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WTB: carbon comp resistors 1/2watt
Hi, looking for some misc carbon comp resistors in 1/2watt size. Like to
find misc values (e.g. 1meg, 220k, whatever) to keep for my amp/boatanchor projects. if you have any extras laying around whether 20 or 100 or whatever qty let me know at . thanks, dave, n5wnm, okla city, ok -- Posted via Mailgate.ORG Server - http://www.Mailgate.ORG |
http://www.mouser.com/
"David Austerman" wrote in message news:d017f0b4a4c7a5593add915b9f5a986f.32924@mygate .mailgate.org... Hi, looking for some misc carbon comp resistors in 1/2watt size. Like to find misc values (e.g. 1meg, 220k, whatever) to keep for my amp/boatanchor projects. if you have any extras laying around whether 20 or 100 or whatever qty let me know at . thanks, dave, n5wnm, okla city, ok -- Posted via Mailgate.ORG Server - http://www.Mailgate.ORG |
"David Austerman" wrote Hi, looking for some misc carbon comp resistors in 1/2watt size. Like to find misc values (e.g. 1meg, 220k, whatever) to keep for my amp/boatanchor projects. if you have any extras laying around whether 20 or 100 or whatever qty let me know at . thanks, dave, n5wnm, okla city, ok I've been asked to inventory and sell off the ham shack of an SK ham who was also an avid homebrewer. One of the items I noticed in my first visit were two or three Ohmite cabinets with many drawers each of resistors organized in ascending value, starting down around 10 ohms and going up in standard steps up into the megohm range (didn't notice if they are half or quarter-watt). In the few drawers that I opened I didn't notice any vacant compartments. After the holidays (the widow is spending the holidays with out-of-state kids/grandkids) I'll be going back and will photo the stuff and put it on eBay. 73, de Hans, K0HB |
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"John Goller, k9uwa" wrote in message news:MBhtd.151223$V41.46914@attbi_s52... resistors in quantity are maybe 2 cents each. John k9uwa I wish I could find carbon comps (decent values) for two cents each! Those days are long gone around these parts. Pete |
In article ENqtd.176750$cJ3.163057@fed1read06,
PAM says... I wish I could find carbon comps (decent values) for two cents each! Those days are long gone around these parts. Pete www.mouser.com looks like a lot of Carbon Film ones are in the 3 cents each price range to me..... those are 100 lot prices.... so its 3 buks a 100 They are a Dime Each if you wanna onze twoze them ..... so then its 3 buks for 30 of them...... John k9uwa |
I have the following pkgs of resistors, sealed, all allen bradley: 50 per
pack, 5%, $5 per bag 330 ohms, jan rcro7g331js 5 bags $5 per bag 1000 ohms RC07GF102J 3 bags 2200 ohms, JAN RCR07G222JS 3 bags bag with about 25 new resisors of various types, some precision (1%), some carbon up to 1 watt $3 bag of metal film resistors, mostly 1%, some may be better than that, $3 shipping will be no more than $4 now matter what you get, could be less Bill "David Austerman" wrote in message news:d017f0b4a4c7a5593add915b9f5a986f.32924@mygate .mailgate.org... Hi, looking for some misc carbon comp resistors in 1/2watt size. Like to find misc values (e.g. 1meg, 220k, whatever) to keep for my amp/boatanchor projects. if you have any extras laying around whether 20 or 100 or whatever qty let me know at . thanks, dave, n5wnm, okla city, ok -- Posted via Mailgate.ORG Server - http://www.Mailgate.ORG |
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John Goller, k9uwa wrote:
In article Nnutd.176902$cJ3.62398@fed1read06, PAM says... What kind of package? Are they similar to the Allen Bradley cylinder packaging? Or, do they have a more "modern" look to them? I generally look for the NOS Allen Bradley resistors when I can find them. Pete No Pete... they are the newer packaging style... re carbon resistors see comments from the other Bill Turner W6WRT regarding them.... I agree with him.... long term they aren't as stable as the newer metal film resistors John k9uwa How stable do they need to be in an old radio where components values can vary, sometimes by quite a bit, and the radio will still perform just fine? |
"Bill Turner" wrote in message ... On Wed, 08 Dec 2004 10:02:26 -0700, BH wrote: How stable do they need to be in an old radio where components values can vary, sometimes by quite a bit, and the radio will still perform just fine? __________________________________________________ _______ That depends partly on the circuit design and partly on how much any other components in that circuit may have drifted. Without that information, the question can not be answered. -- Bill W6WRT The question is pretty much answered by the fact that most antique radios used 20% carbon resistors. Many of these original resistors have aged upwards of 100% over time, and the radios often still run "just fine". The manufacturers saw no need to use high tolorence components, and most of the circuits are self biasing and self compensating to some degree. Vintage radios aren't rocket science. Good NOS carbon comps from reputable manufacturers are fine. Pete k1zjh |
