This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls into a special category (5 bands, fourth band silver) so I'm not confident about deciding it.

What is it?

Tim

On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls into a special category (5 bands, fourth band silver) so I'm not confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

it *ought* to be 39 ohms 5% 100ppm/°k
But I would have expected that to be orange white black silver brownm.

https://www.arrow.com/en/research-an...tor-color-code


--
€œA leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
€œWe did this ourselves.€�

ۥ Lao Tzu, Tao Te Ching

On Monday, October 7, 2019 at 5:45:42 PM UTC+1, The Natural Philosopher wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls into a special category (5 bands, fourth band silver) so I'm not confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

Maybe I've read them in reverse? Anyhow, I *did* post a link to a picture...


Tim

On 07/10/2019 17:48, Tim+ wrote:
On Monday, October 7, 2019 at 5:45:42 PM UTC+1, The Natural Philosopher wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls into a special category (5 bands, fourth band silver) so I'm not confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

Maybe I've read them in reverse? Anyhow, I *did* post a link to a picture...


Tim

I cant tell if the bands are white or silver and whether the end band is
red or brown.

Cameras are not that hot on colour sometimes



--
€œIdeas are inherently conservative. They yield not to the attack of
other ideas but to the massive onslaught of circumstance"

- John K Galbraith

The Natural Philosopher wrote:
On 07/10/2019 17:48, Tim+ wrote:
On Monday, October 7, 2019 at 5:45:42 PM UTC+1, The Natural Philosopher wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

Maybe I've read them in reverse? Anyhow, I *did* post a link to a picture...


Tim

I cant tell if the bands are white or silver and whether the end band is
red or brown.

Cameras are not that hot on colour sometimes




Second one down from the top is definitely silver. Top band looks brown to
me but Im no expert at reading these.

Tim

--
Please don't feed the trolls

On 07/10/19 17:45, The Natural Philosopher wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls into a special category (5 bands, fourth band silver) so I'm not confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

it *ought* to be 39 ohms 5% 100ppm/°k
But I would have expected that to be orange white black silver brownm.

https://www.arrow.com/en/research-an...tor-color-code

Silver tolerance is 10%, not 5%. Other than that, agreed it's as you say.

--

Jeff

On 07/10/2019 17:45, The Natural Philosopher wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

it *ought* to be 39 ohms 5% 100ppm/°k
But I would have expected that to be orange white black silver brownm.

https://www.arrow.com/en/research-an...tor-color-code

I reckon silver is the multiplier x0.01 and it is actually 0.39 ohm.
E12 value shifted along with a leading zero Not seen one before.
Red or brown is probably the tolerance.

Most of my small power resistors have the value in small type face.

--
Regards,
Martin Brown

On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls into a special category (5 bands, fourth band silver) so I'm not confident about deciding it.

What is it?

Tim

039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown. (I use R for ohms)

Cheers
--
Clive

On 07/10/2019 18:23, Clive Arthur wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown.Â* (I use R for ohms)

Cheers
Yes, my thoughts too. Don't see silver or gold multipliers too often.


Confirmed by this site.

https://www.digikey.se/en/resources/...or-code-5-band

On 07/10/19 18:31, mm0fmf wrote:
On 07/10/2019 18:23, Clive Arthur wrote:


039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown.Â* (I use R for ohms)

Cheers
Yes, my thoughts too. Don't see silver or gold multipliers too often.


Confirmed by this site.

https://www.digikey.se/en/resources/...or-code-5-band

Yes, you are right - it's not 39 ohms. That's a useful webpage

--

Jeff

On 07/10/2019 18:23, Clive Arthur wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown.Â* (I use R for ohms)

Cheers

I'd write that as 0R39, just as I'd write 4.7Kohm as 4K7

SteveW

On 07/10/2019 21:46, Steve Walker wrote:
On 07/10/2019 18:23, Clive Arthur wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it
falls into a special category (5 bands, fourth band silver) so I'm
not confident about deciding it.

What is it?

Tim

039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown.Â* (I use R for ohms)

Cheers

I'd write that as 0R39, just as I'd write 4.7Kohm as 4K7

SteveW

You'd be wrong then. Should be 4k7, it's kilo not Kelvins.

Cheers
--
Clive

On Mon, 07 Oct 2019 18:11:49 +0100, Jeff Layman wrote:

On 07/10/19 17:45, The Natural Philosopher wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

it *ought* to be 39 ohms 5% 100ppm/°k But I would have expected that to
be orange white black silver brownm.

https://www.arrow.com/en/research-an...esistor-color-
code

Silver tolerance is 10%, not 5%. Other than that, agreed it's as you
say.

