LA2A and T4B

[chriss]

Gary,

it seems to me the LDR & make up amp is the essence of the LA2A

yes that's what I thought and why I thought I could save these two more tubes.
But did I get that right that you as well replaced the el-foil? I understood that this is another essential, since the audio-signal goes to this without being changed in any way, just amplified not even rectified. It's still AC and the EL works more or less like an 'optical loudspeaker' thats brightness depends on a) signal amplitude and b) signal frequency. So I wonder if a LED-circuit leads to the same results as the same thing with EL-foil. But on the other hand, that's what they have done in the LA4A. Did you finish your project with this LED-circuit or was it just tesing things?

Chris

 

[chrissugar]

[quote author="chriss"]So I wonder if a LED-circuit leads to the same results as the same thing with EL-foil. But on the other hand, that's what they have done in the LA4A.
[/quote]

Also Moonlee did the same thing in their EL*P but they used two optocouplers with the LEDs connected antiparalel and the Photo cells paralel.
The only thing that it can't emulate is the time constant 'memory'.

chrissugar

 

[chriss]

Interesting to know chrissugar.

For the two LDR's in parallel: That's what I was asking about in the beginning of this thread but noone answered it. The T4B's in the schematics all show 2 LDR's parallel (except for the one out of te Audio-Cyclopedia). And the two antiparallel LED's: They probably do the rectifiing of the audio-signal, right?

Does anyone know how Tube-Tech does the LDR-driving in the CL1B-compressor?

Any the 'time-constant-memory': Isn't this 'memorized' by the LDR? What you say sounds like you assume the EL-Panel to be the part to memorize. Maybe I'm wrong.

Chris

 

[chrissugar]

chriss

I already wrote about this in another thread:
[quote author="chrissugar"]The sidechain in the EL*P is an ordinary LM386 amplifier circuit that feeds two VTL5C2 conected in antiparallel, one LED for the positive alternance and one for the negative. Also the photoresistors in the attenuator circuit are conected parallel.

chrissugar[/quote]
here is the link:
http://www.groupdiy.com/index.php?topic=6701

 

[gary o]

Hiya Chrissugar, Chriss & anyone else, my understanding in the LA is {correct me if im wrong anyone} yes the time constant memory is the job the cell thats why its so important to get the right one a Silonex NSL5910 I read is the closest these days, and there are ways to test them, the EL panel flashes/shines like an optical speaker at varying brightness nothing to slow it down or to keep it lit for longer.

My LED thing was just for fun I had already built my LA with all tubes but it did work well & its a very basic circuit {il try to find it} theres a little rectifier on board so the LED gets DC, I guess the Moonlee does it a better way ?
As for the 2 cells in parallel id like to no more too, I have tried this .....doesnt seem to make much difference I recorded the exact same audio thru the LA twice ,once with 1 cell then with 2 cells sounded the same but looking at the audio wave form in cakewalk/sonar a couple of the peaks werent quite so peaky on the 2 cell recording, tho I dont no if the 2 cells was the reason could be to do with the cell/s memory, was reading something the other day about priming the LA, iv done this a lot my self just before I sing a loud bit of a song il yell into mike to give the cell bright light & to start the memory, then start recording before it rises right back up it keeps the peaks down.

 

[gary o]

http://www.epanorama.net/counter.php?url=http://www.picks.force9.co.uk/circuits.htm

This should take you to the little LED compressor I just used the LED driver side of the circuit as my side chain.

 

[chrissugar]

Gary O

The Moonlee is smart because it does not rectify the audio signal for the LEDs. The two LEDs beeing conected antiparallel, one will conduct (light up) for the positive alternance of the audio signal and the other for the negative.

chrissugar

 

[gary o]

Yeah I was just workin that out ..thanks of coarse the LEDs are diodes anyway its even simpler & I suppose faster than the bridge rectifier, I might see if I can get this circuit to work this way for experiment.
Also just read a little bit about the elop thing the blurb said the LA2A used a SLOWER EL panel so is there a attack/rise time for the ELs and the LED then?? & would the LED be faster???.
Ive got a sawn in half vactrol in my LA at the moment, maybe shouldnt have sawn it in half haha.

