transformer automotive
transformer automotive
asked 6 hours ago
gtetilgtetil
214
asked 6 hours ago
gtetilgtetil
214
asked 6 hours ago
gtetilgtetil
214
asked 6 hours ago
gtetilgtetil
214
asked 6 hours ago
gtetilgtetil
214
214
$begingroup$
1) "Could this damage my sensing circuit" - Most likely. 2) "Would this end up damaging my sensing circuit?" - Definitely. Apart from the strong EMI, you will have to provide enough insulation for the high voltage, esp. R14 and R10 must not arc/break in the presence of ~10kV. I suggest you disconnect the sensing circuit via a relay or something during the time the ingition procedure runs.
$endgroup$
– JimmyB
6 hours ago
2
$begingroup$
How do you turn your SCR off again?
$endgroup$
– Finbarr
6 hours ago
$begingroup$
If this was me I would use 2 spark plugs. This is a known method of ignition and flame detection because it is simpler that way. High energy discharges and sensitive input circuitry do not make good bedfellows.
$endgroup$
– KalleMP
3 hours ago
add a comment |
$begingroup$
1) "Could this damage my sensing circuit" - Most likely. 2) "Would this end up damaging my sensing circuit?" - Definitely. Apart from the strong EMI, you will have to provide enough insulation for the high voltage, esp. R14 and R10 must not arc/break in the presence of ~10kV. I suggest you disconnect the sensing circuit via a relay or something during the time the ingition procedure runs.
$endgroup$
– JimmyB
6 hours ago
2
$begingroup$
How do you turn your SCR off again?
$endgroup$
– Finbarr
6 hours ago
$begingroup$
If this was me I would use 2 spark plugs. This is a known method of ignition and flame detection because it is simpler that way. High energy discharges and sensitive input circuitry do not make good bedfellows.
$endgroup$
– KalleMP
3 hours ago
$begingroup$
1) "Could this damage my sensing circuit" - Most likely. 2) "Would this end up damaging my sensing circuit?" - Definitely. Apart from the strong EMI, you will have to provide enough insulation for the high voltage, esp. R14 and R10 must not arc/break in the presence of ~10kV. I suggest you disconnect the sensing circuit via a relay or something during the time the ingition procedure runs.
$endgroup$
– JimmyB
6 hours ago
$begingroup$
1) "Could this damage my sensing circuit" - Most likely. 2) "Would this end up damaging my sensing circuit?" - Definitely. Apart from the strong EMI, you will have to provide enough insulation for the high voltage, esp. R14 and R10 must not arc/break in the presence of ~10kV. I suggest you disconnect the sensing circuit via a relay or something during the time the ingition procedure runs.
$endgroup$
– JimmyB
6 hours ago
2
2
$begingroup$
How do you turn your SCR off again?
$endgroup$
– Finbarr
6 hours ago
$begingroup$
How do you turn your SCR off again?
$endgroup$
– Finbarr
6 hours ago
$begingroup$
If this was me I would use 2 spark plugs. This is a known method of ignition and flame detection because it is simpler that way. High energy discharges and sensitive input circuitry do not make good bedfellows.
$endgroup$
– KalleMP
3 hours ago
$begingroup$
If this was me I would use 2 spark plugs. This is a known method of ignition and flame detection because it is simpler that way. High energy discharges and sensitive input circuitry do not make good bedfellows.
$endgroup$
– KalleMP
3 hours ago
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
Could this damage my sensing circuit. – YES.
You have to ground pin 3 of your transformer before firing the spark. A relay will do the trick. Other electronics, not so much.
answered 6 hours ago
JankaJanka
8,7771921
$endgroup$
$begingroup$
Good idea, but would the relay contacts see the 10kV? Most mechanical relays only have a rating up to 480V at the most.
$endgroup$
– gtetil
6 hours ago
3
$begingroup$
You activate the relay (you could also use a MOSFET) before you generate the spark. No high voltage appears across the relay contacts, because they are closed. You need this path anyway for the spark current; otherwise, the only other path is through the 3M resistor.