The silver isn't a tolerance. It's a multiplier.



--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

On 07/10/2019 23:24, Clive Arthur wrote:
On 07/10/2019 21:46, Steve Walker wrote:
On 07/10/2019 18:23, Clive Arthur wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it
falls into a special category (5 bands, fourth band silver) so I'm
not confident about deciding it.

What is it?

Tim

039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown.Â* (I use R for ohms)

Cheers

I'd write that as 0R39, just as I'd write 4.7Kohm as 4K7

SteveW

You'd be wrong then. Should be 4k7, it's kilo not Kelvins.

In the first case yes - I mis-typed a capital K, while pre-occupied with
why Windows has changed some of the Alt/Numeric combinations, but not
others (ALT-248 still gives degrees, but ALT-234 apparently no longer
gives the ohms symbol and ALT-0937 doesn't either)`. It seems odd to
change something that has been around since DOS days, when most of it
seems unchanged.

In the second case, many circuit diagrams and technical drawings
traditionally use only upper case letters and would normally use 4K7
rather than 4k7, so either is acceptable there.

SteveW

On 07/10/2019 23:42, Steve Walker wrote:
On 07/10/2019 23:24, Clive Arthur wrote:
On 07/10/2019 21:46, Steve Walker wrote:
On 07/10/2019 18:23, Clive Arthur wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it
falls into a special category (5 bands, fourth band silver) so I'm
not confident about deciding it.

What is it?

Tim

039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown.Â* (I use R for ohms)

Cheers

I'd write that as 0R39, just as I'd write 4.7Kohm as 4K7

SteveW

You'd be wrong then. Should be 4k7, it's kilo not Kelvins.

In the first case yes - I mis-typed a capital K, while pre-occupied with
why Windows has changed some of the Alt/Numeric combinations, but not
others (ALT-248 still gives degrees, but ALT-234 apparently no longer
gives the ohms symbol and ALT-0937 doesn't either)`. It seems odd to
change something that has been around since DOS days, when most of it
seems unchanged.

In the second case, many circuit diagrams and technical drawings
traditionally use only upper case letters and would normally use 4K7
rather than 4k7, so either is acceptable there.

Then there are those times when an AK47 is more than enough...

I cannot see the value, but maybe its a vdr that has dumped an over voltage
and been destroyed. One reallly needs the circuit, otherwise all would be
guesswork, but its going to be quite a low ohmage since to burn out anything
bigger would need more volts, assuming its not on the mains supply side.
Brian

--
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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"The Natural Philosopher" wrote in message
...
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

it *ought* to be 39 ohms 5% 100ppm/°k
But I would have expected that to be orange white black silver brownm.

https://www.arrow.com/en/research-an...tor-color-code


--
"A leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
"We did this ourselves."

? Lao Tzu, Tao Te Ching

It sounds jolly non standard to me.
Brian

--
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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Bob Eager" wrote in message
...
On Mon, 07 Oct 2019 18:11:49 +0100, Jeff Layman wrote:

On 07/10/19 17:45, The Natural Philosopher wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

it *ought* to be 39 ohms 5% 100ppm/°k But I would have expected that to
be orange white black silver brownm.

https://www.arrow.com/en/research-an...esistor-color-
code

Silver tolerance is 10%, not 5%. Other than that, agreed it's as you
say.

The silver isn't a tolerance. It's a multiplier.



--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

Yes but a resistor of that value is normally a more high wattage device.
What would one have such a low value for in such a low wattage, since the
ruddy power cable is a fair percentage of that. One would not use a fusable
resistor these days.
Brian

--
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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Martin Brown" wrote in message
...
On 07/10/2019 17:45, The Natural Philosopher wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

it *ought* to be 39 ohms 5% 100ppm/°k
But I would have expected that to be orange white black silver brownm.

https://www.arrow.com/en/research-an...tor-color-code

I reckon silver is the multiplier x0.01 and it is actually 0.39 ohm.
E12 value shifted along with a leading zero Not seen one before.
Red or brown is probably the tolerance.

Most of my small power resistors have the value in small type face.

