A better formula for Silonex LDR's

jackinnj · 5th November 2010, 05:29 PM

I plugged in about 100 data points for Current (x) and ON-Resistance (y) for the Silonex NSL32SR3 Attenuator -- the errors for the very low currents are close to zero --

This is much better than the results using the Silonex equations.

Here's the equation - ymmv:

AndrewT · 5th November 2010, 05:46 PM

Can I assume that e5 = 10^5?

kristleifur · 5th November 2010, 05:48 PM

Quote:

Originally Posted by AndrewT

Can I assume that e5 = 10^5?

Yep, that is the notational custom - as I know it at least

jackinnj · 5th November 2010, 05:55 PM

I liked it because there is no exponentiation, and only a few terms. The equations with multiple terms offer no improvement in accuracy. A stepwise approximation can probably resolve the low ohms error.

udailey · 5th November 2010, 06:38 PM

How many different LDRs is this based on John? One with 100 measurements or several with several measurements? Yeah, their datasheet is nothing close to real use.
Uriah

Blues · 5th November 2010, 08:07 PM

Nice one Jack...btw, x=current in uA. Actual testing/matching is still the way to go but it can serve as cross reference.

Blues · 5th November 2010, 08:17 PM

On second thought...your formula is pegged down at 47R...it certainly can go lower

jackinnj · 8th November 2010, 01:03 AM

Quote:

Originally Posted by Blues

On second thought...your formula is pegged down at 47R...it certainly can go lower

the very low resistance points are the insertion loss.

do the math for a 0.5dB 100K+100K attenuator -- you need accuracy in the tens of picoamps in the part of the range where we do most of our listening.

Blues · 8th November 2010, 05:08 AM

Quote:

Originally Posted by Blues

On second thought...your formula is pegged down at 47R...it certainly can go lower

And can also go much higher, I might add, and controllable too.

Quote:

Originally Posted by jackinnj

the very low resistance points are the insertion loss.

do the math for a 0.5dB 100K+100K attenuator -- you need accuracy in the tens of picoamps in the part of the range where we do most of our listening.

Not quite...with a more precise power delivery "engine"

. Listening range is mostly in 10s of uA to 100s of uA. With this design working range is from <1uA thru 10s of mA.

I'll probably start a thread...

jackinnj · 12th November 2010, 03:19 PM

Several forms of equations will work -- but I have to say that the Silonex devices are all over the place!

Here's my setup -- using an LTC or ADI difference amp allows stable current in the picoAmperes:

5th November 2010, 05:29 PM	#1
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	A better formula for Silonex LDR's I plugged in about 100 data points for Current (x) and ON-Resistance (y) for the Silonex NSL32SR3 Attenuator -- the errors for the very low currents are close to zero -- This is much better than the results using the Silonex equations. Here's the equation - ymmv:

5th November 2010, 06:38 PM	#5
udailey Passive Aggressive diyAudio Member Join Date: Mar 2008	How many different LDRs is this based on John? One with 100 measurements or several with several measurements? Yeah, their datasheet is nothing close to real use. Uriah __________________ You can purchase LDRs anytime to build a standard LDR attenuator or to build my new LDR Attenuator "A Lighter Note". Email me. diyldr@gmail.com

5th November 2010, 08:07 PM	#6
Blues Lightning In A Bottle diyAudio Member Join Date: Sep 2003 Location: The Milky Way	Nice one Jack...btw, x=current in uA. Actual testing/matching is still the way to go but it can serve as cross reference. __________________ Leap into the Warpspeed wormhole... http://www.6moons.com/audioreviews/warpspeed/1.html

5th November 2010, 08:17 PM	#7
Blues Lightning In A Bottle diyAudio Member Join Date: Sep 2003 Location: The Milky Way	On second thought...your formula is pegged down at 47R...it certainly can go lower __________________ Leap into the Warpspeed wormhole... http://www.6moons.com/audioreviews/warpspeed/1.html

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5th November 2010, 05:46 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Can I assume that e5 = 10^5?

5th November 2010, 05:55 PM	#4
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	I liked it because there is no exponentiation, and only a few terms. The equations with multiple terms offer no improvement in accuracy. A stepwise approximation can probably resolve the low ohms error.

12th November 2010, 03:19 PM	#10
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Several forms of equations will work -- but I have to say that the Silonex devices are all over the place! Here's my setup -- using an LTC or ADI difference amp allows stable current in the picoAmperes:

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