"What" compressor silly Qs

[Aharon]

Finally it seems I got a project past the planning stage.
I'm almost ready to populate the PCB,just a few parts more and a few questions.Some may seem obvious but bear in mind I'm a neebie.
The elements labeled LK1 to 4 are links(or jumpers)right?.
I don't see a pad for the stereo sw(S3),just add one?
I'm going to use the generic PS for the Calrec,is that ok?
For the allignement,remove the link and measure resistance on the VTL5C9 and at the same time set the trim for 50K,I'm asssuming the resistance on the VTL will change when I turn the trim,is that correct?.
Went to buy yellow LEDs and there's different MDC values,some 80 some 50,which one should I buy,clear yellow 80MDC OK?.
I'm using the TL074 version.
Thanks in advance for any help
Aharon

 

[Aharon]

Here's a link
http://dt.prohosting.com/hacks/what.html
Aharon

 

[Svart]

did you use a board layout availiable on the internet?
the higher the MCD the brighter the LED. , clearer the lens on the led usually the brighter too, plus it won't glow, but will rather act like a flashlight and output a nice beam and spot!

 

[Aharon]

Thanks for pitching in svart.
Yes,I used this layout available here:

http://1176neve.tripod.com/1176/id5.html

further help appreciated.
Thanks
Aharon

 

[peterc]

Hi Aharon

The elements labeled LK1 to 4 are links(or jumpers)right?.

They were put in to make the PCB design easier.

I don't see a pad for the stereo sw(S3),just add one?

Yes, add it in as you see fit.

I'm going to use the generic PS for the Calrec,is that ok?

Any decent +15v, 0v, -15v supply will work.

asssuming the resistance on the VTL will change when I turn the trim

Set the resistance of the resistor in the VTL for 50k, not the trimpot.

different MDC values,some 80 some 50,which one should I buy,clear yellow 80MDC OK

Setting the trimpot should compensate for the different intensities.

Peter

 

[Aharon]

asssuming the resistance on the VTL will change when I turn the trim

"Set the resistance of the resistor in the VTL for 50k, not the trimpot."
peterc



Thanks peterc for all that help.
Ah!!,never worked with the VTL,I didn't know the resistor was variable,that's one of the parts still in the mail so I haven't even seen it yet.
Thanks
Aharon

 

[Aharon]

"Thanks peterc for all that help.
Ah!!,never worked with the VTL,I didn't know the resistor was variable,that's one of the parts still in the mail so I haven't even seen it yet.
Thanks
Aharon "


Ok now I feel like a goof,I just gor the package and of course I'm looking for the trim screw in the VTL,ha!.
Ok can you tell me peterc (or anybody)which resistors I have to change to adjust the VTL's resistance?.
Thanks a million
Aharon(total solid state newbie)

http://dt.prohosting.com/hacks/what1.gif


The notes say set the trimpot for 50K:

"Once the circuit is built up, apply 20VAC and quickly check the +/- 15
volt supplies, feeling for any heat on the regulators or other chips.
If all is well, remove JP1 and JP2. For each channel, measure the
resistance across the photoresistor and set the trim pot for 50K
ohms. Then reinstall the jumpers."

For the life of me I can't see a trim for the VTL.Please help!.

http://1176neve.tripod.com/1176/id5.html

 

[ChumpitO]

Trim goes under R12 on the far right, correct?
I think what he means is to measure the resistor side of the Vactrol and use the trim pot to make that 50k :? .
AFWIW, the VTL is just like a diode placed next to a LDR encapsulated. So when as you change the brightness of the LED you change the resistance.

 

[Aharon]

Thanks Chumpito,I will get it eventually.Yes,I see the 50K trim,and that trim controls the bias or brightness of the led in the VTL.
I will measure while trimming.Got it(I think).
I really appreciate the patience you have
Aharon

 

[ChumpitO]

Good to ask questions as I am planning on building a couple myself and trying to get things sorted also. :wink:

 

[StephenGiles]

I did some recording with my wife on Sunday, she was singing and I road (well, living room) tested my dual What Compressor on her voice. The result was a nice thick vocal sound. She has a high voice, prone to throw the meters well into the red on some notes, so the What evened it out very well. I changed one resistor in order to increase the maximum compression from "some" to "a lot". I also used NSL 32 optos, which meant changing the series resistor from 1k to 33R!
Stephen

 

[Aharon]

Hey Stephen,glad it worked out for you.
That opto sub is an interesting one since I can get it locally unlike the VTL.
I'll try that,you are refereing to the 1k comming from the transistor to the LED in the opto right(R41/65)?

Now that I'm very close to populating I find some of the resistor values whimsical(I'm sure there was a reason) but would I screw up if instead of 5.49k I used a 5.5k?.
Thanks fo any info/help
Aharon

 

[rafafredd]

[quote author="StephenGiles"]I changed one resistor in order to increase the maximum compression from "some" to "a lot". [/quote]

WICH resistor?

 

[StephenGiles]

R18 - 10k on the circuit is 47k on mine. What you could also do is use a 10k fixed resistor and a 47k linear pot so that you can set the maximum compression.
Stephen

 

[omeiko]

Hello.

I'm interested in this circuit too but it's wery hard to get VTL's here in Finland.

I can get silonex optos from farnell but what are the things to consider when subbing a optocoupler?
Could I make this circuit work for example with this? http://www.farnell.com/datasheets/1160.pdf

Thanks

-Okko

 

[Michael Krusch]

If you compare the specs:
VTL5C9: 630Ohm
NSL37-V51: 30kOhm
NSL32 :500Ohm (but at higher current)

Attack time:
VTL5C9: 4ms
NSL37-V51: 2,5ms
NSL32 : 3,5ms

Release Time:
VTL5C9: 50ms
NSL37-V51: 35ms
NSL32 : 500ms

The NSL37-V51 has a different On Resistance, so you have to change the voltage devider. On the other hand the NSL32 looks closer, but with a very long release time.
Get both Silonex and make a test, maybe you like the long release time. I have used a VTL5C4/2 in my LA-4A clone. It has 1,5s release time, but it's not that slow. So I would go for the NSL-32.

Or you can contact one of their distributors http://optoelectronics.perkinelmer.com/content/corporate/europe.html and ask for a sample.

 

[Aharon]

Well,the power supply is up and running,few more parts and I may have lift off.
Aharon

 

[tk@halmi]

[quote author="Michael Krusch"] On the other hand the NSL32 looks closer, but with a very long release time.
[/quote]

The part NSL-32SR3 (different from plain NSL-32) has a very short release time as well. It is nearly the quickest opto on the market.

Tamas

 

[omeiko]

Hi Michael.

Do you mean the voltage divider formed by r25 and the opto-cell? (the schematic is here http://dt.prohosting.com/hacks/what1.gif )

Should I change the r25 to say 30kOhm to match the resistance of the NSL37-V51?
Sorry for my ignorance but I haven't worked with optos before.

Farnell doesn't carry NSL-32SR3 any more :sad: so I'll have to use either NSL37-V51 or NSL32. They still had it in stock about a week ago but not anymore.

cheers

-Okko

 

[Michael Krusch]

Yes, R25 is the one to change. 681 Ohm seams to fit the on resistance of his opto. Send 20 mA through the LED of your opto an messure the resistance and match R25 to it. On resistance can vary with every piece.

But try to get a Vactrol sample. I've got two Vactrols as a sample from the german department. But don't say you only need this two ones, tell of a few hundred, but you are still in the development stage. :grin: