Transistor equivalent

[spec]

Hey JJW (https://www.electro-tech-online.com/members/jjw.200644/) (I can't contact you because you have disabled conversations on your account)

You just voted dislike on my post 417

https://www.electro-tech-online.com/threads/transistor-equivalent.146091/page-21

Can you explain why- I just can't figure it?

spec

 

[spec]

I also ask how to make potentiometer more linear (less logarit)? Linear pot not availabe or to luxury for me. I asked my brother he said add a resistor in parallel with value approx 20% of pot. maxium value but I fell it only more linear a little (I calculated then drew a graph and result this graph only more linear than old graph of pure pot. a little)

Hi Nikolai,

Did you really mean that you can only get log posts- if so that is what you wan't. No need to make linear. That would be the wrong thing to do.

You will need a dual 10K log pot for a volume control on your pre amp, if you make one that is.

 

[spec]

How funny you are! I know if my subwoofer fire to the ground, it can cause an earthquake. Maybe my bad subwoofer has poor sensitivity so it need a lot of power to blow (old subwoofer from junk yard). I ever seen some tube amps with sensitivity speaker play very loud despite output power only 2W.

70W, with loads of output current and little distortion will be loud, loud- did you ask your Dad to strengthen the foundations in your house?

 

[jjw]

Hey JJW (https://www.electro-tech-online.com/members/jjw.200644/) (I can't contact you because you have disabled conversations on your account)

You just voted dislike on my post 417

https://www.electro-tech-online.com/threads/transistor-equivalent.146091/page-21

Can you explain why- I just can't figure it?

spec

Hi
I downloaded the spreadsheet with my tablet, must be misclick, sorry.
I have corrected it now.

 

[spec]

A couple of small projects. Switching PS in an old CD writer is kaput. It's been in the interior of a car for a long time. I found a replacement PS online for like $10.00 USD. Not sure what to look for in a failure. Must have bought them all. That's what happened when I wanted to replace a laptop screen.

Difficult to say, but cracked PCB trace, inductors are favourite, as are the energy transfer caps. The switching tran can also go, but depends on PSU. SMPSs are quite easy to fault find- there is not much to them and all the designs are similar. Often though, the protection circuitry and EMC cloud the issue though. Many SMPSUs will not be happy off-load.

Another general point is the solder joints. They quite often crystallise and go hi resistance where components get hot, and even when not hot. The new earth- hugging solder is particularly bad in that respect. If you can, just reflow the joints using decent old-time solder. Give the board a good clean with IPA first, both sides so you can see what is going on and also clear away any muck which, on rare occasions, can cause leakage around the high impedance control circuitry. I scrub the boards with IPA and a stiff brush- sometimes my toot- brush which gets me into trouble with the missus.

 

[spec]

Hi
Must be misclick, sorry

Thks jjw

spec

(I was thinking of asking fezder to pay you a visit with some of his friends)

 

[Nikolai Petrenko]

70W, with loads of output current and little distortion will be loud, loud- did you ask your Dad to strengthen the foundations in your house?

Not a problem, my foundation was designed can resist a normal earthquake without any damages (the foundation was the part that spend money and time than any other part)

 

[spec]

Not a problem, my foundation was designed can resist a normal earthquake without any damages (the foundation was the part that spend money and time than any other part)

Maybe resist earthquake, but how about Nikolai Petrenko bass sub?

 

[Nikolai Petrenko]

I don't understand, can you ask my again?

 

[Nikolai Petrenko]

Ah, I just understand, you funny!. Bass also OK, can subwoofer make an oscillation like 6 richters earthquake?

 

[Nikolai Petrenko]

New information, >70W subwoofer are available, they diameters are 30cm or approx. 12inches. Price about 350000-450000VND or 16-21USD.

 

[spec]

Nicolai,

There is much to consider about the subwoofer. Can you post a specification. Particularly the resonant frequency, the frequency response curves, and efficiency, or give a link.

(don't be uptight- I am on your side)

PS: How big can the sub cabinet be that will be suitable for your house?

 

[spec]

... Bass also OK, can subwoofer make an oscillation like 6 richters earthquake?

10 Richters

 

[audioguru]

Your photo has a pot marked "B" so it is a linear pot, not an audio volume control that should be marked "A".

