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Value drift over time
Before I junked that RF sig gen I snipped a selection of resistors out of
it just to see how far away from their nominal values they have strayed over the past ~65 years. I shall report back in due course.... -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
Value drift over time
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Value drift over time
On Friday, 17 May 2019 21:19:11 UTC+1, Mike Coon wrote:
In article , says... Before I junked that RF sig gen I snipped a selection of resistors out of it just to see how far away from their nominal values they have strayed over the past ~65 years. I shall report back in due course.... I can hardly wait! I must have some dating back to before when I was 10 y.o too ;-) Mike. I have a few from the 1920s. Don't look a lot like modern Rs. Not sealed either. NT |
Value drift over time
On Fri, 17 May 2019 21:19:07 +0100, Mike Coon wrote:
I can hardly wait! Then I shall keep you in suspense no longer. Here's what I found from a random selection of old components I snipped out. Firstly, pretty much *all* the capacitors were fine. The 350VDC Hunts capacitors could easily have been new. An Erie plate ceramic of 0.01uF likewise. A Dubilier type SM22 50pf cap, however, had gone up to 62pF. That one was one of the ones used for tuning. The biggest changes were as expected in the carbon resistors, all of which aged to higher values like so: 27k became 38.6k another 27k ---- 29k 100k ---- 107k 10 ---- 10.7 3.3k ---- 4.2k 4.1k ---- 5.2k 15k ---- 20.7k 220k ---- 246k 8.2k ---- 9.9k 400k ---- 509k These were all marked with a silver tolerance band, so clearly Taylor back then at least not *that* bothered about accuracy. -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
Value drift over time
On Sat, 18 May 2019 15:22:29 +0000, Cursitor Doom wrote:
The 350VDC Hunts capacitors could easily have been new. Same type as this: https://tinyurl.com/y6a9ywtz -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
Value drift over time
On Saturday, 18 May 2019 16:22:32 UTC+1, Cursitor Doom wrote:
On Fri, 17 May 2019 21:19:07 +0100, Mike Coon wrote: I can hardly wait! Then I shall keep you in suspense no longer. Here's what I found from a random selection of old components I snipped out. Firstly, pretty much *all* the capacitors were fine. The 350VDC Hunts capacitors could easily have been new. An Erie plate ceramic of 0.01uF likewise. A Dubilier type SM22 50pf cap, however, had gone up to 62pF. That one was one of the ones used for tuning. The biggest changes were as expected in the carbon resistors, all of which aged to higher values like so: 27k became 38.6k another 27k ---- 29k 100k ---- 107k 10 ---- 10.7 3.3k ---- 4.2k 4.1k ---- 5.2k 15k ---- 20.7k 220k ---- 246k 8.2k ---- 9.9k 400k ---- 509k These were all marked with a silver tolerance band, so clearly Taylor back then at least not *that* bothered about accuracy. Most Rs in valve kit are far from critical. 5% would have cost them more than 10%. 20% were more common. NT |
Value drift over time
On Sat, 18 May 2019 09:25:35 -0700, tabbypurr wrote:
Most Rs in valve kit are far from critical. 5% would have cost them more than 10%. 20% were more common. I just put it down to post-war lack of availability but your guess is as good as mine. My experience with valves is not that great. I'm really more of the germanium semiconductor era. ;-) -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
Value drift over time
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Value drift over time
I was in the elctronic surplus bisness from the 60's to the end of the
century. Most people thought that Allen-Bradleys were the gold standard. One cusomer complained and we started checking samples. They were all out of tolerance. A-B's speck sheet specified how to measure. For a given resistance range you applied a specified voltage and measured the current. As an aside: In the 50's I ran across some carbon comp. resistors that had been modified. Apparently the person was short of cash or in a hurry. The person took a CC and a triangular file and raised the CC to the value neede. CP |
Value drift over time
On Sat, 18 May 2019 18:20:37 -0700, MOP CAP wrote:
Apparently the person was short of cash or in a hurry. The person took a CC and a triangular file and raised the CC to the value neede. We used to do the same sort of thing with xtals in the days when they were expensive and hard to come by. -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
Value drift over time
On Sunday, 19 May 2019 12:09:10 UTC+1, Cursitor Doom wrote:
On Sat, 18 May 2019 18:20:37 -0700, MOP CAP wrote: Apparently the person was short of cash or in a hurry. The person took a CC and a triangular file and raised the CC to the value neede. We used to do the same sort of thing with xtals in the days when they were expensive and hard to come by. Couldn't do that with my oldest crystal, it's in a valve glass envelope. 5kHz IIRC. NT |
Value drift over time
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Value drift over time
On Sun, 19 May 2019 10:19:17 -0500, Fox's Mercantile wrote:
