SS vs Tubes

[rascal101]

I was talking about the miller capacitance in MOSFETs and the PN junction capacitance in bipolars. That is why you have the cascode to reduce this capacitance.

About the linearity theory ewan ko kay SB.

[tony]

I'm performing bench testing (using an oscilloscope and a signal generator) and I'm running out of ideas how to reduce current spikes in capacitors. Am trying to make a circuit which is a cross between SS and tubes. Similar "slam" as SS and "musicality" of tubes.

you are barking at the wrong tree, this is not as simple as you think. you may use your intruments on better things.

[tony]

I was talking about the miller capacitance in MOSFETs and the PN junction capacitance in bipolars. That is why you have the cascode to reduce this capacitance.

About the linearity theory ewan ko kay SB.

tubes have miller capacitance too, you have the grip plate capacitance, the grid cathode capacitance, by the very physical nature of their construction then add stray capacitance also, so the challenge is to design stages that addresses this issue in order to get good high frequency response.

[rascal101]

@joan2,

Ok transparent and musical from now on.

You know speaker and amplifier designers do not always get together that well ...

I know what you mean and I'm not just referring to the current spikes either.


BTW, I hope I can meet you before you depart for abroad. My friend and I are fans of yours.

Rascal101

[rascal101]

I was talking about the miller capacitance in MOSFETs and the PN junction capacitance in bipolars. That is why you have the cascode to reduce this capacitance.

About the linearity theory ewan ko kay SB.

tubes have miller capacitance too, you have the grip plate capacitance, the grid cathode capacitance, by the very physical nature of their construction then add stray capacitance also, so the challenge is to design stages that addresses this issue in order to get good high frequency response.

Well tubes don't have the problem of driving transformers. You have better inductance vs frequency compared with capacitance vs frequency on the electrolytics.

[tony]

@joan2,

Ok transparent and musical from now on.

You know speaker and amplifier designers do not always get together that well ...

I know what you mean and I'm not just referring to the current spikes either.


BTW, I hope I can meet you before you depart for abroad. My friend and I are fans of yours.

Rascal101

i suggest you visit the links i posted in the "peanuts" thread, lots of things you can learn.

this way you will be able to see thru all the hypes floating around.

[rascal101]

11. The challenge then is how to design an amplifier that is approximates the characteristic of a resistor but can amplify without being capacitive nor inductive.

no, the challenge is how to design a speaker that is purely resistive! this way the job of the amp will be a zillion times easier!
succesfull music reproduction comes when the marriage between the amps and speakers are made in heaven!

case in point, BOSE systems sold together as amps and speakers, who can argue with success?

If only speaker designers can do this. Or if this is achievable.

Buti pa BOSE successful. Kilala pa sa Pinas ng maraming tao.

[tony]

Or if this is achievable

they have been at it for over a hundred years, last time i looked they are still trying

so it really boils down to this, compromises, compromises and still compromises!

[rascal101]

I have been doing bench experiments and just do whatever pops up in my brain. Have been downloading lots of materials about tube and solid state design and am approaching stage by stage. Eg diff input, vas etc. Am trying to verify book vs actuals. Some books kasi don't explain a lot on layout.

[tony]

in order to start leaning about tubes, read the rca tube manual if you can get it. if you understand ss transfer curves, tube curves will be peanuts.

one basic thing you need to understand, bipolar transistors and some type of mosfets are normally off devices, while tubes are normally on devices.

knowing this, right away you will understand that tubes will conduct heavily when grid bias is zero, the opposite of bipolar transistors, zero input bias current means colletor voltage is high, collector current is zero!

[rascal101]

in order to start leaning about tubes, read the rca tube manual if you can get it. if you understand ss transfer curves, tube curves will be peanuts.

one basic thing you need to understand, bipolar transistors and some type of mosfets are normally off devices, while tubes are normally on devices.

knowing this, right away you will understand that tubes will conduct heavily when grid bias is zero, the opposite of bipolar transistors, zero input bias current means colletor voltage is high, collector current is zero!

This is the same principle in SMPS. Presence of gate voltage turns on FET, charge current in transformer however output is zero as switch is on. When gate voltage is low FET is turned off output voltage equals bulk cap voltage / turns ratio. Switch is off.

For flyback, it is when MOSFET is off that energy is transferred to the secondary unlike forward topology which has same waveform as secondary. My question is, for tubes is it a flyback or forward topology?

Also, where can I get an RCA tube manual?

Thanks.

[Jon Agner]

hayyyyy.... feels like 'im in college again siguro kung may internet 20 years ago hindi ako puro 3.0 at 2.75 sa lahat ng electronics subjects ko

[dogears]

I don't think it [Internet] would have made any difference for me Ako lang ang bobo sa electronics sa bahay eh buti na lang marunong akong maghinang
>8O<

[aye]

sir eto ba hanap nyo?

http://www.nmr.mgh.harvard.edu/~reese/RC10/

[Jon Agner]

I don't think it [Internet] would have made any difference for me Ako lang ang bobo sa electronics sa bahay eh buti na lang marunong akong maghinang
>8O<

daw o!!!

[dogears]

[arnoldc]

off topic na kayo. tama na yan.

lahat tayo.

this should be moved to the technical thread.

[dogears]

sorry po
ungano? bakit nga ba andito ito ke sir jadis?

[rascal101]

Ariel,

ty for the link.

Sir joan2,

Binabasa ko na iyung RCA manual.

Sir Arnold, Sir Jadis,

Sorry for the OT.

[tony]

For flyback, it is when MOSFET is off that energy is transferred to the secondary unlike forward topology which has same waveform as secondary. My question is, for tubes is it a flyback or forward topology?

you don't ask questions like these, smps operates in the non-linear region, the switching devices, be they tubes, bipolars, mosfets or igbt's are either on(saturated) or off(cut-off), never in between.

amplifiers operate in the linear region, (ask S_B) of their characteristics curves.
it is a no-no for tubes and transistors to saturate nor be in cutoff, distortion rises abruptly in such cases.