I'm needing to make some experiences into my standard amplifier, some tweaks, and i have not small values of capacitors, i have only ceramics...and...for this purpose ceramics are not a very good idea.... in special as Miller, or compensation capacitor into the Voltage Amplifier Stage.... so...there are many others i can use made with other dieletric materials to test..but not with the small values i need...from 5 pf to 27pf.
Are there problems to do this?... say, to use them in series to reduce value?... some consequence?... some strange side effect?
Say... some strange inductive, resistive or capacitive effect because size or something?... are there Radio Frequency problems related that stuff.... i remember that series condensers were not used in Radio Frequency transmitters, we use to substitute them for the good value... i can remember that i have used, many times, this series capacitor mid point as an impedance divider....... and the antenna, the aerial, for transmitting pursposes, were soldered into this point.
I am producing question because i really do not know if there are any kind of problems with this.
The question is more directed to scientist alike Roender (Mihai)and others, but forum folks may know something i do not know.
My worries are related to physics...the science that studies the physics of solids.
regards,
Carlos
Are there problems to do this?... say, to use them in series to reduce value?... some consequence?... some strange side effect?
Say... some strange inductive, resistive or capacitive effect because size or something?... are there Radio Frequency problems related that stuff.... i remember that series condensers were not used in Radio Frequency transmitters, we use to substitute them for the good value... i can remember that i have used, many times, this series capacitor mid point as an impedance divider....... and the antenna, the aerial, for transmitting pursposes, were soldered into this point.
I am producing question because i really do not know if there are any kind of problems with this.
The question is more directed to scientist alike Roender (Mihai)and others, but forum folks may know something i do not know.
My worries are related to physics...the science that studies the physics of solids.
regards,
Carlos
Some folks have said the ceramic capacitor react when facing variable levels
...that they are very good into oscilators where you have fixed frequency and fixed level into the carrier....but they change value in accordance to the potencial into the dieletric.
Well.... i have just accepted those informations from forum skilled folks.. but i have never watched that effect behavior..so.. i cannot guarantee nothing.... i am just repeating the same way parrot does.
I have those black dots and red dots too.....i have thousands of nice ceramics units.... and all them tested and guarantee..were used into the past...came from junk...the guaranteed skilled components..were used and passed all tests during operation.
ahahahahahh!
regards,
Carlos
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But dear Mihai...please....answer big fat Charlie question in the place to make another.
...that they are very good into oscilators where you have fixed frequency and fixed level into the carrier....but they change value in accordance to the potencial into the dieletric.
Well.... i have just accepted those informations from forum skilled folks.. but i have never watched that effect behavior..so.. i cannot guarantee nothing.... i am just repeating the same way parrot does.
I have those black dots and red dots too.....i have thousands of nice ceramics units.... and all them tested and guarantee..were used into the past...came from junk...the guaranteed skilled components..were used and passed all tests during operation.
ahahahahahh!
regards,
Carlos
..............................................................
But dear Mihai...please....answer big fat Charlie question in the place to make another.
Dear Carlos,
The NPO ceramic is made from a very stable dielectric material, almost at the same quality level as our beloved silvered mica capacitors.
Now, if you are forced to use a series combination of identically small values capacitors, the only precaution you must take is to use the same voltage tag for both if you use them in VAS as Miller compensation. When you'll get the right value, replace the combined capacitor.
IMHO, the RF effect is to small to mater ...
Cheers,
Mihai
The NPO ceramic is made from a very stable dielectric material, almost at the same quality level as our beloved silvered mica capacitors.
Now, if you are forced to use a series combination of identically small values capacitors, the only precaution you must take is to use the same voltage tag for both if you use them in VAS as Miller compensation. When you'll get the right value, replace the combined capacitor.
IMHO, the RF effect is to small to mater ...
Cheers,
Mihai
i have a circuit i use with my dummy loads to get a 10:1 reduction in voltage going into an o-scope input. i didn't have variable trimmer caps available so i just "kluged" a few 5pf caps together in series and parallel combinations until i got the right compensation for the scope input. works just fine but takes up a bit more space than a trimmer cap.
Thank you Roender...so... i gonna use my ceramics ones
Unclejed and traderbahn
I think this trimmer option is nice too.
thank you folks.
regards,
Carlos
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I have used those twisted wires for low capacitance..they are fine..but you have to fix using something...because if it bent or vibrates or turn near the ground the value will change.
Also air core capacitores have problems with humidity too.
Unclejed and traderbahn
I think this trimmer option is nice too.
thank you folks.
regards,
Carlos
..........................................................
