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High voltage LED indicator 40-1000 VDC without additional power supply

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High voltage LED indicator 40-1000 VDC without additional power supply

High Voltage Power Supply DesignBackup power supply with ledLED Strip Light - Power supply issuesPrecision High Voltage Power Supply Design?High Voltage Indicator based on specific threshold valueLED Strip setup on stairs. Unsure which power supply will work for 1200 LEDsPowering high power LEDs without resistorsPowering 3.3v-5V LED strip with 18650 batteriesHow supply or flash a LED with a low power solar cell?Power indicator for circuits with voltages much higher than LED forward voltages (say 15-48V)

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4

$begingroup$

I would like to make an indicator to show that DC bus (700VDC) capacitors are charged (be careful!).

What is the best way to make a LED indicator, which will work for a long time from 40VDC to 1000VDC without additional power supply and with minimum power losses?

led high-voltage hvdc

share|improve this question

edited 13 hours ago

Nikolay

asked 13 hours ago

NikolayNikolay

242

New contributor

Nikolay is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  "work with" how? What is the intention?
  $endgroup$
  – Eugene Sh.
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  at what? constant current?
  $endgroup$
  – Sunnyskyguy EE75
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  it should show us that DC bus capacitors are charged
  $endgroup$
  – Nikolay
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  $begingroup$
  Welcome to EE.SE! Keep in mind that questions about optimization (i.e., "What is the best ...?") require a definition about what problem dimensions are to be optimized for your application, such as size, speed, energy consumption, user experience, etc. Since these can't be optimized all at once, you need to have a good idea of which ones are most important to you, and be able to articulate that clearly to us.
  $endgroup$
  – Dave Tweed♦
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  ie. you need to supply measureable specs for the LED indicator current and perhaps you want to specify OVP too for 1kV on 700Vdc caps and max. power for this load
  $endgroup$
  – Sunnyskyguy EE75
  13 hours ago
  
  
  

  
  
  
  

 | 
show 1 more comment

4

$begingroup$

I would like to make an indicator to show that DC bus (700VDC) capacitors are charged (be careful!).

What is the best way to make a LED indicator, which will work for a long time from 40VDC to 1000VDC without additional power supply and with minimum power losses?

led high-voltage hvdc

share|improve this question

edited 13 hours ago

Nikolay

asked 13 hours ago

NikolayNikolay

242

New contributor

Nikolay is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  "work with" how? What is the intention?
  $endgroup$
  – Eugene Sh.
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  at what? constant current?
  $endgroup$
  – Sunnyskyguy EE75
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  it should show us that DC bus capacitors are charged
  $endgroup$
  – Nikolay
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  $begingroup$
  Welcome to EE.SE! Keep in mind that questions about optimization (i.e., "What is the best ...?") require a definition about what problem dimensions are to be optimized for your application, such as size, speed, energy consumption, user experience, etc. Since these can't be optimized all at once, you need to have a good idea of which ones are most important to you, and be able to articulate that clearly to us.
  $endgroup$
  – Dave Tweed♦
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  ie. you need to supply measureable specs for the LED indicator current and perhaps you want to specify OVP too for 1kV on 700Vdc caps and max. power for this load
  $endgroup$
  – Sunnyskyguy EE75
  13 hours ago
  
  
  

  
  
  
  

 | 
show 1 more comment

$begingroup$

I would like to make an indicator to show that DC bus (700VDC) capacitors are charged (be careful!).

What is the best way to make a LED indicator, which will work for a long time from 40VDC to 1000VDC without additional power supply and with minimum power losses?

led high-voltage hvdc

share|improve this question

edited 13 hours ago

Nikolay

asked 13 hours ago

NikolayNikolay

242

New contributor

Nikolay is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

$endgroup$

share|improve this question

edited 13 hours ago

Nikolay

asked 13 hours ago

NikolayNikolay

242

New contributor

Nikolay is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 13 hours ago

Nikolay

asked 13 hours ago

NikolayNikolay

242

New contributor

Nikolay 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

NikolayNikolay

242

New contributor

Nikolay 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

NikolayNikolay

242

4 Answers
4

active

oldest

votes

6

$begingroup$

Connect a moving coil analog voltmeter across the power bus.

Either a voltmeter as shown with internal series resistor or an external resistor
and scale calibrated for the desired range. Photo from this useless site.

