Question About Safety Of Voltage Supply

D

Dave.H

Guest
I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks

Dave
 
"Dave.H" <the1930s@googlemail.com> wrote in message
news:bc083361-8e07-4b96-a1c7-940cb8bc97c3@d4g2000prg.googlegroups.com...
I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks

Dave
Click to expand...

You might be able to feel it. However, batteries will probably support even
more current than a wall transformer. So, just pay attention when you are
playing with it.

Regards,
Bob Monsen
 
On Mar 19, 3:43 pm, "Bob Monsen" <rcmon...@gmail.com> wrote:
"Dave.H" <the19...@googlemail.com> wrote in message

news:bc083361-8e07-4b96-a1c7-940cb8bc97c3@d4g2000prg.googlegroups.com...

I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks

Dave

You might be able to feel it. However, batteries will probably support even
more current than a wall transformer. So, just pay attention when you are
playing with it.

Regards,
Bob Monsen
Click to expand...
I don't mind if it hurts, just as long as it's not lethal, the radio
is only using one tube, I've been told it doesn't use much current.
I'll still be supplying the filament voltage via batteries.
 
"Dave.H" <the1930s@googlemail.com> wrote in message
news:bc083361-8e07-4b96-a1c7-940cb8bc97c3@d4g2000prg.googlegroups.com...
I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks
Click to expand...
In general that amount of voltage will not do anything. Even 120 is usually
not lethal in most circumstances(I don't mean that you go around playing
with it but I mean in most accidents when people get shocked).

At around 50V or more is when there is enough voltage to start to break
through the skin. Your skin is essentially like a resistive coating. It has
a high resistance but is thin. If the skin is wet or broken(With fluids)
then its worse Dry skin has about 500kOhm resistance so its no big deal. (at
100V thats only 0.2mA which is not enough to kill)

Wet skin is like 1kOhm so its 500 times more likely to get shocked if your
wet. This means its about 100mA(@100V) and enough to kill if it goes through
your heart.

Note though that the current does not flow ont he surface of your skin but
goes into your fluids where there are electrolytes and its much less
resistive(essentially your veins are like copper wires and your skin like a
resistor).

This is why the 9V shocks your tonge. Its probably sending an aweful lot of
current(probably 50mA is my guess on average) but does nothing because its
only on your tonge. (although I imagine a 9V can kill if placed "across the
heart".


The real issue is not shock. Its getting shocked in such a way that current
passes through your heart. (although serious burns can occur otherwise but
its usually rare)

The trick in working with "high voltage" is never to use two hands. The
reason why most people who die from electric shock is because they use two
hands and current will flow from one hand, through the blood into the heart
then out the other hand. Use one hand and probably at most you'll get
shocked. You can also wear some gloves if your still afraid. (even with one
hand its possible the current will go through your heart but much less
likely. If the other parts of your body are not being grounded in any way
then it's usually ok)

Main's is much worse because ground is earth ground. If you are working on a
power supply then you usually use a transformer and the only way to get
shocked is for your body to make a circuit with the ground on the secondary
side. This is pretty much impossible(except on your hand) if you keep one
hand away. (although there are allways accidents)

I think as long as you are careful then it will be ok. Its about 30kV/cm for
voltage to be able to "get you" through air. This means at 100V its only
like 33um. (about the size of a human hair)

The main thing is to just think about what your doing and don't be clumsy.
If you pay attention to what your doing and know the dangers and what is
dangerous in what your trying to measure then usually you'll be ok. Then, in
the rare chance that you get shocked usually it's not fatal. Its basically
like driving a car.
 
On Mar 19, 5:36 pm, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com> wrote:
"Dave.H" <the19...@googlemail.com> wrote in message

news:bc083361-8e07-4b96-a1c7-940cb8bc97c3@d4g2000prg.googlegroups.com...

I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks

In general that amount of voltage will not do anything. Even 120 is usually
not lethal in most circumstances(I don't mean that you go around playing
with it but I mean in most accidents when people get shocked).

At around 50V or more is when there is enough voltage to start to break
through the skin. Your skin is essentially like a resistive coating. It has
a high resistance but is thin. If the skin is wet or broken(With fluids)
then its worse Dry skin has about 500kOhm resistance so its no big deal. (at
100V thats only 0.2mA which is not enough to kill)

Wet skin is like 1kOhm so its 500 times more likely to get shocked if your
wet. This means its about 100mA(@100V) and enough to kill if it goes through
your heart.