Except you didn't use a file. You used 600 grit silicon carbide paper and a piece of glass for a flat surface. Yup, the principle is the same, though. For the final fine 'adjustment' we'd use Vim, which is a kitchen scouring powder in the UK and many times less aggressive than 600 grit. -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
Value drift over time
On Saturday, May 18, 2019 at 8:22:32 AM UTC-7, Cursitor Doom wrote:
Here's what I found from a random selection of old components I snipped out. 27k became 38.6k another 27k ---- 29k 100k ---- 107k Good to know, but the aging of composition resistors doesn't tell us much about carbon film resistors (the common low-spec type nowadays) or metal film (the common high-spec type) and manufacturer coatings and such are likely to be changing from year to year as well. Probably, because conductive (metallic or semimetallic) items are positive valence, oxidation will raise resistance with time, for almost anything. How much time, is still a mystery (for almost anything we build today, at any rate). There's too much chemistry involved to make a really good long-life high accuracy projection for most real components. Humidity, ozone, fungus, air pollution... so MANY variables. |
Value drift over time
On Sunday, 19 May 2019 21:12:54 UTC+1, whit3rd wrote:
On Saturday, May 18, 2019 at 8:22:32 AM UTC-7, Cursitor Doom wrote: Here's what I found from a random selection of old components I snipped out. 27k became 38.6k another 27k ---- 29k 100k ---- 107k Good to know, but the aging of composition resistors doesn't tell us much about carbon film resistors (the common low-spec type nowadays) or metal film (the common high-spec type) and manufacturer coatings and such are likely to be changing from year to year as well. Probably, because conductive (metallic or semimetallic) items are positive valence, oxidation will raise resistance with time, for almost anything. How much time, is still a mystery (for almost anything we build today, at any rate). There's too much chemistry involved to make a really good long-life high accuracy projection for most real components. Humidity, ozone, fungus, air pollution... so MANY variables. You can eliminate all those with glass, vacuum & getter. Then you find one day that the getter is oxidised & the bulb contains hydrogen. NT |
Value drift over time
On Sun, 19 May 2019 13:24:18 -0700, tabbypurr wrote:
You can eliminate all those with glass, vacuum & getter. Then you find one day that the getter is oxidised & the bulb contains hydrogen. I was under the impression that glass was impermeable even to omnipresent hydrogen. Or is there a path via where the base pins protrude? -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
Value drift over time
On 5/19/19 5:45 PM, Cursitor Doom wrote:
I was under the impression that glass was impermeable even to omnipresent hydrogen. Or is there a path via where the base pins protrude? Hydrogen atoms are really really small. Trying to keep hydrogen in or out is always problematic. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
Value drift over time
On 20/5/19 10:50 am, Fox's Mercantile wrote:
On 5/19/19 5:45 PM, Cursitor Doom wrote: I was under the impression that glass was impermeable even to omnipresent hydrogen. Or is there a path via where the base pins protrude? Hydrogen atoms are really really small. Trying to keep hydrogen in or out is always problematic. Also, a kilogram of hydrogen at a given pressure takes more space than any other gas. |
Value drift over time
On Sunday, 19 May 2019 23:45:14 UTC+1, Cursitor Doom wrote:
On Sun, 19 May 2019 13:24:18 -0700, tabbypurr wrote: You can eliminate all those with glass, vacuum & getter. Then you find one day that the getter is oxidised & the bulb contains hydrogen. I was under the impression that glass was impermeable even to omnipresent hydrogen. Or is there a path via where the base pins protrude? Glasslinger did a mass spec analysis to discover that gassy valves contain hydrogen. I don't know whether that permeates through the glass (unlikely since most valves stay hard), leaks in through pin sealing defects or is the result of remaining water vapour reacting with the getter. Either way a getter that could capture it would be a good thing probably. https://www.youtube.com/watch?v=16vOoF_XUB8 NT |
Value drift over time
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Value drift over time
On 2019/05/18 11:22 a.m., Cursitor Doom wrote:
