What is the composition/nature of those resistors ?

frank_p · October 21, 2008, 12:27:24 PM

After seeing this topic:
http://www.diystompboxes.com/smfforum/index.php?topic=71510.msg577206#msg577206
I got out some R from the drawer... And, for most of them, I can't tell if they are metal film resistors:
(And I think I had maybe responded too fast about the green Rs)

Dragonfly · October 21, 2008, 03:16:00 PM

They all look to be metal film from various manufacturers (Dale, Vishay, etc) except for #2 and #23 with are carbon film.

I have representatives from "most, if not all" of those various types

frank_p · October 21, 2008, 03:36:30 PM

Quote from: Dragonfly on October 21, 2008, 03:16:00 PM
They all look to be metal film from various manufacturers (Dale, Vishay, etc) except for #2 and #23 with are carbon film.

I have representatives from "most, if not all" of those various types

Thanks a lot Andrew.

Note that a little metal flange is perceptible at the end/lead of number # 2
while number #23 looks like an ordinary carbon film one.

Thanks again !

frank_p · October 22, 2008, 04:21:40 AM

Replies to others who have questions (not meaning arguing about Dragonfly's couselling) (but others who have other advices) ...
Please give advices... (Well, if you want to).

Dai H. · October 22, 2008, 04:51:34 AM

(from your other related thread)

Quote from: frank_p on October 22, 2008, 04:00:38 AM
Quote from: Dai H. on October 22, 2008, 02:55:20 AM
I've seen (and have) carbon film, comp, and metal film in various colours incl. blue, green, red, pink, white, black. Doesn't seem to be any special significance.

So the question is (then) ( and perhaps still is) (Or was) (Or damn, I don't know anymore !!!). How can you identify the natures/composition of resistances based on their apparency. Form ? Lead ends ? Colour bands ? Etc. It seems that there are no clear answer to that (Other than package identification by the manufacturer) (?). Do you have to test them in a noise identifying machine !!!

I can't believe that if someone want to build a Rangemaster with metal film resistors from surplus stores, that it can be such a headache !!!

I may be wrong but, ($%&*!) we are talking about a one stage gain effect with a germanium and some resistors and there are no ways to do it correctly with low costs (surplus) parts without asking to a "certified" trader what is the label (and he could tell you anything ...) of the minimal costing device.

I've went to some stores, and all of them could not tell if their "other than tan colour resistors" were "other than carbon films". And this was to verify some questions about those "green" resistors that some have posted (questions) in this forum, and in my case was to build a Rangemaster for a band that are real friends of mine that want one (rangemaster).

Once I had a fixation on caps appearance. I toughed it was worthwhile. But now we are talking about some resistances... OK, yes they are as important as caps in any audio circuits. But ... .... .... we are talking about some Rs after all.

F.H.P.

Again... Sorry... for the argumentative tone of my post.

so the main question is how can you tell? well, it would seem to me that the existence of a 5th band can be used as an indicator of a metal film in general since typically the tolerance of metal films is 1% or better and for carbon film there is usually only four bands, and the typical tolerance band I've seen on carbon film is 5%; on some old ones 10%, very occasionally 2%. Assuming that it's easier or more worthwhile to make metal film in closer tolerances, or maybe that a tight tolerance for carbon films is perhaps less meaningful because they aren't as stable over temperatures, and also that because metal films can be made to tighter tolerances and it makes sense (because they are more stable)--that would seem to point to a lesser likelihood of differentiation for carbon film and more for metal film (they are more able to be given more exacting values such as 68.1kohms+-1%, 64.9ohms, etc.) thus more likelihood for 5th band generally pointing to metal film. Parts ID can be tricky though since there can be others which seem similar but aren't. Metal glazed might be an example(?--not 100%sure). I have some white 22Meg which sort of look like carbon comp but I'm not exactly sure (had metal on the ends if memory serves, four bands). Some ceramics can look like resistors as well as some inductors because they use the same color band scheme. I have some .25% tolerance resistors (maybe metal foil) which might be confused as caps if they didn't have markings.

frank_p · October 22, 2008, 03:27:20 PM

From now on, I will go with that Dai. Since it make sense and it goes in the same way that Dragonfly have pointed. Yesterday I was discouraged, I've talked to an electronic seller and did not know what was a metal film resistor. He was saying: "What, wire resistors ?" (because film is film in french too, and wire is fil in french...) . He looked confused and just went outside the store because I waited too long to talk to the employee and then got no response.

kierc · October 22, 2008, 04:02:03 PM

No decent input from me, but I just wanted to say I really like the look of #7 and #10 !

How can I get me some of those?

frank_p · October 22, 2008, 06:35:15 PM

They came from a mixed pack of parts from ebay, I think they are Vishay/Dale as Andrew mentionned.
Something like this (but was all mixed, a hell to classify):
http://cgi.ebay.com/NOS-83-PC-VINTAGE-DALE-RLR07C-MIL-RESISTOR-8-4K-1-4W-1_W0QQitemZ120109491047QQcmdZViewItem?_trksid=p3286.m20.l1116#ebayphotohosting

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What is the composition/nature of those resistors ?