Old-school suppliers such as Crompton should be able to supply a meter with the markings you need, if not a turnkey solution.

share|improve this answer

edited 12 hours ago

answered 13 hours ago

Spehro PefhanySpehro Pefhany

213k5162429

$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  GMTA .........great alike
  $endgroup$
  – Sunnyskyguy EE75
  13 hours ago
  

  
  
  
  

add a comment | 

4

$begingroup$

Something else to consider is to build a relaxation oscillator using a diac, capacitor, LED, couple of resistors.

Diacs are still readily available, although Digikey wants to sell them in full reels. They can be found at most electronic suppliers as well as places like eBay, aliexpress, banggood, deal extreme.

The advantage of using a relaxation oscillator rather than driving the LED with a large-value resistor is that the LED remains visible (flashing) with low voltages applied. It will stop flashing when the input voltage drops below the sum of the diac trigger voltage and the LED forward voltage,

share|improve this answer

answered 11 hours ago

Dwayne ReidDwayne Reid

18.2k21949

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Probably the best solution. Only maybe R1 should be 10 M or even more, and the cap under 1uF. Also there are LEDs with 100X light output than the listed one, so R2 can be increased too, which would save power.
  $endgroup$
  – Ale..chenski
  10 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I normally use very-high-brightness LEDs. The part number on my schematic is simply what the built-in CAD package has as a default.
  $endgroup$
  – Dwayne Reid
  10 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  You have to keep the discharge current high enough to ensure that the diac switches cleanly from conducting to not conducting. In other words, R2 has to remain fairly low value. But higher brightness is better anyway.
  $endgroup$
  – Dwayne Reid
  10 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Wouldn't using an optocoupler here be preferred to decouple and shift to lower voltage? Signal to user/operator shouldn't be powered by high-voltage if they don't have to.
  $endgroup$
  – Mast
  41 mins ago
  

  
  
  
  

add a comment | 

4

$begingroup$

example of a reliable economical no-power-supply (< $10) indicator solution that does not cost > $200 like the other meters. :(

Since this coil draws 50uA full scale it is equivalent to 10V/50uA= 200kOhm. and thus at 1kV the R load is 50 mW full scale with 1kV/50uA = 20MOhm 1% or +/-200kOhm.

^{simulate this circuit – Schematic created using CircuitLab}

It also draws the least current and is readily available.

share|improve this answer

edited 10 hours ago

answered 11 hours ago

Sunnyskyguy EE75Sunnyskyguy EE75

70.7k226103

$endgroup$

add a comment | 

3

$begingroup$

Another potential option is to use a neon bulb or lamp. The common neon indicator that I used to use is the NE-2H - this has fairly-wide current capability and would be able to handle the current range of caused by the supply voltage changing from less than 100V up to 1000V.

The downside is that a neon indicator does not match your requirement of indicating down to 40 Vdc. The NE-2H extinguishes (after being lit) at about 60 Vdc.

NE-2 & NE-2H indicators are still readily available. There are also much larger neon bulbs and lamps but they may not be readily available any longer. But you can check.

Final downside of a neon indicator is that they do die after an extended time. You have to weigh the consequences of the indicator failing some time in the future. Do note that they fail "gracefully" - they don't fail completely at one time, but rather, degrade. You would use that degradation as an indication that the lamp needs to be replaced.

share|improve this answer

answered 12 hours ago

Dwayne ReidDwayne Reid

18.2k21949

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I had considered this but discarded it due to the V range must be <<1mA with 1M series R is barely visible at 50uA , but then when it wears out you can reverse it and use the other electrode to illuminate. ha.
  $endgroup$
  – Sunnyskyguy EE75
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I had considered suggesting a simple neon relaxation oscillator but the downside is that the minimum operating voltage would be about 90 Vdc. But it doesn't get much simpler than that - and remains quite visible even with low supply voltage.
  $endgroup$
  – Dwayne Reid
  11 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Will the neon work on DC power?
  $endgroup$
  – Harper
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Yes. Neon works well on DC supply. However, only one electrode illuminates. Neon relaxation oscillator works only with DC power. But minimum operating voltage for relaxation oscillator is the firing voltage of the neon bulb - about 90 Vdc for NE-2H.
  $endgroup$
  – Dwayne Reid
  6 hours ago
  

  
  
  
  

add a comment | 

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6

$begingroup$

Connect a moving coil analog voltmeter across the power bus.