I have used those twisted wires for low capacitance..they are fine..but you have to fix using something...because if it bent or vibrates or turn near the ground the value will change.
Also air core capacitores have problems with humidity too.
I assume you already know about the different dielectric effects on linearity. The better dielectrics come in larger values and sizes. I would say the primary consideration when putting caps in series is the doubled inductance. This may or may not matter in you particular circuit; I'm sure you have thought of this.
BTW, it is possible, if you are cunning as a fox, to combined two caps of different dielectric materials in order to achieve a more linear combination.
BTW, it is possible, if you are cunning as a fox, to combined two caps of different dielectric materials in order to achieve a more linear combination.
Any real capacitor has parasitic inductance and resistance. In simplest form, these appear in series with the cap. So every cap is really a C R L series circuit. If you Google for "capacitor parasitics" you'll find more detailed info.
When you put two identical caps in series you halve the C and double both L and R. When you put two identical caps in parallel, you double the C and halve the L and R.
The R will usually be negligibly small. The L will depend upon the physical size and shape of the cap. There are other parasitics that may be important, especially leakage R in electrolytic caps, but you don't need to worry about this for such small caps. I suppose humidity will introduce a parasitic R in a trimmer in Brazil
A straight bit of thin wire is an inductor and has, very roughly, 5nH/cm. You can estimate the cap inductance from the average length of the signal path through the two caps. Note: inductance is increased much more if the signal path forms a loop: the smaller the loop area, the less L - so how you physically arrange the two caps matters.
Does this make sense?
I am curious as to why you are interested in using such low capacitance values. Transistor junction capacitance is in the region you are interested in and it is extremely non-linear. Valves are a different matter.
Brian
When you put two identical caps in series you halve the C and double both L and R. When you put two identical caps in parallel, you double the C and halve the L and R.
The R will usually be negligibly small. The L will depend upon the physical size and shape of the cap. There are other parasitics that may be important, especially leakage R in electrolytic caps, but you don't need to worry about this for such small caps. I suppose humidity will introduce a parasitic R in a trimmer in Brazil
A straight bit of thin wire is an inductor and has, very roughly, 5nH/cm. You can estimate the cap inductance from the average length of the signal path through the two caps. Note: inductance is increased much more if the signal path forms a loop: the smaller the loop area, the less L - so how you physically arrange the two caps matters.
Does this make sense?
I am curious as to why you are interested in using such low capacitance values. Transistor junction capacitance is in the region you are interested in and it is extremely non-linear. Valves are a different matter.
Brian
Thank you Brian.
I want to have good sinus reproduction into 150 or 200 kilohertz, and this we can achieve only using small capacitors as Miller (compensation)... when we use more traditional values, alike; 47pf, 56pf, 68pf, 82pf, 100pf and above, we have as result the sinus waveform entering the amplifier became a triangle into the output.
Sinus seems to be very well acepted by our ear plus brain...because very natural to electro chemical to reproduce, transmit, or transfer such kind of waveshape to the brain...but triangle will be changed and will look alike a piramid with flat top and rounded corners...much more alike a bad square wave than a triangle.... i want to understand how we perceive this too.... so i need to listen same frequencies and music going to be triangle and to listen the same frequencies and music without this effect.
I want to check some informations i have received that having such kind of frequency response we gonna avoid some phase errors that can be perceived.... i am continuouly checking all informations enters my brain... also i use to test the conclusions i made too... this is my prefered hobby..not to believe unless tested and perceived by me and my close friends.
I have never perceived nothing, as i cannot listen above 14 kilohertz... but some folks said even into 14 kilohertz we will perceive effects (?).
Maybe harmonics.... some people say that we do not listen but we perceive..... seems a little magic to me but makes some sense, as there are other things we do not perceive but produces effects in out brain... even the moon produces effects.
I hope have satisfied your curiosity Brian.
I think thread have informed me all i want to know...if you folks wants to discuss this subject, then go ahead.....i am satisfied and will not feed the thread anymore.... let it rest, as have reached the target... at least mine.
regards,
Carlos
I want to have good sinus reproduction into 150 or 200 kilohertz, and this we can achieve only using small capacitors as Miller (compensation)... when we use more traditional values, alike; 47pf, 56pf, 68pf, 82pf, 100pf and above, we have as result the sinus waveform entering the amplifier became a triangle into the output.
Sinus seems to be very well acepted by our ear plus brain...because very natural to electro chemical to reproduce, transmit, or transfer such kind of waveshape to the brain...but triangle will be changed and will look alike a piramid with flat top and rounded corners...much more alike a bad square wave than a triangle.... i want to understand how we perceive this too.... so i need to listen same frequencies and music going to be triangle and to listen the same frequencies and music without this effect.
I want to check some informations i have received that having such kind of frequency response we gonna avoid some phase errors that can be perceived.... i am continuouly checking all informations enters my brain... also i use to test the conclusions i made too... this is my prefered hobby..not to believe unless tested and perceived by me and my close friends.
I have never perceived nothing, as i cannot listen above 14 kilohertz... but some folks said even into 14 kilohertz we will perceive effects (?).
Maybe harmonics.... some people say that we do not listen but we perceive..... seems a little magic to me but makes some sense, as there are other things we do not perceive but produces effects in out brain... even the moon produces effects.
I hope have satisfied your curiosity Brian.
I think thread have informed me all i want to know...if you folks wants to discuss this subject, then go ahead.....i am satisfied and will not feed the thread anymore.... let it rest, as have reached the target... at least mine.
regards,
Carlos
Doube the Impedance
It is not exactly true that by inserting 2 series caps with 1/2 the desired capacity will doube the capacitive Impedance (Xc) - each cap will have 1/2 the Xc, therefore the total Xc will be 2(Xc + Xc)/2 = Xc.
As for the characteristic or "parasitic" R and L they may be vanishingly small - don't know.
After all, we still have to obey at least the known laws of Physics.
Regards, Grant
It is not exactly true that by inserting 2 series caps with 1/2 the desired capacity will doube the capacitive Impedance (Xc) - each cap will have 1/2 the Xc, therefore the total Xc will be 2(Xc + Xc)/2 = Xc.
As for the characteristic or "parasitic" R and L they may be vanishingly small - don't know.
After all, we still have to obey at least the known laws of Physics.
Regards, Grant
uh, grant..... 1/2 the capacitance doubles Xc. two caps in series halves the capacitance again, so we are now at 1/4 the original capacitance, and have multiplied Xc by 4.
for instance:
at 159 (and some change) Hz
a 1uf cap has an Xc of 1k, so a 0.5uf cap has an Xc of 2k
now put 2 0.5uf caps in series, you get 0.25uf, which has an Xc of 4k
as far as Xc is concerned, it's like putting resistors in series
for instance:
at 159 (and some change) Hz
a 1uf cap has an Xc of 1k, so a 0.5uf cap has an Xc of 2k
now put 2 0.5uf caps in series, you get 0.25uf, which has an Xc of 4k
as far as Xc is concerned, it's like putting resistors in series
unclejed613 said:
Uncle Jed,
thanks for the correction to my algebra - somehow I forgot that dividing the denominator is equivalent to multiplyig the numerator!
Don't know how I deluded myself - been a long time since I have had to deal with this - guess I was thinking in terms of parallel vice series at one point.
regards, Grant
hei uncle charly
i got about 5000 ceramics of diferent values laying arround
( brand new and good quality )
can i sent some over ???? ( i presume that will cost nothing )
let me know
he he my new shop is even closer to the post office !!!!
EDIT ....
i change my mind !!!! i dont give you !!!! i trade them !!!!!! with any brazilian food you can sent with the post !!!!!!! ha ha ha ha ha
i got about 5000 ceramics of diferent values laying arround
( brand new and good quality )
can i sent some over ???? ( i presume that will cost nothing )
let me know
he he my new shop is even closer to the post office !!!!
EDIT ....
i change my mind !!!! i dont give you !!!! i trade them !!!!!! with any brazilian food you can sent with the post !!!!!!! ha ha ha ha ha
Precious parts Sakis..... Brazilian food?... the ones goes walking or the ones
comes into dishes?.... the first one is food to spirit..the other is food to our body?
I will send you this one...she is brazilian... watch the skin colour and you will recognize our people.... but i think Maria will not feel happy with that.
Carlos
comes into dishes?.... the first one is food to spirit..the other is food to our body?
I will send you this one...she is brazilian... watch the skin colour and you will recognize our people.... but i think Maria will not feel happy with that.
Carlos
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traderbam said:
Vacuum is an even better dielectric:
An externally hosted image should be here but it was not working when we last tested it.
traderbam said:
Even I won't drink it, except at baseball (honkbal?) games.
One verbum sapiens if you ever come over stateside -- don't emit any Bud or other "nectar of the hops" onto the streets, sidewalks or darkened corners of Hoboken or Jersey City as the cops find it very irritating ...
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