$endgroup$
– Dave Tweed♦
5 hours ago
$begingroup$
@gtetil Relay contacts can withstand 10kV, but they are very expensive. No small relay will withstand this voltage since they rely purely on air gap. You have to use a vacuum contact chamber to provide this sort of capability. An example here: te.com/commerce/DocumentDelivery/…
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
@janka Please suggest relay with capability that is not really really expensive
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
What @DaveTweed said. You would use a fairly generic relay but test the contact continuity with a current source before firing the spark to make sure your circuit is protected.
$endgroup$
– KalleMP
3 hours ago
|
show 1 more comment
$begingroup$
What happens under fault conditions with the 10kV transformer generator?
While I doubt that you would destroy Q1 or U1A you have several problem conditions for your circuit.
The SCR only turns off if you get resonance on the output transformer (which I assume is NOT an ignition coil). If the output ever becomes short, then the SCR won't turn off and you may well have a problem.
If (as in the link you posted) you use a conventional transformer to generate the high voltage, you will likely see arc inside the transformer if the output is open circuit. You could Hipot test your transformer, but I think you'll be disappointed in the results. You should use an ignition coil such as this, they are cheap and withstand >25kV.
If the output (spark side) is shorted then terminal (3) becomes the output. Again I don't think you'll damage Q1 (saved by C14) but you are definitely outside your design parameters.
Suggestions:
Use an ignition coil to produce the high voltage. This will change your circuit since it's only a three terminal device.
Replace the SCR with a high voltage FET. You can still drive the common point of the ignition where convention is that the primary and secondary are in series for spark production. You have to deal with the complexity of when you produce the spark or the sensing voltage. If the primary is kept energized and you turn OFF the FET you'll produce a spark (20kV). If the primary is not energized and you turn the FET ON, then you'll produce a much smaller voltage (2kV).
Put a series resistor in the primary winding to set the maximum current flow for the transformer.
Put a series diode in the high voltage transformer output so only the positive peaks reach the spark plug.
Connect your sensing resistor to the transformer output (your spark plug tip). It needs to be a high voltage resistor.
answered 5 hours ago
Jack CreaseyJack Creasey
15.5k2823
$endgroup$
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Could this damage my sensing circuit. – YES.
You have to ground pin 3 of your transformer before firing the spark. A relay will do the trick. Other electronics, not so much.
answered 6 hours ago
JankaJanka
8,7771921
$endgroup$
$begingroup$
Good idea, but would the relay contacts see the 10kV? Most mechanical relays only have a rating up to 480V at the most.
$endgroup$
– gtetil
6 hours ago
3
$begingroup$
You activate the relay (you could also use a MOSFET) before you generate the spark. No high voltage appears across the relay contacts, because they are closed. You need this path anyway for the spark current; otherwise, the only other path is through the 3M resistor.
$endgroup$
– Dave Tweed♦
5 hours ago
$begingroup$
@gtetil Relay contacts can withstand 10kV, but they are very expensive. No small relay will withstand this voltage since they rely purely on air gap. You have to use a vacuum contact chamber to provide this sort of capability. An example here: te.com/commerce/DocumentDelivery/…
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
@janka Please suggest relay with capability that is not really really expensive
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
What @DaveTweed said. You would use a fairly generic relay but test the contact continuity with a current source before firing the spark to make sure your circuit is protected.
$endgroup$
– KalleMP
3 hours ago
|
show 1 more comment
$begingroup$
Could this damage my sensing circuit. – YES.
You have to ground pin 3 of your transformer before firing the spark. A relay will do the trick. Other electronics, not so much.
answered 6 hours ago
JankaJanka
8,7771921
$endgroup$
$begingroup$
Good idea, but would the relay contacts see the 10kV? Most mechanical relays only have a rating up to 480V at the most.
$endgroup$
– gtetil
6 hours ago
3
$begingroup$
You activate the relay (you could also use a MOSFET) before you generate the spark. No high voltage appears across the relay contacts, because they are closed. You need this path anyway for the spark current; otherwise, the only other path is through the 3M resistor.