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"Bill Turner" wrote in message ... On Wed, 8 Dec 2004 16:42:48 -0500, " Uncle Peter" wrote: What you say is true, but still doesn't answer his question. The reason that "The manufacturers saw no need to use high tolerance components" had more to do with cost than careful engineering decisions. I would especially be wary of "NOS" carbon comp. They do NOT get better with age. If you want to use them to maintain the authentic look of an old radio, fine, just be aware that metal film is far superior. When I graduated from high school in 1959 I spent the next few years making a living by repairing those old tube radios and TVs, and a fair amount of the time was spent replacing carbon comps. They were state of the art at the time, but time has marched on. Caveat fixor. -- Bill W6WRT Well, I test every component before I install it, and so far most of the NOS carbon resistors have been well within tolerance. Carbon resistors made much before 1950 do have some issues with aging, and I find 50 to 75% well out of spec and they do get changed. I'd bet most of the resistors you were changing in 1959 are probably the same vintage that are found bad today. I won't argue metal films aren't better, but I haven't had problems with good quality carbons either. Pete |
"Bill Turner" wrote in message ... On Tue, 7 Dec 2004 18:12:35 -0500, " Uncle Peter" wrote: I wish I could find carbon comps (decent values) for two cents each! Those days are long gone around these parts. __________________________________________________ _______ The days of carbon composition resistors are gone for good reason. Unless you are an antique collector and like to restore equipment using original parts, use metal film resistors instead. Their stability and reliability are far superior. -- Bill W6WRT I agree that carbon comp resistors have better alternatives if you are looking for accuracy and stability and low noise. OTOH, carbon comp resistors are an excellent choice for pulse generators and shaping networks. A metal film resistor will exhibit inductance and will often arc across its trim line, usually with catastrophic results. You can hit a 2-watt carbon comp resistor with repetitive pulses of hundreds of watts (peak, keeping the duty cycle low) many times without significant resistance shift and certainly without catastrophic failure. The carbon comps are not the choice for all circuits, but they still have their merits. Ed wb6wsn |
"Ed Price" wrote in message news:mqdud.3291$Af.1453@fed1read07... "Bill Turner" wrote in message ... On Tue, 7 Dec 2004 18:12:35 -0500, " Uncle Peter" wrote: I wish I could find carbon comps (decent values) for two cents each! Those days are long gone around these parts. __________________________________________________ _______ The days of carbon composition resistors are gone for good reason. Unless you are an antique collector and like to restore equipment using original parts, use metal film resistors instead. Their stability and reliability are far superior. -- Bill W6WRT I agree that carbon comp resistors have better alternatives if you are looking for accuracy and stability and low noise. OTOH, carbon comp resistors are an excellent choice for pulse generators and shaping networks. A metal film resistor will exhibit inductance and will often arc across its trim line, usually with catastrophic results. You can hit a 2-watt carbon comp resistor with repetitive pulses of hundreds of watts (peak, keeping the duty cycle low) many times without significant resistance shift and certainly without catastrophic failure. The carbon comps are not the choice for all circuits, but they still have their merits. 1. Something that has to be kept in mind is that most "carbon" resistors being sold today are "carbon film", not "carbon composition" and won't stand repetitive surge pulses. 2. IIRC, a mil-spec "10%" carbon comp can vary 42.4% over its life and still meet spec. Expect commercial parts to be worse. 3. There are ceramic composition resistors available that have all the good properties of carbon comp (except, I'm sure, cost) with none of the bad properties. |
"Ken Finney" wrote in message ... "Ed Price" wrote in message news:mqdud.3291$Af.1453@fed1read07... "Bill Turner" wrote in message ... On Tue, 7 Dec 2004 18:12:35 -0500, " Uncle Peter" wrote: I wish I could find carbon comps (decent values) for two cents each! Those days are long gone around these parts. __________________________________________________ _______ The days of carbon composition resistors are gone for good reason. Unless you are an antique collector and like to restore equipment using original parts, use metal film resistors instead. Their stability and reliability are far superior. -- Bill W6WRT I agree that carbon comp resistors have better alternatives if you are looking for accuracy and stability and low noise. OTOH, carbon comp resistors are an excellent choice for pulse generators and shaping networks. A metal film resistor will exhibit inductance and will often arc across its trim line, usually with catastrophic results. You can hit a 2-watt carbon comp resistor with repetitive pulses of hundreds of watts (peak, keeping the duty cycle low) many times without significant resistance shift and certainly without catastrophic failure. The carbon comps are not the choice for all circuits, but they still have their merits. 1. Something that has to be kept in mind is that most "carbon" resistors being sold today are "carbon film", not "carbon composition" and won't stand repetitive surge pulses. 2. IIRC, a mil-spec "10%" carbon comp can vary 42.4% over its life and still meet spec. Expect commercial parts to be worse. 