On Fri, 17 May 2019 21:19:07 +0100, Mike Coon wrote: I can hardly wait! Then I shall keep you in suspense no longer. Here's what I found from a random selection of old components I snipped out. Firstly, pretty much *all* the capacitors were fine. The 350VDC Hunts capacitors could easily have been new. An Erie plate ceramic of 0.01uF likewise. A Dubilier type SM22 50pf cap, however, had gone up to 62pF. That one was one of the ones used for tuning. The biggest changes were as expected in the carbon resistors, all of which aged to higher values like so: 27k became 38.6k (bad) another 27k ---- 29k (within 10%) 100k ---- 107k (within 10%) 10 ---- 10.7 (ditto) 3.3k ---- 4.2k (bad) 4.1k ---- 5.2k (bad) 15k ---- 20.7k (bad) 220k ---- 246k (barely bad - just above 10%) 8.2k ---- 9.9k (bad) 400k ---- 509k (bad) These were all marked with a silver tolerance band, so clearly Taylor back then at least not *that* bothered about accuracy. No, those resistors have drifted since their original construction. People did have ohm-meters back then and would verify values on resistors particularly if they were colour deficient or colour blind as I did, testing Rs when building kits - red/green deficient vision. I still check almost all resistors I come across with a meter as I don't trust my green, dark red, and brown differentiation. If they are in power circuits - plate or cathode or voltage dropping then those do drift as they were only compressed carbon and heat/cooling cycles would cause them to change value - usually upwards as you have discovered. I consider your values typical of tube gear that is 40 or more years old. 1920s resistors were a chunk of carbon rod with a wire wrapped around each end then dipped in a sealant - how long do you think that value would last within X%? Wire wound resistors external connections were pressure bonded to the resistance wire, not uncommon for that joint to fail over time... Like I said earlier you HAVE to verify all the resistors as they wander over time. Modern Rs are much more reliable when operated under their rated wattage. John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
Value drift over time
On Monday, 20 May 2019 13:40:53 UTC+1, John Robertson wrote:
1920s resistors were a chunk of carbon rod with a wire wrapped around each end then dipped in a sealant - how long do you think that value would last within X%? Wire wound resistors external connections were pressure bonded to the resistance wire, not uncommon for that joint to fail over time... I presume you mean carbon composition rod. Pure carbon would give too few ohms to have much use in a valve radio. Some Rs used metal caps instead of wires, and were mounted in a clip-in holder. I guess they needed to be replaced sometimes as different valves sometimes needed different grid leak values. Like I said earlier you HAVE to verify all the resistors as they wander over time. Modern Rs are much more reliable when operated under their rated wattage. John :-#)# as long as it's well under. Rated life for power Rs operated at specced power can be terrible. NT |
Value drift over time
On Mon, 20 May 2019 08:11:31 +0100, Mike Coon wrote:
In article , says... Hydrogen atoms are really really small. Trying to keep hydrogen in or out is always problematic. In practice you get molecules on the two-fer principle which are much bigger. Helium is bad too because then the atoms come at you singly... May seem counter-intuitive, but hydrogen is not actually the smallest atom. Heliums come singly alright, which is one of the reasons, along with small size, they're used for this kind of leak testing. -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
Value drift over time
On Monday, May 20, 2019 at 3:46:16 PM UTC-7, Cursitor Doom wrote:
On Mon, 20 May 2019 08:11:31 +0100, Mike Coon wrote: In article , says... Hydrogen atoms are really really small. Trying to keep hydrogen in or out is always problematic. In practice you get molecules on the two-fer principle which are much bigger. Helium is bad too because then the atoms come at you singly... May seem counter-intuitive, but hydrogen is not actually the smallest atom. Heliums come singly alright, which is one of the reasons, along with small size, they're used for this kind of leak testing. Good point; also, the H2 molecule has two 1S-like electrons, which is very similar to a Helium atom, and just about as slippery. H2 atoms are lighter than He, on average. |
Value drift over time
On Monday, May 20, 2019 at 3:46:16 PM UTC-7, Cursitor Doom wrote:
On Mon, 20 May 2019 08:11:31 +0100, Mike Coon wrote: In article , says... Hydrogen atoms are really really small. Trying to keep hydrogen in or out is always problematic. In practice you get molecules on the two-fer principle which are much bigger. Helium is bad too because then the atoms come at you singly... May seem counter-intuitive, but hydrogen is not actually the smallest atom. Heliums come singly alright, which is one of the reasons, along with small size, they're used for this kind of leak testing. Good point; also, the H2 molecule has two 1S-like electrons, which is very similar to a Helium atom, and just about as slippery. H2 molecules are lighter than He atoms, on average. |
Value drift over time
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Value drift over time
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Value drift over time
On Tue, 21 May 2019 10:20:02 -0400, Ralph Mowery wrote:
Hydrogen is also explosive or will burn. That is another reason not to just spray it out for leak detection. I think that hydrogen may be the smallest atom, but they often join in pairs to make up a larger molicule. Some other atoms that are normally gas do the same thing. Oh boy. Where do I start? -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
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