--
Regards,
Martin Brown

However, going back to the original thread on this, 1, how many wires are in
the cable to the laptop?
If its only two, have you actually ascertained there is no damage to this
cable, ie a short?
If yes, do we still not know if it is switch mode or not, I'd really be
surprised if its analogue myself, which then makes me suspect that its
terminally damaged, as many of these use a custom chip and maybe a couple of
high voltage semiconductors and a ridiculously tiny transformer, followed
by fairly conventional circuitry but they need quite a lot of filtering.
Many do have a feedback network to maintain current or voltage, and some
have a multicore cable to allow the charging circuit to mostly be in the
psu, but not always.
If the mac book is a good recent model, for goodness sake by a real apple
replacement for the thing or you might brick the laptop.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Richard" wrote in message
...
On 07/10/2019 23:42, Steve Walker wrote:
On 07/10/2019 23:24, Clive Arthur wrote:
On 07/10/2019 21:46, Steve Walker wrote:
On 07/10/2019 18:23, Clive Arthur wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it
falls into a special category (5 bands, fourth band silver) so I'm
not confident about deciding it.

What is it?

Tim

039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown. (I use R for ohms)

Cheers

I'd write that as 0R39, just as I'd write 4.7Kohm as 4K7

SteveW

You'd be wrong then. Should be 4k7, it's kilo not Kelvins.

In the first case yes - I mis-typed a capital K, while pre-occupied with
why Windows has changed some of the Alt/Numeric combinations, but not
others (ALT-248 still gives degrees, but ALT-234 apparently no longer
gives the ohms symbol and ALT-0937 doesn't either)`. It seems odd to
change something that has been around since DOS days, when most of it
seems unchanged.

In the second case, many circuit diagrams and technical drawings
traditionally use only upper case letters and would normally use 4K7
rather than 4k7, so either is acceptable there.

Then there are those times when an AK47 is more than enough...

Brian Gaff wrote

I cannot see the value, but maybe its a vdr

No its not.

that has dumped an over voltage and been destroyed.

It looks fine.

One reallly needs the circuit,

No you don’t if its open circuit.

otherwise all would be guesswork,

Not if its open circuit.

but its going to be quite a low ohmage since to
burn out anything bigger would need more volts,

It doesn’t appear to be burnt out from the picture.

assuming its not on the mains supply side.


"The Natural Philosopher" wrote in message
...
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

it *ought* to be 39 ohms 5% 100ppm/°k
But I would have expected that to be orange white black silver brownm.

https://www.arrow.com/en/research-an...tor-color-code


--
"A leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
"We did this ourselves."

? Lao Tzu, Tao Te Ching

On 07/10/2019 18:00, Tim+ wrote:
The Natural Philosopher wrote:
On 07/10/2019 17:48, Tim+ wrote:
On Monday, October 7, 2019 at 5:45:42 PM UTC+1, The Natural Philosopher wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

What are the colours? it not sane to have the first band as black=0

Maybe I've read them in reverse? Anyhow, I *did* post a link to a picture...


Tim

I cant tell if the bands are white or silver and whether the end band is
red or brown.

Cameras are not that hot on colour sometimes




Second one down from the top is definitely silver. Top band looks brown to
me but Im no expert at reading these.

Well that would appear to be a 10% tlrenmace with te briwn band being te
temerature coefficient.
The other bands dont make sense though.

looks like black orange white which is 039 with no multplier.

Tim



--
€œit should be clear by now to everyone that activist environmentalism
(or environmental activism) is becoming a general ideology about humans,
about their freedom, about the relationship between the individual and
the state, and about the manipulation of people under the guise of a
'noble' idea. It is not an honest pursuit of 'sustainable development,'
a matter of elementary environmental protection, or a search for
rational mechanisms designed to achieve a healthy environment. Yet
things do occur that make you shake your head and remind yourself that
you live neither in Joseph Stalins Communist era, nor in the Orwellian
utopia of 1984.€�

Vaclav Klaus

On 07/10/2019 21:46, Steve Walker wrote:
On 07/10/2019 18:23, Clive Arthur wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it
falls into a special category (5 bands, fourth band silver) so I'm
not confident about deciding it.

What is it?

Tim

039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown.Â* (I use R for ohms)

Cheers

I'd write that as 0R39, just as I'd write 4.7Kohm as 4K7

SteveW
Oooh you modernist!


--
There is nothing a fleet of dispatchable nuclear power plants cannot do
that cannot be done worse and more expensively and with higher carbon
emissions and more adverse environmental impact by adding intermittent
renewable energy.

