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GB: A Simple Discrete Current-Mirror IV Converter, à la AD844

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R

Ripster

Member
Joined 2018
#1
Hi all I am starting GB for a Simple Discrete Current-Mirror IV Converter, à la AD844 from XEN audio
LINK to thread for technical discussion.
PDF with description attached.
View attachment CM IV Description Public 200913.pdf

We need at least 10 sets.
1 set includes 5 PCBs, left / right versions, of which 2 pairs will be supplied. There is an additional "neutral" version which is meant for test build.
and also there will be BOM supplied with PCBs.

Prices:
- 1 set of PCBs will stay at 20€
- 2 channels single (6 matched pairs) + test (not matched) 20€
- 1 PCB set (12 matched pairs) + test (not matched) 25€
- shipping EU - 10€, World - 14€


SPREADSHEET for GB
 
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#7
Please note than for best results, we recommend using very-low-noise regulators for these.
For example LT3045/3094.
These are not included as the version we made was too difficult to hand solder.
Of course you are free to try out other regulator types.
Important is only low noise, not necessarily low output impedance.

For best channel separations, you should use separate regulators for left & right channels.
But to start with just use something simple like On Semi 78L12/79L12, or lab supply.
Once you are happy with the IV, you can play with the power supply.
Batteries also OK.


Patrick
 
#8
Hi,


What are please the average number of transistor needed for a good matching enough according your experience ?


What is the voltage needed : 12V, rigth? The size footprint for the I/V resistor : smd ?



Thanks Ripster, nice GB.
 
#9
From the PDF and pictures from fran I would say they are no more than 20x20mm resistors are 0805 SMD. Also from pdf EUVL said around 15% matching but no number given what was the size of batch so not that good but hey they are not unobtainium. Maybe EUVL can add some mor info on that.
 
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#10
Thanks Ripster.


There is certainly room to experiment on this I/V resistor : thin/thick film, bulk smd, little Philips smd tube type (don't remember the name type, sorry). I don't know if there is a smd trace for an capacitor // to it but a 5 mm lead space with vias could permit good radial LCR brand polystyren cap (Element 14 have them)


cheers
 
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