 

[chriss]

Hi guys,

I was just comparing the datasheets of CL5M5L and the Silonex (NSL5910 ist mentioned here, so i refer to 5912):

The R at 2ftc. is 1,5k with both untis.
The min. R at darkness after 5 sec. of 2ftc. is 100k in both units.
Max. Voltage is 170V for both.
Spectral peak is at 550 nm for NSL... and 5500 Angstrom for CL5... (Is 10 Angstroms = 1 nm? Shit! Now have to deal optical formulas as well?!....)
And the material is CdS (whatever..) in both.

So there seems to be no real difference, right? NSL5910, as I said before seems out of production or whatever. But NSL-5912 seem to be the choice.

Any source in Germany or Rest-Europe? Btw. CL5M5L seems still available in the U.S.: http://www.electronicsurplus.com/commerce/catalog/product.jsp?product_id=78349&czuid=1113586462996

Chris

 

[chriss]

Ahhh!

CdS = Cadmiumsufid (Cadmiumsulfide in english??)

May a good DIY-project for the chemical-DIY-fraction :thumb:

Chris

 

[CJ]

Try different cells. NSL has bucket loads of different cells.

Experiment. Be creative. Be the nexy DIY hero! :razz:

Just don't turn into a Steve Jobs.

 

[chriss]

Nor into a Uli Behringer - sorry BehrINGer as hes uses to point out (ING. = german for engineer...)

 

[gary o]

Good point CJ in my personel quest too get close to the real LA sound ive found some other sounds along the way.

But am I right in saying {CJ will prob no this} that if you get hold of a CL5M5L or NSL5910/2 off the shelf it STILL prob wouldnt be to the right spec for real LA, im not saying it wouldnt be any use tho.
So far my favorite sounding cells for vocals anyway is the cell half of Silonex NSL32 & vactec VTL5C4 I think the specs are same as the NSL5910 & so on.

Cheers................. Gary O

 

[chriss]

Well, now I have a working EL-panel-driver on my workbench. It's the circuit from the LA3A followed by a 100V-speaker-transfomer.
It just lacks of a few problems: The output-singal looks distorted on my Osci. And when I touch the output-transistors, they also seem to heat up differently: The 2N4037 (I took an BC141) becomes much hotter than the 2N3053 (BC161 in my case. That should not be, I guess?!.
Since I don't know the voltages this circuit receives in the LA3A, I gave 15 Volts to the first stage and 24V to the output-stage. Can anyone tell, does one of these seem to high or too low?
Ah and I left out the Stereo-adj.-pot. Just have the 1k8 R in there, should I take a higher value here?
And I didn't put an Input-Attentuator in, but I can regulate this on my frequency-generator.

Help!

Chris

 

[chriss]

O.K., O.K., I can talk to myself... No problem....

I found out the problem was my famous 'cold-solder-technique'. Now the thing amplifies and when I give 15V to the first and 30 V to the second stage the symmetry of the signal looks o.k. still not perfect but I think enough to drive an EL-panel...
Now since this worked and the transistors still became quite hot I tried to wire the way I mentioned before: leave the secondary side away and connect GND to 5W, the output (C9 in LA3) to 2,5W and the EL+ to 0,625W (my transformer does not have 0,31 like in the schematics. And hey: It works! Very strange but works.
The higher the frequency rises the more the green turns into blue. Is this normal? Do other T4's behave the same way or am I about to kill my EL? It's very few light at low frequency too.
I think I will measure the output-voltages later.

Chris

Btw.: The transformer I use is this one: (If anyone is interested...)

tr.

They have a very funny datasheet too!

 

[CJ]

Dang, is there any way you can fix the link so my
screen doesen't have to scroll over to New York City?

 

[chriss]

Oh, I'm sorry, just drag&dropped it without looking.

But that's the right time to buy a bigger monitor, CJ, isn't it?...

Chris

 

[CJ]

Point mouse on URL tag to get text instruction.
[url= blah blah blah

 

[chriss]

Ahh, I see, sorry I missed that before, so now again:

transformer

Hmm, but I think the only one the change the long version is the webmaster, right? I'm ashamed.

Chris

 

[chriss]

OHHH NOOO!

Now it doesn't work.... maybe this one:

transformer

Chris