On Tue, 8 Oct 2019 19:30:17 +1100, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

FLUSH the auto-contradicting sociopath's latest troll****

You don't give up easily, eh, you senile pest? Neither will I, punching bag!
BG

--
Website (from 2007) dedicated to the 85-year-old trolling senile
cretin from Oz:
https://www.pcreview.co.uk/threads/r...d-faq.2973853/

On 08/10/2019 08:07, Brian Gaff wrote:
Yes but a resistor of that value is normally a more high wattage device.
What would one have such a low value for in such a low wattage, since the
ruddy power cable is a fair percentage of that. One would not use a fusable
resistor these days.
Brian

It will be whatever wattage is needed for the circuit. Presumably
something has drawn a lot more current through it than it was rated for
so replacing it will merely kill another unfortunate 0.39R component.

Resistors in properly designed circuits seldom burn out unless something
else catastrophic has happened like a crowbar circuit across the PSU.

--
Regards,
Martin Brown

On 08/10/2019 08:07, Brian Gaff wrote:
Yes but a resistor of that value is normally a more high wattage device.
What would one have such a low value for in such a low wattage, since the
ruddy power cable is a fair percentage of that. One would not use a fusable
resistor these days.
Brian


Its probably a current sense resistor.

Something will be reading the voltage across it to control the feedback.

1A current will give 0.39V and about 400mW power dissipation.

It looks like a half watt resistor so I expect it to be something around
there.

Without a circuit that's about all I can say.

On Tuesday, 8 October 2019 08:04:57 UTC+1, Brian Gaff wrote:

Well it is from an Apple supply ;-)

I too think it's 0.39 or 0R39

and the black band is zero and probably there to itentify which end you use to start from 039 x 0.01 at 100ppm
rather than 1s930

The only resistors I have with a first band as black are some zero ohm resistors which just have one black band.

A lecturer has asked me if I can buy some 10% (silver band) tolernace resistors

It sounds jolly non standard to me.
Brian

whisky-dave wrote:

On Tuesday, 8 October 2019 08:04:57 UTC+1, Brian Gaff wrote:

Well it is from an Apple supply ;-)

I too think it's 0.39 or 0R39

and the black band is zero and probably there to itentify which end you
use to start from 039 x 0.01 at 100ppm rather than 1s930

As !% and better resistors generally have 3 digit bands, the leading
zero is probably to avoid having an even smaller negative index than
silver.



The only resistors I have with a first band as black are some zero ohm
resistors which just have one black band.

A lecturer has asked me if I can buy some 10% (silver band) tolernace
resistors

It sounds jolly non standard to me.
Brian



--

Roger Hayter

In article 5854d3fa-5450-496e-9f5b-


A lecturer has asked me if I can buy some 10% (silver band) tolernace resistors

Why does he want resistors with such a wide tolerance?

I haven't been responsible for ordering components regularly
sine 1969 (!) and I didn't have a resistor with a tolerance
worse than 5% in my entire stock even then.

Taking a qick look on-line to see what is available today:

https://cpc.farnell.com/c/electronic-electrical-
components/resistors/resistors-fixed-value/through-hole-
resistors

or https://tinyurl.com/y2oakfjb

I see lots of 0.25W 1% resistors for just over a penny each
and 5% values for half that so it isn't going to be an economy
measure!

L looked for 10% tolerance and only found 9 results - and they
are all 2W at 8p ea!

Interestingly, in 1969 I wasc paying 16/- (80p) for 100 0.5W
5% resistors so a pretty comparable price despite all the
rampant inflation in the intervening years!

Given that all my resistors were carbon film and the modern
ones are superior metal film, todays prices are a bargain!


--

Terry

--
This email has been checked for viruses by AVG.
https://www.avg.com

In article ,
Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

Since it looks to be in good condition, measure it? That can give clue to
what system they are using.

But it sounds typical Apple. Use any non standard thing they can
everywhere. ;-)

--
*What are the pink bits in my tyres? Cyclists & Joggers*

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article ,
Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

Since it looks to be in good condition, measure it? That can give clue to
what system they are using.

Um, the other side is burnt. Its fecked.

Tim

--
Please don't feed the trolls

On 08/10/2019 06:18, Richard wrote:
On 07/10/2019 23:42, Steve Walker wrote:
On 07/10/2019 23:24, Clive Arthur wrote:
On 07/10/2019 21:46, Steve Walker wrote:
On 07/10/2019 18:23, Clive Arthur wrote:
On 07/10/2019 17:32, Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it
falls into a special category (5 bands, fourth band silver) so I'm
not confident about deciding it.

