I normally use the big melf resistors, the are quiet and clear and does not cost an arm or a leg. I rate the way the PCB/housekeeping is made a lot higher than the choice of resistors.
What's the difference between a melf resistor and a normal metal film resistor but with leads welded onto the end caps?
It looks to me like MELF is just the name of the case type, and the rest is just obfuscation to make people think they're some new technology. The benefit is in mechanical rigidity and what's inside depends on what series you buy.
Metal glaze MELF resistors however do have high surge tolerance not unlike carbon composition which is still tougher but prone to moisture and drift.
Metal glaze MELF resistors however do have high surge tolerance not unlike carbon composition which is still tougher but prone to moisture and drift.
There is one metal-metal contact less because there are no wires.
Generally a bigger resistor of the same type has less distortion when the layout is not compromised.
That is beacuse distortion in a resistor ( mostly 3rd harmonic, the Dales are an exception with second dominating ( why ? )) come from thermal modulation.
The noise besides Johnson noise ( that is not reducible ) is the excess noise.
That comes from the granularity of the base material.
Metal Oxyte is worse then Metal Film for example.
I use the Melfs too from a Geraman maker. They have very low excess noise.
Generally a bigger resistor of the same type has less distortion when the layout is not compromised.
That is beacuse distortion in a resistor ( mostly 3rd harmonic, the Dales are an exception with second dominating ( why ? )) come from thermal modulation.
The noise besides Johnson noise ( that is not reducible ) is the excess noise.
That comes from the granularity of the base material.
Metal Oxyte is worse then Metal Film for example.
I use the Melfs too from a Geraman maker. They have very low excess noise.
Am I right that the current noise of the 1k MMB0207 here is -40db?
http://www.mouser.com/ds/2/427/melfprof-239742.pdf
Seems strange considering the lowest number given here is -38db:
Strategies for minimizing resistor-generated noise | EE Times
http://www.mouser.com/ds/2/427/melfprof-239742.pdf
Seems strange considering the lowest number given here is -38db:
Strategies for minimizing resistor-generated noise | EE Times
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Here are detailed measurements :
https://dcc.ligo.org/public/0002/T0900200/001/current_noise.pdf
Unfortunately the colours are a bit hard to decifer.
When i am not blind the big Beyschlag/Vishey melfs i use are very good.
https://dcc.ligo.org/public/0002/T0900200/001/current_noise.pdf
Unfortunately the colours are a bit hard to decifer.
When i am not blind the big Beyschlag/Vishey melfs i use are very good.
When I compare the description of a melf type to a metal film leaded type, I see the same.
I can't see anywhere that explains why melf (metal film on a ceramic substrate) can claim this very high surge current tolerance, when the near identical metal film on a ceramic substrate appears no different.
The lead to cap solder/weld is the weak point. some melfs are cap-less so in essence you solder directly to the resistive element, with only a nickel barrier in between
Metal glaze specifically:
http://www.mouser.com/ds/2/414/hsf-461150.pdf
And even normal MELF resistors are better than chip resistors:
http://new.firstohm.com.tw/MELF.pdf
Like I said, MELF is just the package, what's in it can be carbon film, metal film, high precision, metal glaze etc.
http://www.mouser.com/ds/2/414/hsf-461150.pdf
And even normal MELF resistors are better than chip resistors:
http://new.firstohm.com.tw/MELF.pdf
Like I said, MELF is just the package, what's in it can be carbon film, metal film, high precision, metal glaze etc.
I am referring to the apparent NON difference between a metal film melf and a metal film leaded resistor.
I suspect the difference is between metal film MELF and other SMD resistors.
Any resistor that is built on a bulky Alumina foundation and can absorb heat fast will survive a power surge.
Matal Glaze are the most noise producing of all the metal resistors.
The crimped on, or welded on, lead to end cap does not significantly alter the resistor tolerance to transient surge currents.
who cares about transient surges, melfs are for small signal compact low noise applications. I always use the larger ones, as the have less noise, which just may be of academic nature anyway, but then for phono stages noise paired with overload margin seems to be the ticket for achieving outstanding performance.
Why..?? Small signal class a circuits running very very far from any power limits are non subjects to power-surge. Only place I have issues with resistors are en current feedback Amplifers, and off course in Re in big power amplifiers, for those I prefer metal strip resistors, they are as low in induction as you can get, and have close to zero tempco an great power handling too.
Encapsulating Encapsulating Encapsulating
The most difficult is electrostatic discharge, and cable induction. The airborne emission can become an issue with switching products. What are you aiming at with this question.
Most products are tested according to Low Voltage directive. The primary concern is safety.
The most difficult is electrostatic discharge, and cable induction. The airborne emission can become an issue with switching products. What are you aiming at with this question.
Most products are tested according to Low Voltage directive. The primary concern is safety.