How much current to kill an insect?...

[Commander Kinsey]

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

 

[Mike Coon]

In article <op.1lqyzpe3mvhs6z@ryzen.lan>, CK1@nospam.com says...

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death
requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

Is your electrostatic voltmeter leaky? It should only \"draw\" a charge,
not a current.

BTW I don\'t want my wasps fried, because then the spider to which I
offer them is not interested. They have to wake up and flutter, then she
swoops and bites...

 

[Commander Kinsey]

On Fri, 06 May 2022 16:31:25 +0100, Mike Coon <gravity@mjcoon.plus.com> wrote:

In article <op.1lqyzpe3mvhs6z@ryzen.lan>, CK1@nospam.com says...

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death
requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

Is your electrostatic voltmeter leaky? It should only \"draw\" a charge,
not a current.

I\'m not familiar with electrostatic voltmeters. I bought it as an antique and was surprised it works. A normal voltmeter draws current does it not?

BTW I don\'t want my wasps fried, because then the spider to which I
offer them is not interested. They have to wake up and flutter, then she
swoops and bites...

It\'s amusing when the spider goes to get them and gets zapped too.

Anyway I\'m going to go with power, 5W. That\'s enough heat to fry an insect.

 

[server]

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
<CK1@nospam.com> wrote:

>I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.



--

Anybody can count to one.

- Robert Widlar

 

[Commander Kinsey]

On Fri, 06 May 2022 17:06:28 +0100, <jlarkin@highlandsniptechnology.com> wrote:

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
CK1@nospam.com> wrote:

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.

Since when I unplug the USB cord, the voltage drops to 0 instantly, I doubt there\'s a cap in it.

The mains one is just a 240V to 2000V transformer directly connected to the rails.

 

[John Larkin]

On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
<CK1@nospam.com> wrote:

On Fri, 06 May 2022 17:06:28 +0100, <jlarkin@highlandsniptechnology.com> wrote:

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
CK1@nospam.com> wrote:

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.

Since when I unplug the USB cord, the voltage drops to 0 instantly, I doubt there\'s a cap in it.

It wouldn\'t be hard to measure. Or google.

The mains one is just a 240V to 2000V transformer directly connected to the rails.

That sounds lethal to bugs and to humans. And a fire hazard.

One outfit that I work with considers 9 joules the be the human
threshold of death. I\'d guess that 1 joule would take out a mosquito.




--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[John Walliker]

On Friday, 6 May 2022 at 19:44:05 UTC+1, John Larkin wrote:

On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

On Fri, 06 May 2022 17:06:28 +0100, <jla...@highlandsniptechnology.com> wrote:

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.

Since when I unplug the USB cord, the voltage drops to 0 instantly, I doubt there\'s a cap in it.
It wouldn\'t be hard to measure. Or google.

The mains one is just a 240V to 2000V transformer directly connected to the rails.
That sounds lethal to bugs and to humans. And a fire hazard.

One outfit that I work with considers 9 joules the be the human
threshold of death. I\'d guess that 1 joule would take out a mosquito.

These devices used to make a loud noise as they discharged a capacitor
into the insect. This is no longer considered a good idea because if the
insect explodes too violently the bacteria-laden fragments are dispersed
over a wide area. It is much better just to cook them without fragmentation.
I did once come across a standard for such devices - I will see if I can find it.
John

 

[whit3rd]

On Friday, May 6, 2022 at 11:44:05 AM UTC-7, John Larkin wrote:

On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

[about a bug zapper]

The mains one is just a 240V to 2000V transformer directly connected to the rails.

That sounds lethal to bugs and to humans. And a fire hazard.

The \'transformer\' may be a potted circuit, with current limits like
in a neon transformer. It won\'t be tightly line-coupled like an ideal
power transformer.

One outfit that I work with considers 9 joules the be the human
threshold of death. I\'d guess that 1 joule would take out a mosquito.

The human threshold has to do with heart-stoppage; the insect lethality
is more about heating ( boiling temperature rather than fever).
You can\'t bollix the circulatory system of an insect, because it\'s
mainly just diffusion.

