Old jug element makes good dummy load?

[Franc Zabkar]

My old $10 electric jug finally failed due to arcing at the mains
socket. However the 2200W 240V heating element is still serviceable.
It occurred to me that it may be useful as a dummy load. Some
searching revealed that others have had the same idea.

My own element has a resistance of 27R to 28R which I suppose could be
used as a 1A load on a 24V supply. In the USA, a 120V 1500W element
would have a resistance of 9.6 ohms which may be close enough for
testing audio amplifiers. You wouldn't need to dismantle two working
jugs. Instead you could chop off the mains plug and connect the bare
wires to the amp's speaker terminals, or you could make an adapter
using a mains socket and a short length of cord. The dummy load would
be water cooled, and you could have a cup of coffee when you finished
testing.

====================================================================
This was my 4th attempt at posting this message. Astraweb appears to
have some kind of filter bot in place.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[hr(bob) hofmann@att.net]

On Dec 19, 3:05 pm, Franc Zabkar <fzab...@iinternode.on.net> wrote:

My old $10 electric jug finally failed due to arcing at the mains
socket. However the 2200W 240V heating element is still serviceable.
It occurred to me that it may be useful as a dummy load. Some
searching revealed that others have had the same idea.

My own element has a resistance of 27R to 28R which I suppose could be
used as a 1A load on a 24V supply. In the USA, a 120V 1500W element
would have a resistance of 9.6 ohms which may be close enough for
testing audio amplifiers. You wouldn't need to dismantle two working
jugs. Instead you could chop off the mains plug and connect the bare
wires to the amp's speaker terminals, or you could make an adapter
using a mains socket and a short length of cord. The dummy load would
be water cooled, and you could have a cup of coffee when you finished
testing.

===================================================================> This was my 4th attempt at posting this message. Astraweb appears to
have some kind of filter bot in place.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

For someone on the west side of the big pond, what is an "electric
jug"?

 

[Franc Zabkar]

On Fri, 19 Dec 2008 15:21:26 -0800 (PST), "hr(bob) hofmann@att.net"
<hrhofmann@att.net> put finger to keyboard and composed:

For someone on the west side of the big pond, what is an "electric
jug"?

Electric kettle.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[Bill Janssen]

Franc Zabkar wrote:

My old $10 electric jug finally failed due to arcing at the mains
socket. However the 2200W 240V heating element is still serviceable.
It occurred to me that it may be useful as a dummy load. Some
searching revealed that others have had the same idea.

My own element has a resistance of 27R to 28R which I suppose could be
used as a 1A load on a 24V supply. In the USA, a 120V 1500W element
would have a resistance of 9.6 ohms which may be close enough for
testing audio amplifiers. You wouldn't need to dismantle two working
jugs. Instead you could chop off the mains plug and connect the bare
wires to the amp's speaker terminals, or you could make an adapter
using a mains socket and a short length of cord. The dummy load would
be water cooled, and you could have a cup of coffee when you finished
testing.


If the heating element is made from a spring shaped resistance it may

have too much
inductance to be usable for some purposes. You might want to measure for
inductance.

Bill K7NOM

 

[Allodoxaphobia]

On Sat, 20 Dec 2008 11:10:19 +1100, Franc Zabkar wrote:

On Fri, 19 Dec 2008 15:21:26 -0800 (PST), "hr(bob) hofmann@att.net"
hrhofmann@att.net> put finger to keyboard and composed:

For someone on the west side of the big pond, what is an "electric
jug"?

Electric kettle.

Crock Pot

 

[N_Cook]

Allodoxaphobia <bit-bucket@config.com> wrote in message
news:slrngkolu1.2ofo.bit-bucket@shell.config.com...

On Sat, 20 Dec 2008 11:10:19 +1100, Franc Zabkar wrote:
On Fri, 19 Dec 2008 15:21:26 -0800 (PST), "hr(bob) hofmann@att.net"
hrhofmann@att.net> put finger to keyboard and composed:

For someone on the west side of the big pond, what is an "electric
jug"?

Electric kettle.

Crock Pot

Surely that goes back to the stone-age, literally, certainly before metal
and fireproof clay cook-pots became available, let alone electric.
Crocks or stones are heated in a fire and then transfered with split twig to
a wooden bowl of cold water.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Franc Zabkar]

On Fri, 19 Dec 2008 16:41:52 -0800, Bill Janssen <billj@ieee.org> put
finger to keyboard and composed:

Franc Zabkar wrote:
My old $10 electric jug finally failed due to arcing at the mains
socket. However the 2200W 240V heating element is still serviceable.
It occurred to me that it may be useful as a dummy load.

If the heating element is made from a spring shaped resistance it may
have too much
inductance to be usable for some purposes. You might want to measure for
inductance.

Bill K7NOM

The element I'm thinking of is not the exposed nichrome (?) wire type.
Instead it looks something like this:
http://www.sparepairs.com.au/images/website%20product%20photos%209%20008.jpg

I don't know what the internal construction is like, but its
inductance does not register on my DMM's 2mH (milliHenry) scale. It
measures 26.8 ohms on my DMM, and between 27 and 28 ohms on Bob
Parker's ESR meter.

Here are several measurements of real speakers that I made using the
latter:
http://groups.google.com/group/sci.electronics.repair/msg/809b54899b52d13c?dmode=source

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[Arfa Daily]

"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:so2ok4l6glpn1fj5nkh2evb4g3qb7loq5c@4ax.com...

My old $10 electric jug finally failed due to arcing at the mains
socket. However the 2200W 240V heating element is still serviceable.
It occurred to me that it may be useful as a dummy load. Some
searching revealed that others have had the same idea.

My own element has a resistance of 27R to 28R which I suppose could be
used as a 1A load on a 24V supply. In the USA, a 120V 1500W element
would have a resistance of 9.6 ohms which may be close enough for
testing audio amplifiers. You wouldn't need to dismantle two working
jugs. Instead you could chop off the mains plug and connect the bare
wires to the amp's speaker terminals, or you could make an adapter
using a mains socket and a short length of cord. The dummy load would
be water cooled, and you could have a cup of coffee when you finished
testing.

====================================================================
This was my 4th attempt at posting this message. Astraweb appears to
have some kind of filter bot in place.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

I use 12v 20w and 50w halogen bulbs as dummy loads on power supplies, for
instance when I'm repairing LCD TV PSUs which output 24v at around 4 amps
for the backlights. I just hook them in series and parallel as required. A
couple of extra 'advantages' are that the low resistance when they are cold
does a good job of simulating the current surge that a 'real' backlight
inverter pulls when it strikes the tubes up, and the light output from the
lamps is a good indicator that the PSU is still running, when you are
leaving up the corner on extended soak test.

I've never tried one as an RF dummy load, but given that some of the low
power CB dummy loads from way back were just a small flashlamp-type bulb
grafted into a PL259 plug, I guess it might be worth dusting off my power
and SWR meters, to see what they are like. Might also be worth doing some
experiments at audio, although I do have a totally resistive high power load
that I normally use for testing.

Arfa