$endgroup$
– Dave Tweed♦
5 hours ago
$begingroup$
@gtetil Relay contacts can withstand 10kV, but they are very expensive. No small relay will withstand this voltage since they rely purely on air gap. You have to use a vacuum contact chamber to provide this sort of capability. An example here: te.com/commerce/DocumentDelivery/…
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
@janka Please suggest relay with capability that is not really really expensive
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
What @DaveTweed said. You would use a fairly generic relay but test the contact continuity with a current source before firing the spark to make sure your circuit is protected.
$endgroup$
– KalleMP
3 hours ago
|
show 1 more comment
$begingroup$
Could this damage my sensing circuit. – YES.
You have to ground pin 3 of your transformer before firing the spark. A relay will do the trick. Other electronics, not so much.
answered 6 hours ago
JankaJanka
8,7771921
$endgroup$
Could this damage my sensing circuit. – YES.
You have to ground pin 3 of your transformer before firing the spark. A relay will do the trick. Other electronics, not so much.
answered 6 hours ago
JankaJanka
8,7771921
answered 6 hours ago
JankaJanka
8,7771921
answered 6 hours ago
JankaJanka
8,7771921
answered 6 hours ago
JankaJanka
8,7771921
8,7771921
$begingroup$
Good idea, but would the relay contacts see the 10kV? Most mechanical relays only have a rating up to 480V at the most.
$endgroup$
– gtetil
6 hours ago
3
$begingroup$
You activate the relay (you could also use a MOSFET) before you generate the spark. No high voltage appears across the relay contacts, because they are closed. You need this path anyway for the spark current; otherwise, the only other path is through the 3M resistor.
$endgroup$
– Dave Tweed♦
5 hours ago
$begingroup$
@gtetil Relay contacts can withstand 10kV, but they are very expensive. No small relay will withstand this voltage since they rely purely on air gap. You have to use a vacuum contact chamber to provide this sort of capability. An example here: te.com/commerce/DocumentDelivery/…
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
@janka Please suggest relay with capability that is not really really expensive
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
What @DaveTweed said. You would use a fairly generic relay but test the contact continuity with a current source before firing the spark to make sure your circuit is protected.
$endgroup$
– KalleMP
3 hours ago
|
show 1 more comment
$begingroup$
Good idea, but would the relay contacts see the 10kV? Most mechanical relays only have a rating up to 480V at the most.
$endgroup$
– gtetil
6 hours ago
3
$begingroup$
You activate the relay (you could also use a MOSFET) before you generate the spark. No high voltage appears across the relay contacts, because they are closed. You need this path anyway for the spark current; otherwise, the only other path is through the 3M resistor.
$endgroup$
– Dave Tweed♦
5 hours ago
$begingroup$
@gtetil Relay contacts can withstand 10kV, but they are very expensive. No small relay will withstand this voltage since they rely purely on air gap. You have to use a vacuum contact chamber to provide this sort of capability. An example here: te.com/commerce/DocumentDelivery/…
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
@janka Please suggest relay with capability that is not really really expensive
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
What @DaveTweed said. You would use a fairly generic relay but test the contact continuity with a current source before firing the spark to make sure your circuit is protected.
$endgroup$
– KalleMP
3 hours ago
$begingroup$
Good idea, but would the relay contacts see the 10kV? Most mechanical relays only have a rating up to 480V at the most.
$endgroup$
– gtetil
6 hours ago
$begingroup$
Good idea, but would the relay contacts see the 10kV? Most mechanical relays only have a rating up to 480V at the most.
$endgroup$
– gtetil
6 hours ago
3
3
$begingroup$
You activate the relay (you could also use a MOSFET) before you generate the spark. No high voltage appears across the relay contacts, because they are closed. You need this path anyway for the spark current; otherwise, the only other path is through the 3M resistor.
$endgroup$
– Dave Tweed♦
5 hours ago
$begingroup$
You activate the relay (you could also use a MOSFET) before you generate the spark. No high voltage appears across the relay contacts, because they are closed. You need this path anyway for the spark current; otherwise, the only other path is through the 3M resistor.