 

[Phil Hobbs]

John Walliker wrote:

On Friday, 6 May 2022 at 19:44:05 UTC+1, John Larkin wrote:
On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

On Fri, 06 May 2022 17:06:28 +0100, <jla...@highlandsniptechnology.com> wrote:

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.

Since when I unplug the USB cord, the voltage drops to 0 instantly, I doubt there\'s a cap in it.
It wouldn\'t be hard to measure. Or google.

The mains one is just a 240V to 2000V transformer directly connected to the rails.
That sounds lethal to bugs and to humans. And a fire hazard.

One outfit that I work with considers 9 joules the be the human
threshold of death. I\'d guess that 1 joule would take out a mosquito.

These devices used to make a loud noise as they discharged a capacitor
into the insect. This is no longer considered a good idea because if the
insect explodes too violently the bacteria-laden fragments are dispersed
over a wide area. It is much better just to cook them without fragmentation.
I did once come across a standard for such devices - I will see if I can find it.
John

Bacteria-laden fragments over a wide area? From a mosquito whose total
mass is a few milligrams?

Sure must be peaceful where you live, if that\'s the biggest worry.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Mike Coon]

In article <op.1lq7pcwlmvhs6z@ryzen.lan>, CK1@nospam.com says...

On Fri, 06 May 2022 16:31:25 +0100, Mike Coon <gravity@mjcoon.plus.com> wrote:

In article <op.1lqyzpe3mvhs6z@ryzen.lan>, CK1@nospam.com says...

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death
requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

Is your electrostatic voltmeter leaky? It should only \"draw\" a charge,
not a current.

I\'m not familiar with electrostatic voltmeters. I bought it as an antique and was surprised it works. A normal voltmeter draws current does it not?

From what I remember of the one we had in our physics department at
college they measure the electrostatic attraction between a pair (or
multiple pairs) of plates connected to the input. So the whole thing is
a capacitor of variable value, because the plates move in relation to
each other. Thus the only current flow should be that needed to charge
up that capacitor. (Unless there is leakage.)

 

[John Larkin]

On Fri, 6 May 2022 12:02:11 -0700 (PDT), John Walliker
<jrwalliker@gmail.com> wrote:

On Friday, 6 May 2022 at 19:44:05 UTC+1, John Larkin wrote:
On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

On Fri, 06 May 2022 17:06:28 +0100, <jla...@highlandsniptechnology.com> wrote:

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.

Since when I unplug the USB cord, the voltage drops to 0 instantly, I doubt there\'s a cap in it.
It wouldn\'t be hard to measure. Or google.

The mains one is just a 240V to 2000V transformer directly connected to the rails.
That sounds lethal to bugs and to humans. And a fire hazard.

One outfit that I work with considers 9 joules the be the human
threshold of death. I\'d guess that 1 joule would take out a mosquito.

These devices used to make a loud noise as they discharged a capacitor
into the insect. This is no longer considered a good idea because if the
insect explodes too violently the bacteria-laden fragments are dispersed
over a wide area. It is much better just to cook them without fragmentation.
I did once come across a standard for such devices - I will see if I can find it.
John

I\'d rather a mosquito go POP 10 feet away, than it being smooshed
against my arm after it bit me.

The bug zapper schematics that I can google are mostly a tiny blocking
oscillator driving a step-up flyback into a capacitor. Must be
milliwatts into the cap.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[Commander Kinsey]

On Fri, 06 May 2022 19:43:52 +0100, John Larkin <jlarkin@highland_atwork_technology.com> wrote:

On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
CK1@nospam.com> wrote:

On Fri, 06 May 2022 17:06:28 +0100, <jlarkin@highlandsniptechnology.com> wrote:

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
CK1@nospam.com> wrote:

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.

Since when I unplug the USB cord, the voltage drops to 0 instantly, I doubt there\'s a cap in it.

It wouldn\'t be hard to measure. Or google.

I used a screwdriver. It\'s a cap, and a tiny transformer with a transistor and some passives. I guess it discharges through the safety resistors very quickly, which means there won\'t be much jolt in it for the insect.