Note though that the current does not flow ont he surface of your skin but
goes into your fluids where there are electrolytes and its much less
resistive(essentially your veins are like copper wires and your skin like a
resistor).

This is why the 9V shocks your tonge. Its probably sending an aweful lot of
current(probably 50mA is my guess on average) but does nothing because its
only on your tonge. (although I imagine a 9V can kill if placed "across the
heart".

The real issue is not shock. Its getting shocked in such a way that current
passes through your heart. (although serious burns can occur otherwise but
its usually rare)

The trick in working with "high voltage" is never to use two hands. The
reason why most people who die from electric shock is because they use two
hands and current will flow from one hand, through the blood into the heart
then out the other hand. Use one hand and probably at most you'll get
shocked. You can also wear some gloves if your still afraid. (even with one
hand its possible the current will go through your heart but much less
likely. If the other parts of your body are not being grounded in any way
then it's usually ok)

Main's is much worse because ground is earth ground. If you are working on a
power supply then you usually use a transformer and the only way to get
shocked is for your body to make a circuit with the ground on the secondary
side. This is pretty much impossible(except on your hand) if you keep one
hand away. (although there are allways accidents)

I think as long as you are careful then it will be ok. Its about 30kV/cm for
voltage to be able to "get you" through air. This means at 100V its only
like 33um. (about the size of a human hair)

The main thing is to just think about what your doing and don't be clumsy.
If you pay attention to what your doing and know the dangers and what is
dangerous in what your trying to measure then usually you'll be ok. Then, in
the rare chance that you get shocked usually it's not fatal. Its basically
like driving a car.
Click to expand...
I knew about the one hand in pocket technique. The radio has exposed
fahnestock clips for the power, so I'll have to be really careful,
applying power only when my hands are clear, and keeping the cats out
of the room when operating the set. Would the set have hum powered
from these switch mode power supplys? I have a 2200 MFD 50 volt cap I
can use for a filter cap if needed.
 
On 3ÔÂ19ČŐ, ĎÂÎç12Ęą14ˇÖ, "Dave.H" <the19...@googlemail.com> wrote:
I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks

Dave
Click to expand...


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"Dave.H" <the1930s@googlemail.com> wrote in message
news:39f000d7-096f-44c0-8096-e62d43ab5fb5@m34g2000hsc.googlegroups.com...
On Mar 19, 5:36 pm, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com> wrote:
"Dave.H" <the19...@googlemail.com> wrote in message

news:bc083361-8e07-4b96-a1c7-940cb8bc97c3@d4g2000prg.googlegroups.com...

I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks

In general that amount of voltage will not do anything. Even 120 is
usually
not lethal in most circumstances(I don't mean that you go around playing
with it but I mean in most accidents when people get shocked).

At around 50V or more is when there is enough voltage to start to break
through the skin. Your skin is essentially like a resistive coating. It
has
a high resistance but is thin. If the skin is wet or broken(With fluids)
then its worse Dry skin has about 500kOhm resistance so its no big deal.
(at
100V thats only 0.2mA which is not enough to kill)

Wet skin is like 1kOhm so its 500 times more likely to get shocked if
your
wet. This means its about 100mA(@100V) and enough to kill if it goes
through
your heart.

Note though that the current does not flow ont he surface of your skin
but
goes into your fluids where there are electrolytes and its much less
resistive(essentially your veins are like copper wires and your skin like
a
resistor).

This is why the 9V shocks your tonge. Its probably sending an aweful lot
of
current(probably 50mA is my guess on average) but does nothing because
its
only on your tonge. (although I imagine a 9V can kill if placed "across
the
heart".

The real issue is not shock. Its getting shocked in such a way that
current
passes through your heart. (although serious burns can occur otherwise
but
its usually rare)

The trick in working with "high voltage" is never to use two hands. The
reason why most people who die from electric shock is because they use
two
hands and current will flow from one hand, through the blood into the
heart
then out the other hand. Use one hand and probably at most you'll get
shocked. You can also wear some gloves if your still afraid. (even with
one
hand its possible the current will go through your heart but much less
likely. If the other parts of your body are not being grounded in any way
then it's usually ok)

Main's is much worse because ground is earth ground. If you are working
on a
power supply then you usually use a transformer and the only way to get
shocked is for your body to make a circuit with the ground on the
secondary
side. This is pretty much impossible(except on your hand) if you keep one
hand away. (although there are allways accidents)

I think as long as you are careful then it will be ok. Its about 30kV/cm
for
voltage to be able to "get you" through air. This means at 100V its only
like 33um. (about the size of a human hair)

The main thing is to just think about what your doing and don't be
clumsy.
If you pay attention to what your doing and know the dangers and what is
dangerous in what your trying to measure then usually you'll be ok. Then,
in
the rare chance that you get shocked usually it's not fatal. Its
basically
like driving a car.