$endgroup$
– Dave Tweed♦
5 hours ago
$begingroup$
@gtetil Relay contacts can withstand 10kV, but they are very expensive. No small relay will withstand this voltage since they rely purely on air gap. You have to use a vacuum contact chamber to provide this sort of capability. An example here: te.com/commerce/DocumentDelivery/…
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
@gtetil Relay contacts can withstand 10kV, but they are very expensive. No small relay will withstand this voltage since they rely purely on air gap. You have to use a vacuum contact chamber to provide this sort of capability. An example here: te.com/commerce/DocumentDelivery/…
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
@janka Please suggest relay with capability that is not really really expensive
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
@janka Please suggest relay with capability that is not really really expensive
$endgroup$
– Jack Creasey
4 hours ago
$begingroup$
What @DaveTweed said. You would use a fairly generic relay but test the contact continuity with a current source before firing the spark to make sure your circuit is protected.
$endgroup$
– KalleMP
3 hours ago
$begingroup$
What @DaveTweed said. You would use a fairly generic relay but test the contact continuity with a current source before firing the spark to make sure your circuit is protected.
$endgroup$
– KalleMP
3 hours ago
|
show 1 more comment
$begingroup$
What happens under fault conditions with the 10kV transformer generator?
While I doubt that you would destroy Q1 or U1A you have several problem conditions for your circuit.
The SCR only turns off if you get resonance on the output transformer (which I assume is NOT an ignition coil). If the output ever becomes short, then the SCR won't turn off and you may well have a problem.
If (as in the link you posted) you use a conventional transformer to generate the high voltage, you will likely see arc inside the transformer if the output is open circuit. You could Hipot test your transformer, but I think you'll be disappointed in the results. You should use an ignition coil such as this, they are cheap and withstand >25kV.
If the output (spark side) is shorted then terminal (3) becomes the output. Again I don't think you'll damage Q1 (saved by C14) but you are definitely outside your design parameters.
Suggestions:
Use an ignition coil to produce the high voltage. This will change your circuit since it's only a three terminal device.
Replace the SCR with a high voltage FET. You can still drive the common point of the ignition where convention is that the primary and secondary are in series for spark production. You have to deal with the complexity of when you produce the spark or the sensing voltage. If the primary is kept energized and you turn OFF the FET you'll produce a spark (20kV). If the primary is not energized and you turn the FET ON, then you'll produce a much smaller voltage (2kV).
Put a series resistor in the primary winding to set the maximum current flow for the transformer.
Put a series diode in the high voltage transformer output so only the positive peaks reach the spark plug.
Connect your sensing resistor to the transformer output (your spark plug tip). It needs to be a high voltage resistor.
answered 5 hours ago
Jack CreaseyJack Creasey
15.5k2823
$endgroup$
add a comment |
$begingroup$
What happens under fault conditions with the 10kV transformer generator?
While I doubt that you would destroy Q1 or U1A you have several problem conditions for your circuit.
The SCR only turns off if you get resonance on the output transformer (which I assume is NOT an ignition coil). If the output ever becomes short, then the SCR won't turn off and you may well have a problem.
If (as in the link you posted) you use a conventional transformer to generate the high voltage, you will likely see arc inside the transformer if the output is open circuit. You could Hipot test your transformer, but I think you'll be disappointed in the results. You should use an ignition coil such as this, they are cheap and withstand >25kV.
If the output (spark side) is shorted then terminal (3) becomes the output. Again I don't think you'll damage Q1 (saved by C14) but you are definitely outside your design parameters.
Suggestions:
Use an ignition coil to produce the high voltage. This will change your circuit since it's only a three terminal device.
Replace the SCR with a high voltage FET. You can still drive the common point of the ignition where convention is that the primary and secondary are in series for spark production. You have to deal with the complexity of when you produce the spark or the sensing voltage. If the primary is kept energized and you turn OFF the FET you'll produce a spark (20kV). If the primary is not energized and you turn the FET ON, then you'll produce a much smaller voltage (2kV).
Put a series resistor in the primary winding to set the maximum current flow for the transformer.
Put a series diode in the high voltage transformer output so only the positive peaks reach the spark plug.
Connect your sensing resistor to the transformer output (your spark plug tip). It needs to be a high voltage resistor.
answered 5 hours ago
Jack CreaseyJack Creasey
15.5k2823
$endgroup$
add a comment |
$begingroup$
What happens under fault conditions with the 10kV transformer generator?