The mains one is just a 240V to 2000V transformer directly connected to the rails.

That sounds lethal to bugs and to humans. And a fire hazard.

It\'s a proper insectocutor (the biggest well known make). How can it be a fire hazard when it\'s contained?

It\'s great fun to watch a wasp getting fried. It fucking stinks though.

One outfit that I work with considers 9 joules the be the human
threshold of death. I\'d guess that 1 joule would take out a mosquito.

 

[Commander Kinsey]

On Fri, 06 May 2022 20:02:11 +0100, John Walliker <jrwalliker@gmail.com> wrote:

On Friday, 6 May 2022 at 19:44:05 UTC+1, John Larkin wrote:
On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

On Fri, 06 May 2022 17:06:28 +0100, <jla...@highlandsniptechnology.com> wrote:

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.

Since when I unplug the USB cord, the voltage drops to 0 instantly, I doubt there\'s a cap in it.
It wouldn\'t be hard to measure. Or google.

The mains one is just a 240V to 2000V transformer directly connected to the rails.
That sounds lethal to bugs and to humans. And a fire hazard.

One outfit that I work with considers 9 joules the be the human
threshold of death. I\'d guess that 1 joule would take out a mosquito.

These devices used to make a loud noise as they discharged a capacitor
into the insect. This is no longer considered a good idea because if the
insect explodes too violently the bacteria-laden fragments are dispersed
over a wide area. It is much better just to cook them without fragmentation.
I did once come across a standard for such devices - I will see if I can find it.
John

That would be why the decent one I have fries them gently, while the cheap Chinese USB one uses a capacitor.

 

[Commander Kinsey]

On Fri, 06 May 2022 21:43:06 +0100, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

John Walliker wrote:
On Friday, 6 May 2022 at 19:44:05 UTC+1, John Larkin wrote:
On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

On Fri, 06 May 2022 17:06:28 +0100, <jla...@highlandsniptechnology.com> wrote:

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.

Since when I unplug the USB cord, the voltage drops to 0 instantly, I doubt there\'s a cap in it.
It wouldn\'t be hard to measure. Or google.

The mains one is just a 240V to 2000V transformer directly connected to the rails.
That sounds lethal to bugs and to humans. And a fire hazard.

One outfit that I work with considers 9 joules the be the human
threshold of death. I\'d guess that 1 joule would take out a mosquito.

These devices used to make a loud noise as they discharged a capacitor
into the insect. This is no longer considered a good idea because if the
insect explodes too violently the bacteria-laden fragments are dispersed
over a wide area. It is much better just to cook them without fragmentation.
I did once come across a standard for such devices - I will see if I can find it.
John


Bacteria-laden fragments over a wide area? From a mosquito whose total
mass is a few milligrams?

Sure must be peaceful where you live, if that\'s the biggest worry.

The insect when not killed is presumably spreading that bacteria on food anyway.

 

[Commander Kinsey]

On Fri, 06 May 2022 21:59:43 +0100, Mike Coon <gravity@mjcoon.plus.com> wrote:

In article <op.1lq7pcwlmvhs6z@ryzen.lan>, CK1@nospam.com says...

On Fri, 06 May 2022 16:31:25 +0100, Mike Coon <gravity@mjcoon.plus.com> wrote:

In article <op.1lqyzpe3mvhs6z@ryzen.lan>, CK1@nospam.com says...

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death
requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

Is your electrostatic voltmeter leaky? It should only \"draw\" a charge,
not a current.

I\'m not familiar with electrostatic voltmeters. I bought it as an antique and was surprised it works. A normal voltmeter draws current does it not?

From what I remember of the one we had in our physics department at
college they measure the electrostatic attraction between a pair (or
multiple pairs) of plates connected to the input. So the whole thing is
a capacitor of variable value, because the plates move in relation to
each other. Thus the only current flow should be that needed to charge
up that capacitor. (Unless there is leakage.)

Why are they no longer made like that? Digital ones use a fair amount of current which is annoying in some circuits.