I knew about the one hand in pocket technique. The radio has exposed
fahnestock clips for the power, so I'll have to be really careful,
applying power only when my hands are clear, and keeping the cats out
of the room when operating the set. Would the set have hum powered
from these switch mode power supplys? I have a 2200 MFD 50 volt cap I
can use for a filter cap if needed.
Click to expand...
Might be best to stay in aus.electronics Dave :)
--
Cheers ............. Rheilly
 
On Mar 19, 2:50 am, "Dave.H" <the19...@googlemail.com> wrote:
On Mar 19, 5:36 pm, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com> wrote:



"Dave.H" <the19...@googlemail.com> wrote in message

news:bc083361-8e07-4b96-a1c7-940cb8bc97c3@d4g2000prg.googlegroups.com...

I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks

In general that amount of voltage will not do anything. Even 120 is usually
not lethal in most circumstances(I don't mean that you go around playing
with it but I mean in most accidents when people get shocked).

At around 50V or more is when there is enough voltage to start to break
through the skin. Your skin is essentially like a resistive coating. It has
a high resistance but is thin. If the skin is wet or broken(With fluids)
then its worse Dry skin has about 500kOhm resistance so its no big deal. (at
100V thats only 0.2mA which is not enough to kill)

Wet skin is like 1kOhm so its 500 times more likely to get shocked if your
wet. This means its about 100mA(@100V) and enough to kill if it goes through
your heart.

Note though that the current does not flow ont he surface of your skin but
goes into your fluids where there are electrolytes and its much less
resistive(essentially your veins are like copper wires and your skin like a
resistor).

This is why the 9V shocks your tonge. Its probably sending an aweful lot of
current(probably 50mA is my guess on average) but does nothing because its
only on your tonge. (although I imagine a 9V can kill if placed "across the
heart".

The real issue is not shock. Its getting shocked in such a way that current
passes through your heart. (although serious burns can occur otherwise but
its usually rare)

The trick in working with "high voltage" is never to use two hands. The
reason why most people who die from electric shock is because they use two
hands and current will flow from one hand, through the blood into the heart
then out the other hand. Use one hand and probably at most you'll get
shocked. You can also wear some gloves if your still afraid. (even with one
hand its possible the current will go through your heart but much less
likely. If the other parts of your body are not being grounded in any way
then it's usually ok)

Main's is much worse because ground is earth ground. If you are working on a
power supply then you usually use a transformer and the only way to get
shocked is for your body to make a circuit with the ground on the secondary
side. This is pretty much impossible(except on your hand) if you keep one
hand away. (although there are allways accidents)

I think as long as you are careful then it will be ok. Its about 30kV/cm for
voltage to be able to "get you" through air. This means at 100V its only
like 33um. (about the size of a human hair)

The main thing is to just think about what your doing and don't be clumsy.
If you pay attention to what your doing and know the dangers and what is
dangerous in what your trying to measure then usually you'll be ok. Then, in
the rare chance that you get shocked usually it's not fatal. Its basically
like driving a car.

I knew about the one hand in pocket technique. The radio has exposed
fahnestock clips for the power, so I'll have to be really careful,
applying power only when my hands are clear, and keeping the cats out
of the room when operating the set. Would the set have hum powered
from these switch mode power supplys? I have a 2200 MFD 50 volt cap I
can use for a filter cap if needed.
Click to expand...
Jon,

Just FYI, I've measured the current in the 9V-to-tongue experiment at
about 1 or 2 mA. YMMV.

Mark
 
On Tue, 18 Mar 2008 21:14:22 -0700 (PDT), "Dave.H"
<the1930s@googlemail.com> wrote:

I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks

Dave
Click to expand...
48 volts is the usual legal limit for safe, low voltage [1]. If you
grabbed both wires, you might feel a tingle, but no big deal. Try it.

I tried a dc supply, holding banana leads firmly in two hands, and it
got uncomfortable around 90 volts or so.

Batteries would be no different.

John

[1] except for the new EU Low Voltage directive, which has no safe low
limit.
 
"Dave.H" (the1930s@googlemail.com) writes:
I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks

Dave
Click to expand...
Shocks are a total of the voltage, the current, the state of your
body and even how you touch the voltage.

It's "safe" to touch much higher voltage, if by safe you mean "not fatal".
On the other hand, when it happened to me a few times decades ago, I realized
I didn't want it to happen again, especially not after I hurt my arm (though
not-seriously) when my hand jumped off the high voltage and banged against
a hard surface.

For someone else, that voltage might have been fatal. Or, if it had gone
from one hand to the other, rather than from the finger to the side of my
hand that was about what happened.

The 9v batteries in series can be as dangerous as a 45volt power supply (or
as "safe"), the voltage is the same. The current of the power supply is
likely more, but then few think about the potential danger of running 12v
through their body at really high current.

"Safety" is also relative given the care you take. If you never touch
the voltage, you will always be safe no matter what the voltage or current.
But if you're careless, the safety starts disappearing.

Michael
 
"Dave.H" (the1930s@googlemail.com) writes:
On Mar 19, 5:36 pm, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com> wrote:
"Dave.H" <the19...@googlemail.com> wrote in message

news:bc083361-8e07-4b96-a1c7-940cb8bc97c3@d4g2000prg.googlegroups.com...

I'm not sure if I should be asking this this type of question here,
but couldn't find another suitable newsgroup, so here goes, I'm
building a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA. I'm not sure if this type of voltage and current is
dangerous, what would happen if I accidentally touched both the B+
line and the B- line, or ground connection at the same time? Would I
just receive a small electric shock? If it's too dangerous, I'll just
stick to 5, 9 volt batteries in series.
Thanks

In general that amount of voltage will not do anything. Even 120 is usually
not lethal in most circumstances(I don't mean that you go around playing
with it but I mean in most accidents when people get shocked).

At around 50V or more is when there is enough voltage to start to break
through the skin. Your skin is essentially like a resistive coating. It has
a high resistance but is thin. If the skin is wet or broken(With fluids)
then its worse Dry skin has about 500kOhm resistance so its no big deal. (at
100V thats only 0.2mA which is not enough to kill)

Wet skin is like 1kOhm so its 500 times more likely to get shocked if your
wet. This means its about 100mA(@100V) and enough to kill if it goes through
your heart.

Note though that the current does not flow ont he surface of your skin but
goes into your fluids where there are electrolytes and its much less
resistive(essentially your veins are like copper wires and your skin like a
resistor).

This is why the 9V shocks your tonge. Its probably sending an aweful lot of
current(probably 50mA is my guess on average) but does nothing because its
only on your tonge. (although I imagine a 9V can kill if placed "across the
heart".

The real issue is not shock. Its getting shocked in such a way that current
passes through your heart. (although serious burns can occur otherwise but
its usually rare)

The trick in working with "high voltage" is never to use two hands. The
reason why most people who die from electric shock is because they use two
hands and current will flow from one hand, through the blood into the heart
then out the other hand. Use one hand and probably at most you'll get
shocked. You can also wear some gloves if your still afraid. (even with one
hand its possible the current will go through your heart but much less
likely. If the other parts of your body are not being grounded in any way
then it's usually ok)

Main's is much worse because ground is earth ground. If you are working on a
power supply then you usually use a transformer and the only way to get
shocked is for your body to make a circuit with the ground on the secondary
side. This is pretty much impossible(except on your hand) if you keep one
hand away. (although there are allways accidents)

I think as long as you are careful then it will be ok. Its about 30kV/cm for
voltage to be able to "get you" through air. This means at 100V its only
like 33um. (about the size of a human hair)

The main thing is to just think about what your doing and don't be clumsy.
If you pay attention to what your doing and know the dangers and what is
dangerous in what your trying to measure then usually you'll be ok. Then, in
the rare chance that you get shocked usually it's not fatal. Its basically
like driving a car.

