These are still being made, something I only recently discovered. They read just fine to me and I wonder why no discussions ever about ceramic resistors? You'd think the tube folks would be enthusiastic but it's crickets.
Am I missing something? Why AREN'T these good for our purposes? Thanks.
https://www.koaspeer.com/pdfs/HPC.pdf
Am I missing something? Why AREN'T these good for our purposes? Thanks.
https://www.koaspeer.com/pdfs/HPC.pdf
They can be made to tight or loose tolerance. They can be wound in such a way as to be largely non-inductive, if that's an issue.
They are a sub-variety of agglomerated resistors, but the resistive material seems to be metal oxide rather than the more usual carbon.
They have decent characteristics, and importantly they withstand large energy pulses
They have decent characteristics, and importantly they withstand large energy pulses
These are not wirewound, they are some kind of bulk resistance. They seem noninductive by deisgn?
I think these used to be called 'glass resistors'... at least that's the term I recall.
They could be cermet (metallized ceramic) or deposited carbon film resistors. Since no windings are involved in those, inductance would be nanoscopic. Of course, good ol' carbon composition resistors would also just be stuffed, rather than wound as well.
They are made of bulk resistive material. No film or layer involved, meaning no post-manufacturing adjustability but good transient absorption capability and no parasitic inductance
The mention of no parasitic L looked immediately attractive but . . . .
From Ohmite
"Ceramic resistors are commonly used in various kinds of electronic circuits and devices. One very positive nature of Ceramic resistors is high operation temperatures. A drawback of these resistors is that they can create significant amounts of electrical noise. For this reason, a ceramic resistor will seldom be chosen for sensitive radio receivers or other devices which are susceptible to interference."
From Ohmite
"Ceramic resistors are commonly used in various kinds of electronic circuits and devices. One very positive nature of Ceramic resistors is high operation temperatures. A drawback of these resistors is that they can create significant amounts of electrical noise. For this reason, a ceramic resistor will seldom be chosen for sensitive radio receivers or other devices which are susceptible to interference."
So with carbon compositions NLA, this Körting console (had it for years) is rare enough not even a schematic is available, ceramics are not an option, what does one do if non-inductive wire wounds are not available in the needed value?
Looking for 4,7K, 39K, 82K, 180K, 210K, 2,2Meg, all five percents.
My only thought is parallel a resistor of the difference between actual reading and the intended reading, however, this would need continual checking as the carbon composition increases in value. Additionally, the 180K read 2Ω, so this would not be a solution for it.
Looking for 4,7K, 39K, 82K, 180K, 210K, 2,2Meg, all five percents.
My only thought is parallel a resistor of the difference between actual reading and the intended reading, however, this would need continual checking as the carbon composition increases in value. Additionally, the 180K read 2Ω, so this would not be a solution for it.
Digikey lists 108 items for the desired resistance values in Metal Film, Metal Oxide Film, and Thin film with tempco of 50ppm or less.
He can get the three lower resistance values in wirewound there too, but the data sheets for them don't all specify non-inductive.
Without power rating though . . . . .
He can get the three lower resistance values in wirewound there too, but the data sheets for them don't all specify non-inductive.
Without power rating though . . . . .
Because carbon film and metal film are inductive, which is to be avoided in RF circuits.
Even if causes unwanted oscillation in the receiver? 🤔
The vintage consoles and vintage Hammond organs are full of them and contribute to the sound, plus, they work (and sometimes their value does not drift over time, depends on climate and how kept). However, I am not a purist and the ECL86 amplifier section of the console will be getting CMF/CMF Industrial resistors. If I knew with 100 percent certainty would not cause harm, then agree, however, don't have the knowledge or a schematic.
By the way, been unwell since before joining the forum, though given me time to watch a few YouTube videos, including over 250 of Mr. Carlson's, which should be highly recommended for beginners. I know have a lot to learn, but can see have learned a few things and glad didn't get the opportunity to scratch build any device.
The question is, will these cause no harm in the RF?
See, AC and DC are entirely different from RF, but beyond that, I don't know, leave that to the electrical engineers. No schematic to even have somewhere to start research from.
I like Mouser's project lists, I can put a project together (sometimes to kill time while physically unless to do anything) and easily see the cost. Doesn't mean have to use them, but I have (new capacitors in two sets of speakers plus a Heathkit 7A).
You say Körting but not the model.
Have you thought of asking Gorenje for the schematic? If they won't or can't give it to you , there's a good chance you could find one through an EU antique radio enthusiast site. (For example, In a search of "Körting" , the Radiomuseum gives 500 results.)
Have you thought of asking Gorenje for the schematic? If they won't or can't give it to you , there's a good chance you could find one through an EU antique radio enthusiast site. (For example, In a search of "Körting" , the Radiomuseum gives 500 results.)
The question was a general question and desired not to hijack this thread. However, since you have generously asked, will proceed. Interestingly, Körting didn't use models in the expected manner, this example is a 981, though there are a plethora of chassis, my example is a 24651. I have in fact searched, found no results, so deemed rare. She is odd, the only audio valves are ECL86s, what I expect is at least another pre circuit, even a PCB slot for it.
What I find amusing is IIRC my Telefunken is a PP EL84, which has about 1/4 the cabinet size and less speakers, has about four times the wattage output, whereas the Körting is 1/4 the output into more speakers with four times the cabinet size. The Telefunken is like a lady wearing a corset and the Körting a football player wearing a cup. 😆
What I find amusing is IIRC my Telefunken is a PP EL84, which has about 1/4 the cabinet size and less speakers, has about four times the wattage output, whereas the Körting is 1/4 the output into more speakers with four times the cabinet size. The Telefunken is like a lady wearing a corset and the Körting a football player wearing a cup. 😆