 

[John Larkin]

On Fri, 6 May 2022 12:16:10 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Friday, May 6, 2022 at 11:44:05 AM UTC-7, John Larkin wrote:
On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

[about a bug zapper]

The mains one is just a 240V to 2000V transformer directly connected to the rails.

That sounds lethal to bugs and to humans. And a fire hazard.

The \'transformer\' may be a potted circuit, with current limits like
in a neon transformer. It won\'t be tightly line-coupled like an ideal
power transformer.

Any 60 Hz transformer that makes kilovolts is going to be huge. Loose
coupling and potting make them huger.

The old neon sign transformers were huge; the modern one are high
frequency oscillators. The old ones looked nicer for some reason.

When I was a kid I had an infinite supply of used neon sign
transformers. Fun. The double-ended 18 KV was my favorite, but it must
have weighed 20 pounds.

The old oil-filled car ignition transformers were cool too, driven
from an oil cap through a thyratron. 3\" sparks.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[Commander Kinsey]

On Fri, 06 May 2022 22:59:27 +0100, John Larkin <jlarkin@highland_atwork_technology.com> wrote:

On Fri, 6 May 2022 12:02:11 -0700 (PDT), John Walliker
jrwalliker@gmail.com> wrote:

On Friday, 6 May 2022 at 19:44:05 UTC+1, John Larkin wrote:
On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

On Fri, 06 May 2022 17:06:28 +0100, <jla...@highlandsniptechnology.com> wrote:

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.

Since when I unplug the USB cord, the voltage drops to 0 instantly, I doubt there\'s a cap in it.
It wouldn\'t be hard to measure. Or google.

The mains one is just a 240V to 2000V transformer directly connected to the rails.
That sounds lethal to bugs and to humans. And a fire hazard.

One outfit that I work with considers 9 joules the be the human
threshold of death. I\'d guess that 1 joule would take out a mosquito.

These devices used to make a loud noise as they discharged a capacitor
into the insect. This is no longer considered a good idea because if the
insect explodes too violently the bacteria-laden fragments are dispersed
over a wide area. It is much better just to cook them without fragmentation.
I did once come across a standard for such devices - I will see if I can find it.
John

I\'d rather a mosquito go POP 10 feet away, than it being smooshed
against my arm after it bit me.

The bug zapper schematics that I can google are mostly a tiny blocking
oscillator driving a step-up flyback into a capacitor. Must be
milliwatts into the cap.

Mine gets warm. I\'m guessing it uses a lot of the 5W rating all the time. I can send a photo of the circuit if you want.

 

[Commander Kinsey]

On Fri, 06 May 2022 23:07:32 +0100, John Larkin <jlarkin@highland_atwork_technology.com> wrote:

On Fri, 6 May 2022 12:16:10 -0700 (PDT), whit3rd <whit3rd@gmail.com
wrote:

On Friday, May 6, 2022 at 11:44:05 AM UTC-7, John Larkin wrote:
On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

[about a bug zapper]

The mains one is just a 240V to 2000V transformer directly connected to the rails.

That sounds lethal to bugs and to humans. And a fire hazard.

The \'transformer\' may be a potted circuit, with current limits like
in a neon transformer. It won\'t be tightly line-coupled like an ideal
power transformer.

Any 60 Hz

50, I live in the modern world.

transformer that makes kilovolts is going to be huge. Loose
coupling and potting make them huger.

Only huge if high power. Mine is about 1.5 inches x 1.5 inches x 1.5 inches.

The old neon sign transformers were huge; the modern one are high
frequency oscillators. The old ones looked nicer for some reason.

The light output or the circuit looked nicer?

When I was a kid I had an infinite supply of used neon sign
transformers. Fun. The double-ended 18 KV was my favorite, but it must
have weighed 20 pounds.

How many friends did you torture with it?

The old oil-filled car ignition transformers were cool too, driven
from an oil cap through a thyratron. 3\" sparks.

Could you kill someone with those? I\'ve been told that contrary to popular belief, the \"modern\" ones from the 90s (pre electronic ignition) didn\'t have enough current to kill you. I heard of one mechanic grabbing one, he couldn\'t let go but he was unharmed.