I knew about the one hand in pocket technique. The radio has exposed
fahnestock clips for the power, so I'll have to be really careful,
applying power only when my hands are clear, and keeping the cats out
of the room when operating the set. Would the set have hum powered
from these switch mode power supplys? I have a 2200 MFD 50 volt cap I
can use for a filter cap if needed.
Click to expand...
But that open style that was common in the early days is dangerous. One
famous Australian ham died a long time ago when he was doing something and
his headphones brushed against some high voltage, and he was known for his
techical writing so he should have known better.

Exposed wiring makes things a lot more dangerous than the voltage or
curent of the power supply. It's just too easy to accidentally brush against
something.

It isn't a joke, I have seen stories about people's cats dying when they
brush against high voltage, and the only reason that can happen is because
the high voltage isn't properly kept inside a box.

Michael
 
On 19 Mar 2008 14:25:19 GMT, et472@FreeNet.Carleton.CA (Michael Black)
wrote:


The 9v batteries in series can be as dangerous as a 45volt power supply (or
as "safe"), the voltage is the same. The current of the power supply is
likely more, but then few think about the potential danger of running 12v
through their body at really high current.
Click to expand...
How would one go about running 12 volts through their body at really
high current?

John
 
"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:9rb2u35c4g77fpfi6qf3aio3r97b0eopi7@4ax.com...
On 19 Mar 2008 14:25:19 GMT, et472@FreeNet.Carleton.CA (Michael Black)
wrote:


The 9v batteries in series can be as dangerous as a 45volt power supply
(or
as "safe"), the voltage is the same. The current of the power supply is
likely more, but then few think about the potential danger of running 12v
through their body at really high current.

How would one go about running 12 volts through their body at really
high current?

John
Click to expand...
Use two needles stuck into your veins. You will probably get enough current
to cause serious shock or even death if placed properly.

For the OP's circuit, with either batteries or wall-warts (especially with
a big capacitor), it might be good to rig up a simple current limiter, for
about 5-10 mA, and enclose the whole thing in an insulated box.

An LTspice schematic follows. It limits short circuit current to about 5
mA, but provides 44.6 VDC into a 10 kOhm load or higher. However, it draws
a constant 93 uA from the battery. You can fiddle with the values, and
maybe use a darlington (but you need to add an extra diode). It is also
possible to build this with a PMOS transistor with negligible current draw
with no load, but a little more power in the sense resistor while
operating.

Paul

========================================================

Version 4
SHEET 1 880 680
WIRE -16 160 -80 160
WIRE 0 160 -16 160
WIRE 160 160 80 160
WIRE 368 160 256 160
WIRE 400 160 368 160
WIRE -80 240 -80 160
WIRE -16 240 -16 160
WIRE 0 240 -16 240
WIRE 112 240 64 240
WIRE 208 240 208 224
WIRE 208 240 176 240
WIRE 400 240 400 160
WIRE 208 272 208 240
WIRE -80 400 -80 320
WIRE 208 400 208 352
WIRE 208 400 -80 400
WIRE 400 400 400 320
WIRE 400 400 208 400
WIRE -80 432 -80 400
FLAG -80 432 0
FLAG 368 160 Vout
SYMBOL Misc\\battery -80 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 132 Left 0
SYMATTR InstName V1
SYMATTR Value 45
SYMATTR SpiceLine Rser=1
SYMBOL pnp 256 224 M270
SYMATTR InstName Q1
SYMATTR Value 2N5401
SYMBOL res -16 176 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 0 56 VBottom 0
SYMATTR InstName R1
SYMATTR Value 47
SYMBOL res 192 256 R0
SYMATTR InstName R2
SYMATTR Value 470k
SYMBOL res 416 336 R180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL diode 0 256 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 112 256 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D2
SYMATTR Value 1N4148
TEXT -114 506 Left 0 !.tran .01 startup
 
On Mar 18, 9:14 pm, "Dave.H" <the19...@googlemail.com> wrote:
... a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA.  
Click to expand...
That's not normally a hazardous voltage (try not to touch
when wet, though). The easiest solution is a 24VAC wallwart,
feeding a voltage doubler rectifier.

Bad ASCII art follows:


+---|>|-+
| |
AC+---+---)|--+--+----|>|----+-----(B+ out)
+ | | +
| ---
--- ---
/ \ |
-+- |
| |
GND+-------------+-----------+-----


The clamp diode across the top right is optional. For 300 mA
output, capacitors should be at least 220 uF.
 
On Mar 19, 12:57 pm, whit3rd <whit...@gmail.com> wrote:


The clamp diode across the top right is optional.
Click to expand...
Oops. That should be 'diode across the top LEFT is optional.'
 
On Mar 20, 6:57 am, whit3rd <whit...@gmail.com> wrote:
On Mar 18, 9:14 pm, "Dave.H" <the19...@googlemail.com> wrote:

... a power supply for a regen radio that consists of two
wallwarts, in series delivering 23 volts 300 mA each, for a total of
46 volts, 300 mA.

That's not normally a hazardous voltage (try not to touch
when wet, though). The easiest solution is a 24VAC wallwart,
feeding a voltage doubler rectifier.

Bad ASCII art follows:

+---|>|-+
| |
AC+---+---)|--+--+----|>|----+-----(B+ out)
+ | | +
| ---
--- ---
/ \ |
-+- |
| |
GND+-------------+-----------+-----

The clamp diode across the top right is optional. For 300 mA
output, capacitors should be at least 220 uF.
Click to expand...
Thanks but I already have the two wall warts, and the parts to build a
little box that allows me to connect them in series without cutting
the DC plug off.
 
On Wed, 19 Mar 2008 14:37:26 -0400, "Paul E. Schoen"
<pstech@smart.net> wrote:

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:9rb2u35c4g77fpfi6qf3aio3r97b0eopi7@4ax.com...
On 19 Mar 2008 14:25:19 GMT, et472@FreeNet.Carleton.CA (Michael Black)
wrote:


The 9v batteries in series can be as dangerous as a 45volt power supply
(or
as "safe"), the voltage is the same. The current of the power supply is
likely more, but then few think about the potential danger of running 12v
through their body at really high current.

How would one go about running 12 volts through their body at really
high current?

John

Use two needles stuck into your veins. You will probably get enough current
to cause serious shock or even death if placed properly.
Click to expand...
Or you could get an infection, and die from that. A 12-volt car
battery can kill you, if dropped from a sufficient height.

For the OP's circuit, with either batteries or wall-warts (especially with
a big capacitor), it might be good to rig up a simple current limiter, for
about 5-10 mA, and enclose the whole thing in an insulated box.

An LTspice schematic follows. It limits short circuit current to about 5
mA, but provides 44.6 VDC into a 10 kOhm load or higher. However, it draws
a constant 93 uA from the battery. You can fiddle with the values, and
maybe use a darlington (but you need to add an extra diode). It is also
possible to build this with a PMOS transistor with negligible current draw
with no load, but a little more power in the sense resistor while
operating.
Click to expand...

Paranoia.


John
 
"Jon Slaughter" <Jon_Slaughter@Hotmail.com> wrote in message
news:nv2Ej.18924$xq2.16170@newssvr21.news.prodigy.net...
<snip>
The real issue is not shock. Its getting shocked in such a way that
current passes through your heart. (although serious burns can occur
otherwise but its usually rare)
Click to expand...
<snip>

There is a real difference between AC and DC wrt current across the heart.
DC, even in very high voltages, has the effect of clenching the muscles. So,
a DC shock may stop your heart, but only when you are holding it. If you can
let go,, you are probably going to be OK.

On the other hand, AC has the effect of putting the heart into fibrillation.
This is often lethal, and actually used to be treated by passing a DC
current (by charging big caps up to 1000V!) across the heart, which stops it
and resets it. They now use a sine waveform (which is AC, actually, but is
about 100Hz) that uses less energy, and thus causes less damage.

The upshot is that 50VDC isn't going to hurt you.

Regards,
Bob Monsen
 
"Bob Monsen" <rcmonsen@gmail.com> wrote in message
news:sZxEj.4551$qS5.3503@nlpi069.nbdc.sbc.com...
"Jon Slaughter" <Jon_Slaughter@Hotmail.com> wrote in message
news:nv2Ej.18924$xq2.16170@newssvr21.news.prodigy.net...
snip

The real issue is not shock. Its getting shocked in such a way that
current passes through your heart. (although serious burns can occur
otherwise but its usually rare)


snip

There is a real difference between AC and DC wrt current across the heart.
DC, even in very high voltages, has the effect of clenching the muscles.
So, a DC shock may stop your heart, but only when you are holding it. If
you can let go,, you are probably going to be OK.

On the other hand, AC has the effect of putting the heart into
fibrillation. This is often lethal, and actually used to be treated by
passing a DC current (by charging big caps up to 1000V!) across the heart,
which stops it and resets it. They now use a sine waveform (which is AC,
actually, but is about 100Hz) that uses less energy, and thus causes less
damage.

The upshot is that 50VDC isn't going to hurt you.
Click to expand...
It doesn't really matter. If you get shocked through the heart by DC there
is much more likely to be serious injury to the muscles and blood vessles
than with ac. Also, if the DC is high enough you can actually create an
electrolytic effect in the blood stream.


Would you rather get ran over with a tank or hit by a plane? Either way
your dead so it does't matter much. (also 50VDC is not 50VAC rms so you
can't compare them directly)

I would aggree that AC probably has a higher chance causing fibrillation
than DC because of the way the heart is designed. But I would imagine that
chances are if you get shocked with DC power or equal AC power across the
heart that both with have approximately the same outcome. (although I
really have no idea exactly how they are related. AC may be worse at low
voltages than DC and maybe DC is worse at high)
 
"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:0lu4u3ljlh3oegri93ms0inejo5g19vug5@4ax.com...
On Wed, 19 Mar 2008 14:37:26 -0400, "Paul E. Schoen"
pstech@smart.net> wrote:


"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in
message
news:9rb2u35c4g77fpfi6qf3aio3r97b0eopi7@4ax.com...
On 19 Mar 2008 14:25:19 GMT, et472@FreeNet.Carleton.CA (Michael Black)
wrote:


The 9v batteries in series can be as dangerous as a 45volt power supply
(or
as "safe"), the voltage is the same. The current of the power supply
is
likely more, but then few think about the potential danger of running
12v
through their body at really high current.

How would one go about running 12 volts through their body at really
high current?

John

Use two needles stuck into your veins. You will probably get enough
current
to cause serious shock or even death if placed properly.

Or you could get an infection, and die from that. A 12-volt car
battery can kill you, if dropped from a sufficient height.
Click to expand...
And a fully discharged AAA cell can kill you if fired from a gun. Or if you
eat enough of them. :)

For the OP's circuit, with either batteries or wall-warts (especially
with
a big capacitor), it might be good to rig up a simple current limiter,
for
about 5-10 mA, and enclose the whole thing in an insulated box.

An LTspice schematic follows. It limits short circuit current to about 5
mA, but provides 44.6 VDC into a 10 kOhm load or higher. However, it
draws
a constant 93 uA from the battery. You can fiddle with the values, and
maybe use a darlington (but you need to add an extra diode). It is also
possible to build this with a PMOS transistor with negligible current
draw
with no load, but a little more power in the sense resistor while
operating.


Paranoia.
Click to expand...
Not at all. It's a good idea, at least, to know how to rig up a current
limiter, especially when it can be built for less than the cost of one of
the batteries. It could prolong their life in the case of an accidental
short circuit or overload, and it would be very much advisable for Lithium
batteries which can explode if short-circuited.

Here's the MOSFET version, using only four cheap parts:

Paul

============================================================

Version 4
SHEET 1 880 680
WIRE -16 160 -80 160
WIRE 0 160 -16 160
WIRE 160 160 80 160
WIRE 368 160 256 160
WIRE 400 160 368 160
WIRE -80 240 -80 160
WIRE -16 240 -16 160
WIRE 48 240 -16 240
WIRE 176 240 176 208
WIRE 176 240 112 240
WIRE 208 240 176 240
WIRE 400 240 400 160
WIRE 208 272 208 240
WIRE -80 400 -80 320
WIRE 208 400 208 352
WIRE 208 400 -80 400
WIRE 400 400 400 320
WIRE 400 400 208 400
WIRE -80 432 -80 400
FLAG -80 432 0
FLAG 368 160 Vout
SYMBOL Misc\\battery -80 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 132 Left 0
SYMATTR InstName V1
SYMATTR Value 45
SYMATTR SpiceLine Rser=1
SYMBOL res -16 176 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 0 56 VBottom 0
SYMATTR InstName R1
SYMATTR Value 470
SYMBOL res 192 256 R0
SYMATTR InstName R2
SYMATTR Value 22Meg
SYMBOL res 416 336 R180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL pmos 256 208 M270
SYMATTR InstName M1
SYMATTR Value IRF9Z24S_L
SYMBOL zener 112 256 M270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D1
SYMATTR Value BZX84C6V2L
SYMATTR Description Diode
SYMATTR Type diode
TEXT -114 506 Left 0 !.tran .01 startup
 
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