Either a voltmeter as shown with internal series resistor or an external resistor
and scale calibrated for the desired range. Photo from this useless site.

Old-school suppliers such as Crompton should be able to supply a meter with the markings you need, if not a turnkey solution.

share|improve this answer

edited 12 hours ago

answered 13 hours ago

Spehro PefhanySpehro Pefhany

213k5162429

$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  GMTA .........great alike
  $endgroup$
  – Sunnyskyguy EE75
  13 hours ago
  

  
  
  
  

add a comment | 

6

$begingroup$

Connect a moving coil analog voltmeter across the power bus.

Either a voltmeter as shown with internal series resistor or an external resistor
and scale calibrated for the desired range. Photo from this useless site.

Old-school suppliers such as Crompton should be able to supply a meter with the markings you need, if not a turnkey solution.

share|improve this answer

edited 12 hours ago

answered 13 hours ago

Spehro PefhanySpehro Pefhany

213k5162429

$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  GMTA .........great alike
  $endgroup$
  – Sunnyskyguy EE75
  13 hours ago
  

  
  
  
  

add a comment | 

$begingroup$

Connect a moving coil analog voltmeter across the power bus.

Either a voltmeter as shown with internal series resistor or an external resistor
and scale calibrated for the desired range. Photo from this useless site.

Old-school suppliers such as Crompton should be able to supply a meter with the markings you need, if not a turnkey solution.

share|improve this answer

edited 12 hours ago

answered 13 hours ago

Spehro PefhanySpehro Pefhany

213k5162429

$endgroup$

share|improve this answer

edited 12 hours ago

answered 13 hours ago

Spehro PefhanySpehro Pefhany

213k5162429

answered 13 hours ago

Spehro PefhanySpehro Pefhany

213k5162429

answered 13 hours ago

Spehro PefhanySpehro Pefhany

213k5162429

4

$begingroup$

Something else to consider is to build a relaxation oscillator using a diac, capacitor, LED, couple of resistors.

Diacs are still readily available, although Digikey wants to sell them in full reels. They can be found at most electronic suppliers as well as places like eBay, aliexpress, banggood, deal extreme.

The advantage of using a relaxation oscillator rather than driving the LED with a large-value resistor is that the LED remains visible (flashing) with low voltages applied. It will stop flashing when the input voltage drops below the sum of the diac trigger voltage and the LED forward voltage,

share|improve this answer

answered 11 hours ago

Dwayne ReidDwayne Reid

18.2k21949

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Probably the best solution. Only maybe R1 should be 10 M or even more, and the cap under 1uF. Also there are LEDs with 100X light output than the listed one, so R2 can be increased too, which would save power.
  $endgroup$
  – Ale..chenski
  10 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I normally use very-high-brightness LEDs. The part number on my schematic is simply what the built-in CAD package has as a default.
  $endgroup$
  – Dwayne Reid
  10 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  You have to keep the discharge current high enough to ensure that the diac switches cleanly from conducting to not conducting. In other words, R2 has to remain fairly low value. But higher brightness is better anyway.
  $endgroup$
  – Dwayne Reid
  10 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Wouldn't using an optocoupler here be preferred to decouple and shift to lower voltage? Signal to user/operator shouldn't be powered by high-voltage if they don't have to.
  $endgroup$
  – Mast
  41 mins ago
  

  
  
  
  

add a comment | 

4

$begingroup$

Something else to consider is to build a relaxation oscillator using a diac, capacitor, LED, couple of resistors.

Diacs are still readily available, although Digikey wants to sell them in full reels. They can be found at most electronic suppliers as well as places like eBay, aliexpress, banggood, deal extreme.

The advantage of using a relaxation oscillator rather than driving the LED with a large-value resistor is that the LED remains visible (flashing) with low voltages applied. It will stop flashing when the input voltage drops below the sum of the diac trigger voltage and the LED forward voltage,

share|improve this answer

answered 11 hours ago

Dwayne ReidDwayne Reid

18.2k21949

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Probably the best solution. Only maybe R1 should be 10 M or even more, and the cap under 1uF. Also there are LEDs with 100X light output than the listed one, so R2 can be increased too, which would save power.
  $endgroup$
  – Ale..chenski
  10 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I normally use very-high-brightness LEDs. The part number on my schematic is simply what the built-in CAD package has as a default.
  $endgroup$
  – Dwayne Reid
  10 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  You have to keep the discharge current high enough to ensure that the diac switches cleanly from conducting to not conducting. In other words, R2 has to remain fairly low value. But higher brightness is better anyway.
  $endgroup$
  – Dwayne Reid
  10 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Wouldn't using an optocoupler here be preferred to decouple and shift to lower voltage? Signal to user/operator shouldn't be powered by high-voltage if they don't have to.
  $endgroup$
  – Mast
  41 mins ago
  

  
  
  
  

add a comment | 

$begingroup$

Something else to consider is to build a relaxation oscillator using a diac, capacitor, LED, couple of resistors.

Diacs are still readily available, although Digikey wants to sell them in full reels. They can be found at most electronic suppliers as well as places like eBay, aliexpress, banggood, deal extreme.

The advantage of using a relaxation oscillator rather than driving the LED with a large-value resistor is that the LED remains visible (flashing) with low voltages applied. It will stop flashing when the input voltage drops below the sum of the diac trigger voltage and the LED forward voltage,

share|improve this answer

answered 11 hours ago

Dwayne ReidDwayne Reid

18.2k21949

$endgroup$

share|improve this answer

answered 11 hours ago

Dwayne ReidDwayne Reid

18.2k21949

answered 11 hours ago

Dwayne ReidDwayne Reid

18.2k21949

answered 11 hours ago

Dwayne ReidDwayne Reid

18.2k21949

4

$begingroup$

example of a reliable economical no-power-supply (< $10) indicator solution that does not cost > $200 like the other meters. :(

Since this coil draws 50uA full scale it is equivalent to 10V/50uA= 200kOhm. and thus at 1kV the R load is 50 mW full scale with 1kV/50uA = 20MOhm 1% or +/-200kOhm.

^{simulate this circuit – Schematic created using CircuitLab}

It also draws the least current and is readily available.

share|improve this answer

edited 10 hours ago

answered 11 hours ago

Sunnyskyguy EE75Sunnyskyguy EE75

70.7k226103

$endgroup$

add a comment | 

4

$begingroup$

example of a reliable economical no-power-supply (< $10) indicator solution that does not cost > $200 like the other meters. :(

Since this coil draws 50uA full scale it is equivalent to 10V/50uA= 200kOhm. and thus at 1kV the R load is 50 mW full scale with 1kV/50uA = 20MOhm 1% or +/-200kOhm.

^{simulate this circuit – Schematic created using CircuitLab}

It also draws the least current and is readily available.

share|improve this answer

edited 10 hours ago

answered 11 hours ago

Sunnyskyguy EE75Sunnyskyguy EE75

70.7k226103

$endgroup$

add a comment | 

$begingroup$

example of a reliable economical no-power-supply (< $10) indicator solution that does not cost > $200 like the other meters. :(

Since this coil draws 50uA full scale it is equivalent to 10V/50uA= 200kOhm. and thus at 1kV the R load is 50 mW full scale with 1kV/50uA = 20MOhm 1% or +/-200kOhm.

^{simulate this circuit – Schematic created using CircuitLab}

It also draws the least current and is readily available.

share|improve this answer

edited 10 hours ago

answered 11 hours ago

Sunnyskyguy EE75Sunnyskyguy EE75

70.7k226103

$endgroup$

share|improve this answer

edited 10 hours ago

answered 11 hours ago

Sunnyskyguy EE75Sunnyskyguy EE75

70.7k226103

answered 11 hours ago

Sunnyskyguy EE75Sunnyskyguy EE75

70.7k226103

answered 11 hours ago

Sunnyskyguy EE75Sunnyskyguy EE75

70.7k226103

3

$begingroup$

Another potential option is to use a neon bulb or lamp. The common neon indicator that I used to use is the NE-2H - this has fairly-wide current capability and would be able to handle the current range of caused by the supply voltage changing from less than 100V up to 1000V.

The downside is that a neon indicator does not match your requirement of indicating down to 40 Vdc. The NE-2H extinguishes (after being lit) at about 60 Vdc.

NE-2 & NE-2H indicators are still readily available. There are also much larger neon bulbs and lamps but they may not be readily available any longer. But you can check.

Final downside of a neon indicator is that they do die after an extended time. You have to weigh the consequences of the indicator failing some time in the future. Do note that they fail "gracefully" - they don't fail completely at one time, but rather, degrade. You would use that degradation as an indication that the lamp needs to be replaced.

share|improve this answer

answered 12 hours ago

Dwayne ReidDwayne Reid

18.2k21949

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I had considered this but discarded it due to the V range must be <<1mA with 1M series R is barely visible at 50uA , but then when it wears out you can reverse it and use the other electrode to illuminate. ha.
  $endgroup$
  – Sunnyskyguy EE75
  12 hours ago
  

  
  
  
  


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  I had considered suggesting a simple neon relaxation oscillator but the downside is that the minimum operating voltage would be about 90 Vdc. But it doesn't get much simpler than that - and remains quite visible even with low supply voltage.
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  – Dwayne Reid
  11 hours ago
  

  
  
  
  


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  Will the neon work on DC power?
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  – Harper
  6 hours ago
  

  
  
  
  


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  Yes. Neon works well on DC supply. However, only one electrode illuminates. Neon relaxation oscillator works only with DC power. But minimum operating voltage for relaxation oscillator is the firing voltage of the neon bulb - about 90 Vdc for NE-2H.
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  – Dwayne Reid
  6 hours ago
  

  
  
  
  

add a comment | 

3

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Another potential option is to use a neon bulb or lamp. The common neon indicator that I used to use is the NE-2H - this has fairly-wide current capability and would be able to handle the current range of caused by the supply voltage changing from less than 100V up to 1000V.

The downside is that a neon indicator does not match your requirement of indicating down to 40 Vdc. The NE-2H extinguishes (after being lit) at about 60 Vdc.

NE-2 & NE-2H indicators are still readily available. There are also much larger neon bulbs and lamps but they may not be readily available any longer. But you can check.

Final downside of a neon indicator is that they do die after an extended time. You have to weigh the consequences of the indicator failing some time in the future. Do note that they fail "gracefully" - they don't fail completely at one time, but rather, degrade. You would use that degradation as an indication that the lamp needs to be replaced.

share|improve this answer

answered 12 hours ago

Dwayne ReidDwayne Reid

18.2k21949

$endgroup$

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  I had considered this but discarded it due to the V range must be <<1mA with 1M series R is barely visible at 50uA , but then when it wears out you can reverse it and use the other electrode to illuminate. ha.
  $endgroup$
  – Sunnyskyguy EE75
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I had considered suggesting a simple neon relaxation oscillator but the downside is that the minimum operating voltage would be about 90 Vdc. But it doesn't get much simpler than that - and remains quite visible even with low supply voltage.
  $endgroup$
  – Dwayne Reid
  11 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Will the neon work on DC power?
  $endgroup$
  – Harper
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Yes. Neon works well on DC supply. However, only one electrode illuminates. Neon relaxation oscillator works only with DC power. But minimum operating voltage for relaxation oscillator is the firing voltage of the neon bulb - about 90 Vdc for NE-2H.
  $endgroup$
  – Dwayne Reid
  6 hours ago
  

  
  
  
  

add a comment | 

$begingroup$

Another potential option is to use a neon bulb or lamp. The common neon indicator that I used to use is the NE-2H - this has fairly-wide current capability and would be able to handle the current range of caused by the supply voltage changing from less than 100V up to 1000V.

The downside is that a neon indicator does not match your requirement of indicating down to 40 Vdc. The NE-2H extinguishes (after being lit) at about 60 Vdc.

NE-2 & NE-2H indicators are still readily available. There are also much larger neon bulbs and lamps but they may not be readily available any longer. But you can check.

Final downside of a neon indicator is that they do die after an extended time. You have to weigh the consequences of the indicator failing some time in the future. Do note that they fail "gracefully" - they don't fail completely at one time, but rather, degrade. You would use that degradation as an indication that the lamp needs to be replaced.

share|improve this answer

answered 12 hours ago

Dwayne ReidDwayne Reid

18.2k21949

$endgroup$

share|improve this answer

answered 12 hours ago

Dwayne ReidDwayne Reid

18.2k21949

answered 12 hours ago

Dwayne ReidDwayne Reid

18.2k21949

answered 12 hours ago

Dwayne ReidDwayne Reid

18.2k21949