 

[Lasse Langwadt Christensen]

lørdag den 7. maj 2022 kl. 00.54.24 UTC+2 skrev Commander Kinsey:

On Fri, 06 May 2022 23:07:32 +0100, John Larkin <jlarkin@highland_atwork_technology.com> wrote:

On Fri, 6 May 2022 12:16:10 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:

On Friday, May 6, 2022 at 11:44:05 AM UTC-7, John Larkin wrote:
On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

[about a bug zapper]

The mains one is just a 240V to 2000V transformer directly connected to the rails.

That sounds lethal to bugs and to humans. And a fire hazard.

The \'transformer\' may be a potted circuit, with current limits like
in a neon transformer. It won\'t be tightly line-coupled like an ideal
power transformer.

Any 60 Hz
50, I live in the modern world.
transformer that makes kilovolts is going to be huge. Loose
coupling and potting make them huger.
Only huge if high power. Mine is about 1.5 inches x 1.5 inches x 1.5 inches.
The old neon sign transformers were huge; the modern one are high
frequency oscillators. The old ones looked nicer for some reason.
The light output or the circuit looked nicer?
When I was a kid I had an infinite supply of used neon sign
transformers. Fun. The double-ended 18 KV was my favorite, but it must
have weighed 20 pounds.
How many friends did you torture with it?
The old oil-filled car ignition transformers were cool too, driven
from an oil cap through a thyratron. 3\" sparks.
Could you kill someone with those? I\'ve been told that contrary to popular belief, the \"modern\" ones from the 90s (pre electronic ignition) didn\'t have enough current to kill you. I heard of one mechanic grabbing one, he couldn\'t let go but he was unharmed.

and ignition coil is a few 100 mJ, a defibrillator is 1000x that

 

[John Larkin]

On Fri, 6 May 2022 16:43:06 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

John Walliker wrote:
On Friday, 6 May 2022 at 19:44:05 UTC+1, John Larkin wrote:
On Fri, 06 May 2022 17:40:45 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

On Fri, 06 May 2022 17:06:28 +0100, <jla...@highlandsniptechnology.com> wrote:

On Fri, 06 May 2022 13:44:03 +0100, \"Commander Kinsey\"
C...@nospam.com> wrote:

I\'m talking about the bug zappers. I have a mains one which makes 2000V. I have a USB one which makes 1700V. I can and have measured those. The mains one is very effective, I see it frying wasps. I haven\'t had the opportunity to see the USB one in action yet and I\'m wondering if it will do anything useful. How much current is required to kill the insect? I know 80mA+ is needed to kill a human through the heart, but I get the feeling with insects the death requires evaporation, not just stopping the heart. I could connect a milliammeter across the USB one\'s output, but I don\'t want to break the meter if there\'s a strong pulse to start with. The USB one states 1A 5V input, so the output couldn\'t continuously exceed only 3mA, unless it drops to 100V and gives out 50mA, and the output drops from 1700V to 0V immediately I turn it off (with an antique electrostatic voltmeter connected which may draw a bit).

It\'s energy, from a capacitor, not current that kills bugs.

The cap charging current is likely microamps.

Since when I unplug the USB cord, the voltage drops to 0 instantly, I doubt there\'s a cap in it.
It wouldn\'t be hard to measure. Or google.

The mains one is just a 240V to 2000V transformer directly connected to the rails.
That sounds lethal to bugs and to humans. And a fire hazard.

One outfit that I work with considers 9 joules the be the human
threshold of death. I\'d guess that 1 joule would take out a mosquito.

These devices used to make a loud noise as they discharged a capacitor
into the insect. This is no longer considered a good idea because if the
insect explodes too violently the bacteria-laden fragments are dispersed
over a wide area. It is much better just to cook them without fragmentation.
I did once come across a standard for such devices - I will see if I can find it.
John


Bacteria-laden fragments over a wide area? From a mosquito whose total
mass is a few milligrams?

Sure must be peaceful where you live, if that\'s the biggest worry.

Cheers

Phil Hobbs

Speak for yourself. Where I grew up, the mosquitoes were as big as
chickens.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon