Johan's LA-Light 9v version build report

[Bagge]

I tried a new LDR rated at 20-100k On and 14M Off. Seems like the one MArty used. I still get no effect from Comp knob. MArty did you get any respons from the comp knob before adding the buffer? Howevfe, I think I'm gonna try Flatline comp instead. I just got hold of some CLM6000 vactrols

[Johan]

Bagge.
it says in your earlier post that you used rectangular green LEDs...thosa are usualy not very bright. did you try and change them to regular red LEDs..could be just why it isnt working for you...
johan

[Bagge]

Yes, I did change to red 3 mm LED. And they do respond when playing. I'll do some tweaking with the resistor going to LEDs to make them brighter.

[snaper]

Bump for the re-drawed circuit with the VU

[snaper]

Another question, about the last schemo from Jonah (LA Last one...)
Which LED goes to which LDR? I would like to replace them with Vactrols

[Kipper4]

Here you go took me 3 seconds to find it on google

http://moosapotamus.net/fatNpretty.html

[snaper]

Kmow this, but my question was about the original.
On the final version there are two leds adn two ldrs, one for the limiting, one for the VU meter.

[Johan]

Wow. Has it really been nine years since i uploaded that?...

If using separate leds and ldr, try arrange then so that both leds shine on both ldrs.. Most times it doesn't matter,  but with some ldrs that are slower,  you might get a little distortion on the lowest  frequencys

if you use vtl5c2, it doesn't matter which led goes to wich ldr.
j

[snaper]

Wow. Has it really been nine years since i uploaded that?...

If using separate leds and ldr, try arrange then so that both leds shine on both ldrs.. Most times it doesn't matter,  but with some ldrs that are slower,  you might get a little distortion on the lowest  frequencys

if you use vtl5c2, it doesn't matter which led goes to wich ldr.
j

Yeah, just found it.
I've re-drawed it in eagle. Could you check it?

Dropbox link for PDF version + Eagle SCH :

https://www.dropbox.com/s/v486cvpayyly8ie/LA-Light.pdf?dl=0
https://www.dropbox.com/s/l9ditebgiikhyit/LA-Light.sch?dl=0

[Johan]

The circuit finds/makes its own ground, so you only need a two pole supply,  anywhere from 9 to 30 volt.  That's the opamp with two 10k resistors and output going to ground. So your power input only needs the two outer connections
j

[snaper]

The circuit finds/makes its own ground, so you only need a two pole supply,  anywhere from 9 to 30 volt.  That's the opamp with two 10k resistors and output going to ground. So your power input only needs the two outer connections
j

I see.
But it is not a problem to connect the two grounds together?

[snaper]

Oh, forgot to mention, that I would like to use a +/- 12v psu

[snaper]

Can I just simply omit tha 10ks + opamp section and use the psus gnd?
Would be easier for me :S

[Johan]

Yes, that should work.
J

[snaper]

Thanks Jonah, layout upadted, will etch and build, just ordered the Vactrols from Musikding

[snaper]

Layout done, etched, soldered, everything works fine.
I've replaced the gain reduction pot with a 500k (instead of the 100k), now it can create very very subtle limiting.
VU works fine also, trimmed it 0db, funny that it works "backwards", moves to -, showing the gain reduction.

Used the suggested Vactrols.

Runs from +-12V, will build an FCUK mini power for this, and move it into a 1U case.

Added the limit/comp switch, but there is change, when switching it.
What should it do?

In the other hands, any other mod ideas Jonah?

If you interested, I can post the eagle project files.

[Freppo]

I just remembered that I made a vero layout for this one (Johan's original version)
It was made months ago, but I never built it / verified it, so I forgot about it.

Anyway, here is my layout. It should be ok

Full size version

cheers / Freppo