 

[Nikolai Petrenko]

Nicolai,

There is much to consider about the subwoofer. Can you post a specification. Particularly the resonant frequency, the frequency response curves, and efficiency, or give a link.

(don't be uptight- I am on your side)

PS: How big can the sub cabinet be that will be suitable for your house?

I posted all information I have received, no more information.
A problem: my hearing too bad I only can hear 20-15700Hz.
I also ask a question: Will magnalium be able to cast heatsink? (or what about magnalium thermal conductivity?) Why I said magnalium, not aluminum? Because I see liquid alum has a high viscosity so it will cause many air bubble or alum won't fill all the mould. Add some magnesium to alum will decrease viscosity of alum. Alloy of alum with magnesi is magnalium. Well?

 

[spec]

I posted all information I have received, no more information.
A problem: my hearing too bad I only can hear 20-15700Hz.

No problem with your hearing at all. That range is excellent.

I also ask a question: Will magnalium be able to cast heatsink? (or what about magnalium thermal conductivity?) Why I said magnalium, not aluminum? Because I see liquid alum has a high viscosity so it will cause many air bubble or alum won't fill all the mould. Add some magnesium to alum will decrease viscosity of alum. Alloy of alum with magnesi is magnalium. Well?

Magnalium would be fine for a heat sink, but no casting is required- see my sketch of case. The back panel is about 3mm, or thicker, aluminium sheet and the heat sink fins are about 2mm thick sheet aluminium bent into a U shape and bolted to the back panel with around 3 mm nuts and bolts. Or, for a neater and better job, you can drill and tap the back panel to bolt the heat sink fins directly into the back panel. The latter approach is recommended.

 

[Nikolai Petrenko]

no aluminum sheet thicker than 2mm, only soda cans and alum door skeletons, some thick alum pieces but too small. I even thaught to do like you approach before because too easy but I realized that thịk alum sheet not available.

 

[KeepItSimpleStupid]

My "take" on frequency response.

See this: https://recordingology.com/in-the-studio/distortion/square-wave-calculations/

Everyone talks about hearing to say 15 kHz and voice is in the neighborhood of 4000 Hz. No one really talks about "impact" or "rise time"

A drum or even a piano has to have an "attack time" , Look at post #1125306 here: https://www.pianoworld.com/forum/ubbthreads.php/topics/1125287/Re:_What_is_"Attack".html

In music, that's what we should care about. A square wave is an infinate combination of odd harmonic sine waves. At 5 harmonics the rise time is starting to look pretty good. I'd love to see those same calculations with rise time computed.

So now, 100 kHz seems very reasonable for audio in the pre-amp stage anyway. A fast rise time amp makes sense to drive the speaker too. I worked on an amp that "choked" when fed a fast rise time signal that the dbx 4bx could produce. It sounded awful.

So, take a cymbal's frequency and multiply it by 5x harmonics. We should really be looking at rise time bandwidth not hearing "bandwidth".

So, you have a :huge" amount of compression and the lack of fast rise time signals in a CD. https://en.wikipedia.org/wiki/Comparison_of_analog_and_digital_recording

Basically, so they can play on wimpy stereo. To play the dynamic range you need a higher power amp.

In conclusion, vinyl sounds better played on a capable system.

 

[KeepItSimpleStupid]

spec:

When referring to posts, you can click on the little number and "Copy Link Location". i.e. post 597 = https://www.electro-tech-online.com/threads/transistor-equivalent.146091/page-30#post-1244315

You can also do it this way:

Post #597

using [url=https://www.electro-tech-online.com/threads/transistor-equivalent.146091/page-30#post-1244315]Post #597[/url]

One thing I hate about BB's is that the links don;t expand on printing. Printed pages are sometimes useless.

 

[Nikolai Petrenko]

Bad news: I was suggested by my friends that don't buy 10000uf caps because many of them are fake. Real capacitance only 2000-3000uf but look very big because caps have a thick layer of bitumen inside. They said me that I should buy 2200-4700uf caps then connect them in parallel (6800-10000uf caps certain good very expensive about over half of price the subwoofer). Well, a "capacitors bird cage" will appear in my amp.