3. There are ceramic composition resistors available that have all the good properties of carbon comp (except, I'm sure, cost) with none of the bad properties. The ideal resistors for abusive, high-speed transient applications are the silicon carbide (ceramic) resistors (think Carborundum / Cesewid or whatever they call themselves now). But the carbon comp resistors are much cheaper, more versatile (lots more resistance values) and easier to use. I don't know what you mean by the "life" of a carbon comp resistor. My experience is that they last forever, until you kill them somehow. Drift, under low power, hasn't been a problem for me. I have never seen 40% drifts, except for very abused parts, and if you are using the 2-watt carbon comps, you can hear or smell when you are abusing them. The silicon carbide resistors can be pushed so hot that you can use them as room heaters, industrial furnace elements or infrared sources. Oxidation of the plated silver terminals is a small problem. Also, they do have a temperature dependent coefficient of resistance (not as bad as incandescent light bulbs). I agree about the carbon film resistors; they blow up about the same as the metal film resistors. Ed wb6wsn |
Ed Price wrote:
I don't know what you mean by the "life" of a carbon comp resistor. My experience is that they last forever, until you kill them somehow. Drift, under low power, hasn't been a problem for me. I have never seen 40% drifts, except for very abused parts, and if you are using the 2-watt carbon comps, you can hear or smell when you are abusing them. You apparently don't play with many old 30s-40s sets. Finding half the high-value resistors only 200% out of whack would be a good day. -BM |
Bill Turner wrote: On Tue, 7 Dec 2004 18:12:35 -0500, " Uncle Peter" wrote: I wish I could find carbon comps (decent values) for two cents each! Those days are long gone around these parts. __________________________________________________ _______ The days of carbon composition resistors are gone for good reason. Unless you are an antique collector and like to restore equipment using original parts, use metal film resistors instead. Their stability and reliability are far superior. -- Bill W6WRT I see a lot of circuit boards each week thru work and many of them still use carbon comp resistors. I dont think they are near extinction but the demand for them has slowed down quite a bit. I always heard carbon comps were better in radio and audio circuits because of their lack of or very low inductance as opposed to carbon composition which use a spiral of conductive material around a ceramic core which acts as a small inductor......... |
"Bill Turner" wrote in message ... On Fri, 10 Dec 2004 23:19:17 -0800, "Ed Price" wrote: I don't know what you mean by the "life" of a carbon comp resistor. My experience is that they last forever, until you kill them somehow. Drift, under low power, hasn't been a problem for me. I have never seen 40% drifts, except for very abused parts, and if you are using the 2-watt carbon comps, you can hear or smell when you are abusing them. __________________________________________________ _______ Then you just haven't been around long enough. I worked in the TV repair industry for just under 20 years and I have replaced hundreds of carbon comp resistors which were NOT abused in any way, but failed none the less. It's an ancient design which time has passed by. Yup. I just rebuilt an old Heathkit resistor substitution box, 1966 vintage, and the resistors were absolutely wild. Some were better than double the rated value. I don't think I saw any decrease in value. None had any obvious sign of overheating. Having said that, different manufacturers' resistors held up better than others, but today, they are all doubtful. The ABs were good when they were new, the Ohmites were OK, and the IRCs were questionable from the minute they left the factory. |
"Bill Turner" wrote in message ... On Fri, 10 Dec 2004 23:19:17 -0800, "Ed Price" wrote: I don't know what you mean by the "life" of a carbon comp resistor. My experience is that they last forever, until you kill them somehow. Drift, under low power, hasn't been a problem for me. I have never seen 40% drifts, except for very abused parts, and if you are using the 2-watt carbon comps, you can hear or smell when you are abusing them. __________________________________________________ _______ Then you just haven't been around long enough. I worked in the TV repair industry for just under 20 years and I have replaced hundreds of carbon comp resistors which were NOT abused in any way, but failed none the less. It's an ancient design which time has passed by. -- Bill W6WRT I didn't know anybody repairs TV's anymore! g If you had read my entire post, you would have noticed that I wasn't endorsing carbon comps for every resistor design. Consumer electronics is better served by metal film discretes or SMT bricks. I was addressing the sweeping condemnation of carbon comps (I suppose from consumer techs with limited exposure). I suppose you might have noticed when I was talking about my using 2-watt carbon comps in pulse generators and dummy loads; you don't see much of that inside a TV. Just as IC's haven't replaced tubes in EVERY application, carbon comp resistors still are the best solution in a few instances, and I hope the technology isn't completely abandoned. Ed wb6wsn |
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