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Resistor value
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 |
Resistor value
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 |
Resistor value
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 |
Resistor value
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 -- Ideas are inherently conservative. They yield not to the attack of other ideas but to the massive onslaught of circumstance" - John K Galbraith |
Resistor value
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 |
Resistor value
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 |
Resistor value
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 |
Resistor value
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 |
Resistor value
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 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 |
Resistor value
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.* (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 |
Resistor value
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 |
Resistor value
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. Cheers -- Clive |
Resistor value
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 |
Resistor value
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. SteveW |
Resistor value
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... |
Resistor value
It sounds jolly non standard to me.
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.! "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 |
Resistor value
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 -- ----- -- 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 |
Resistor value
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... |
Resistor value
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 dont 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 doesnt 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 |
Resistor value
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 -- it 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 |
Resistor value
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 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. |
Lonely Psychopathic Senile Ozzie Troll Alert!
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/ |
Resistor value
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 |
Resistor value
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. |
Resistor value
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 |
Resistor value
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 |
Resistor value
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 |
Resistor value
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. |
Resistor value
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 |
Resistor value
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.* (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 |
Resistor value
"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 ? |
Resistor value
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 |
More Heavy Trolling by Senile Nym-Shifting Rodent Speed!
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. Its fecked. Thats 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/ |
Resistor value
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. |
Resistor value
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 :-) |
Resistor value
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. Its 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. |
Resistor value
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 |
Resistor value
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 |
Resistor value
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. |
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