While I doubt that you would destroy Q1 or U1A you have several problem conditions for your circuit.
The SCR only turns off if you get resonance on the output transformer (which I assume is NOT an ignition coil). If the output ever becomes short, then the SCR won't turn off and you may well have a problem.
If (as in the link you posted) you use a conventional transformer to generate the high voltage, you will likely see arc inside the transformer if the output is open circuit. You could Hipot test your transformer, but I think you'll be disappointed in the results. You should use an ignition coil such as this, they are cheap and withstand >25kV.
If the output (spark side) is shorted then terminal (3) becomes the output. Again I don't think you'll damage Q1 (saved by C14) but you are definitely outside your design parameters.
Suggestions:
Use an ignition coil to produce the high voltage. This will change your circuit since it's only a three terminal device.
Replace the SCR with a high voltage FET. You can still drive the common point of the ignition where convention is that the primary and secondary are in series for spark production. You have to deal with the complexity of when you produce the spark or the sensing voltage. If the primary is kept energized and you turn OFF the FET you'll produce a spark (20kV). If the primary is not energized and you turn the FET ON, then you'll produce a much smaller voltage (2kV).
Put a series resistor in the primary winding to set the maximum current flow for the transformer.
Put a series diode in the high voltage transformer output so only the positive peaks reach the spark plug.
Connect your sensing resistor to the transformer output (your spark plug tip). It needs to be a high voltage resistor.
answered 5 hours ago
Jack CreaseyJack Creasey
15.5k2823
$endgroup$
What happens under fault conditions with the 10kV transformer generator?
While I doubt that you would destroy Q1 or U1A you have several problem conditions for your circuit.
The SCR only turns off if you get resonance on the output transformer (which I assume is NOT an ignition coil). If the output ever becomes short, then the SCR won't turn off and you may well have a problem.
If (as in the link you posted) you use a conventional transformer to generate the high voltage, you will likely see arc inside the transformer if the output is open circuit. You could Hipot test your transformer, but I think you'll be disappointed in the results. You should use an ignition coil such as this, they are cheap and withstand >25kV.
If the output (spark side) is shorted then terminal (3) becomes the output. Again I don't think you'll damage Q1 (saved by C14) but you are definitely outside your design parameters.
Suggestions:
Use an ignition coil to produce the high voltage. This will change your circuit since it's only a three terminal device.
Replace the SCR with a high voltage FET. You can still drive the common point of the ignition where convention is that the primary and secondary are in series for spark production. You have to deal with the complexity of when you produce the spark or the sensing voltage. If the primary is kept energized and you turn OFF the FET you'll produce a spark (20kV). If the primary is not energized and you turn the FET ON, then you'll produce a much smaller voltage (2kV).
Put a series resistor in the primary winding to set the maximum current flow for the transformer.
Put a series diode in the high voltage transformer output so only the positive peaks reach the spark plug.
Connect your sensing resistor to the transformer output (your spark plug tip). It needs to be a high voltage resistor.
answered 5 hours ago
Jack CreaseyJack Creasey
15.5k2823
answered 5 hours ago
Jack CreaseyJack Creasey
15.5k2823
answered 5 hours ago
Jack CreaseyJack Creasey
15.5k2823
answered 5 hours ago
Jack CreaseyJack Creasey
15.5k2823
15.5k2823
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$begingroup$
1) "Could this damage my sensing circuit" - Most likely. 2) "Would this end up damaging my sensing circuit?" - Definitely. Apart from the strong EMI, you will have to provide enough insulation for the high voltage, esp. R14 and R10 must not arc/break in the presence of ~10kV. I suggest you disconnect the sensing circuit via a relay or something during the time the ingition procedure runs.
$endgroup$
– JimmyB
6 hours ago
2
$begingroup$
How do you turn your SCR off again?
$endgroup$
– Finbarr
6 hours ago
$begingroup$
If this was me I would use 2 spark plugs. This is a known method of ignition and flame detection because it is simpler that way. High energy discharges and sensitive input circuitry do not make good bedfellows.
$endgroup$
– KalleMP
3 hours ago