What is it?

Tim

039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown.Â* (I use R for ohms)

Cheers

I'd write that as 0R39, just as I'd write 4.7Kohm as 4K7

SteveW

You'd be wrong then. Should be 4k7, it's kilo not Kelvins.

In the first case yes - I mis-typed a capital K, while pre-occupied
with why Windows has changed some of the Alt/Numeric combinations, but
not others (ALT-248 still gives degrees, but ALT-234 apparently no
longer gives the ohms symbol and ALT-0937 doesn't either)`. It seems
odd to change something that has been around since DOS days, when most
of it seems unchanged.

In the second case, many circuit diagrams and technical drawings
traditionally use only upper case letters and would normally use 4K7
rather than 4k7, so either is acceptable there.

Then there are those times when an AK47 is more than enough...

May I refer you to https://www.youtube.com/watch?v=lADSB7OK4n0

SteveW

"Tim+" wrote in message
...
Dave Plowman (News) wrote:
In article ,
Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

Since it looks to be in good condition, measure it? That can give clue to
what system they are using.

Um, the other side is burnt. Its fecked.

Thats unusual, one side of a power resistor burnt and the other perfect.

You sure it wasnt burnt by what it was next to ?

On Tue, 8 Oct 2019 13:14:00 +0100, "dennis@home"
wrote:

On 08/10/2019 08:07, Brian Gaff wrote:
Yes but a resistor of that value is normally a more high wattage device.
What would one have such a low value for in such a low wattage, since the
ruddy power cable is a fair percentage of that. One would not use a fusable
resistor these days.
Brian


Its probably a current sense resistor.

Something will be reading the voltage across it to control the feedback.

1A current will give 0.39V and about 400mW power dissipation.

It looks like a half watt resistor so I expect it to be something around
there.

Without a circuit that's about all I can say.


That's brilliant reasoning, and answers my puzzlement as to what it's
for. I can't see any damage in the photo, but it would take say 2A to
blow it up.
--
Dave W

On Wed, 9 Oct 2019 08:47:31 +1100, AlexK, better known as cantankerous
trolling senile geezer Rodent Speed, wrote:


Um, the other side is burnt. It¢s fecked.

That¢s unusual,

Not as unusual as a senile 85-year-old Australian asshole like you trolling
exclusively in UK ngs! You ARE clinically insane, senile *******!

--
Website (from 2007) dedicated to the 85-year-old trolling senile
cretin from Oz:
https://www.pcreview.co.uk/threads/r...d-faq.2973853/

On Tuesday, 8 October 2019 18:46:08 UTC+1, Terry Casey wrote:
In article 5854d3fa-5450-496e-9f5b-


A lecturer has asked me if I can buy some 10% (silver band) tolernace resistors

Why does he want resistors with such a wide tolerance?

She asked me because part of a lab is to test and understand tolorencies
and also the series of E values that are made for resistors although that was my idea. We also have to teach them the intricacies of power rating and what happens when these are exceeded. So in a lab it'd be nice to have these to test.
I actually remmeber 20% which IIRC had a pink band, they were 2W and had a sticky waxy feel to them.

Obviously the problem is how do you really test a 5% resistor with meters that are only accurate to 1-2%. I've tested a few 5% and it is suprising how accurate they are I don't think I've found one that is more than 3% out, and there's no way I'm going through my boxes of 1000 per value :-


I haven't been responsible for ordering components regularly
sine 1969 (!) and I didn't have a resistor with a tolerance
worse than 5% in my entire stock even then.

But don't forget this is a lecturer not someone that actually deals in such things in the real world. ;-)

Today we are running a lab titled Embeded Systems.
Which uses a freescale development board the first part shows them how to connect a push switch to the GPIO and then an LED off that.
The LED is shown in the diagram as connected to a 300 Ohm resistor the lecturer has even bothered to draw the resistor in place showing how to connect it up to a protoboard and the resistor with the colour code LtoR ! of Red Black Orange.

So I have 40 odd (very odd) students coming to me asking why I don't have any 300 ohm resistors.

One student was very proud of the fact of working out he could use 2 150R to make a 300R resistor, I did say he could use a 270R or a 330R and all that would do is change the brightness of the LED, I also said if he used the 330 then that would reduce the amount of current and help the world cut down on global warming and perhaps save trees too.
I've stopped a couple of them walking off with 330K resistors, as they weren't sure of the relivance of the R & K after the digits
But don't forget I'm not allowed to teach students, but I am allowed to and expected to impart my knowledge, which strangley enough doesn't warrent a salery scale increase.


