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Old 27th May 2008, 03:34 PM   #1361
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While I was at it, here is a version for two channels worth of LDRs.

R3 and R4 assume higher values, but I'll leave you to figure that
out experimentally.
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File Type: jpg atten sch 2.jpg (41.1 KB, 3972 views)
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Old 27th May 2008, 05:11 PM   #1362
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OK, this would be the last manual version that you are
likely to see. It has all the pieces, and allows pretty complete
adjustment of input impedance and range, top to bottom.

As a 2 channel piece, LDR1 and LDR3 should be matched to
each other, and LDR2 and LDR4 should also be matched.
The match should take place around the 5 Kohm resistance
value. LDR1 and 3 do not have to match LDR2 and 4.
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Old 27th May 2008, 05:13 PM   #1363
john65b is offline john65b  United States
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If this sounds anywhere as nice as the Lightspeed in front of your JFET BOZ, I will build and like it.
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File Type: png n-pass_2sk170-boz_1.png (8.0 KB, 3725 views)
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Old 27th May 2008, 06:37 PM   #1364
Tolu is offline Tolu  Germany
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I thing this Lightspeed version has too less attenuation (-40dB) when you put the powerful JFETBOZ (+22 dB) behind it!
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Old 27th May 2008, 06:45 PM   #1365
Blues is offline Blues  United States
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Default Stereo LDR Circuit with Buffers

Quote:
Originally posted by Nelson Pass
OK, this would be the last manual version that you are
likely to see. It has all the pieces, and allows pretty complete
adjustment of input impedance and range, top to bottom.

As a 2 channel piece, LDR1 and LDR3 should be matched to
each other, and LDR2 and LDR4 should also be matched.
The match should take place around the 5 Kohm resistance
value. LDR1 and 3 do not have to match LDR2 and 4.
As posted by Mr. Pass here's the stereo circuit in detail. Let me know if I missed something...
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File Type: zip stereo ldr circuit with buffers by nelson pass.zip (7.6 KB, 958 views)
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Old 27th May 2008, 07:23 PM   #1366
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Quote:
Originally posted by Tolu
I thing this Lightspeed version has too less attenuation (-40dB) when you put the powerful JFETBOZ (+22 dB) behind it!
I deliberately chose -40 dB because the tracking was still pretty
good. In the lastest version, you can adjust the range pots to
get down to -70 or -80 dB if you want.

And of course you can have less gain in the JFETBOZ without
any difficulty.
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Old 31st May 2008, 09:35 AM   #1367
Harry3 is offline Harry3  Australia
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As there are a number of TL431 types available, what is the prefered version?
Thanks
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Old 31st May 2008, 03:46 PM   #1368
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Default jboz buffer

Nelson,

Newbie question.........

What if I don't want any gain from the jboz. I just want the connection as follow:

" CD - Lightspeed with buffer - poweramp with 12k input."

I thought I'll need a buffer with 600R to 1K output, am I right?

Many thanks

Albert
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Old 31st May 2008, 03:51 PM   #1369
AndrewT is offline AndrewT  Scotland
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Hi,
your proposed buffer could have an output impedance of around 1ohm.
Just add a series resistor to make it tolerant of shorting the output.
100r would usually do.
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Old 31st May 2008, 03:54 PM   #1370
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Andrew,

Thanks for the reply,

I mean 600R to 1K, or anything lower than 600R.

Albert
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