Taking a qick look on-line to see what is available today:

https://cpc.farnell.com/c/electronic-electrical-
components/resistors/resistors-fixed-value/through-hole-
resistors

or https://tinyurl.com/y2oakfjb

This is what I buy
https://www.rapidonline.com/truohm-c...of-1000-561943


I see lots of 0.25W 1% resistors for just over a penny each
and 5% values for half that so it isn't going to be an economy
measure! a

I have bought some 1% t 100R 1K 10K 100K a few 0.1% 1K , 10K and a 50R and a 1K of 0.01% for £15 each for demonstrating to any inquisitive student or academic.

We do have a LCR meter that can measure resitors to 0.1% accuracy but as it was £1,400 we only have one making it difficult for up to 50 students per session to use.


L looked for 10% tolerance and only found 9 results - and they
are all 2W at 8p ea!

Yes and I'd need at least 50 of a few values and that is if students after using them didn't lose them, break them or eat them, which is why I've told the lecturer I don't keep 10% as they aren't really used/made in this millennium.


Interestingly, in 1969 I wasc paying 16/- (80p) for 100 0.5W
5% resistors so a pretty comparable price despite all the
rampant inflation in the intervening years!

I heard that in 1979 a blue LED retailed at £30 !
I leave them out in the lab for students to help themselves same as the red, yellow, green and white versions in both 5mm and 3mm sizes.



Given that all my resistors were carbon film and the modern
ones are superior metal film, todays prices are a bargain!

yes I agree and why I don't really want students putting them back in draws if the leads are damaged as puting them back into our protoboards can and does damage the contacts in the protoboards which are £10 each !
we orered 100 protoboard for this year, hopefully most will survive and can be reused next year.

On Tuesday, 8 October 2019 22:03:50 UTC+1, Steve Walker wrote:
On 08/10/2019 06:18, Richard wrote:


Then there are those times when an AK47 is more than enough...


I thought an AK-47 was a sort of semi automatic gun and AK47 was a strain of marijuana :-)

In article
,
Tim+ wrote:
Dave Plowman (News) wrote:
In article ,
Tim+ wrote:
This is the resistor from my macbook power supply.

It *look* to me to be black, orange, white (or grey), silver, brown.

https://photos.app.goo.gl/ZDY1qe8L3xKc4JBG8

I thought it would be easy to calculate the value but I think it falls
into a special category (5 bands, fourth band silver) so I'm not
confident about deciding it.

What is it?

Tim

Since it looks to be in good condition, measure it? That can give clue
to what system they are using.

Um, the other side is burnt. It‘s fecked.

OK. Although it would be difficult to measure a fraction of an ohm
accurately anyway.

Wonder if the heat cooked some of the colours? Because I can't see any
reason to start with a 0. Given resistors of less than 1 ohm ain't exactly
rare.

But it does show why having international standards for such things may
not be the bad idea many think it is.

--
*If a turtle doesn't have a shell, is he homeless or naked?

Dave Plowman London SW
To e-mail, change noise into sound.

On 09/10/2019 13:44, Dave Plowman (News) wrote:

snip

Wonder if the heat cooked some of the colours? Because I can't see any
reason to start with a 0. Given resistors of less than 1 ohm ain't exactly
rare.

It's 1%, so three bands for the numbers for consistency, I imagine.

Cheers
--
Clive

On Wed, 09 Oct 2019 13:44:30 +0100, Dave Plowman (News) wrote:

OK. Although it would be difficult to measure a fraction of an ohm
accurately anyway.

True, although my bench meter (in 4 wire mode) would do it OK.

Wonder if the heat cooked some of the colours? Because I can't see any
reason to start with a 0. Given resistors of less than 1 ohm ain't
exactly rare.

I agree. 0 at the start is a bit peculiar, although I can't think of any
other interpretation.

--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

In article ,
Clive Arthur wrote:
On 09/10/2019 13:44, Dave Plowman (News) wrote:

snip

Wonder if the heat cooked some of the colours? Because I can't see any
reason to start with a 0. Given resistors of less than 1 ohm ain't
exactly rare.

It's 1%, so three bands for the numbers for consistency, I imagine.

True. Thinking on, many sub ohm resistors are high current so have the
actual value printed on them. At one time.

--
*Nothing is foolproof to a sufficiently talented fool*

Dave Plowman London SW
To e-mail, change noise into sound.