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Old 10th August 2012, 09:56 AM   #6661
FdW is offline FdW  Netherlands
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Originally Posted by Joachim Gerhard View Post
The Leds are 3mm 2mA. You can order Osram, Knightbridge, whatever. I use Reichelt because they usually are in the lower price range. You can even order surplus from Pollin.
I use 1uF MKT from WIMA; also Reichelt. You have to watch the footprint. In the PSU there is an option, in the Phono part, not. 7.5mm is fine. EPCOS, RIFA, are other options. They perform more or less the same. If you want P-P use WIMA MKP4, they are the smallest.
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Originally Posted by Joachim Gerhard View Post
Most green Leds with 2mA nominal have a forward drop of around 1,8V.
Quote:
Originally Posted by jacco vermeulen View Post
Near all green led's will do, if they handle at the least 1mA current. Near all green led's will have a forward drop of (about) 1.7 volts (and that will do).
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Old 10th August 2012, 10:40 AM   #6662
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Originally Posted by FdW View Post
Near all green leds
Oh Well, 10mm ones then.
(shame that a 20mm does close to 6V at 2mA)
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Old 10th August 2012, 10:46 AM   #6663
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Thank you Frans and Jacco

This is what I needed to know " if they handle at the least 1mA current."

How far can we go from the 1.7 Vdrop margin ?

I am using yellow leds.. did not measure them but these could have higher Vdrop (1.8 to 1.9)
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Old 10th August 2012, 11:25 AM   #6664
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Thank you Frans and Jacco

This is what I needed to know " if they handle at the least 1mA current."

How far can we go from the 1.7 Vdrop margin ?

I am using yellow leds.. did not measure them but these could have higher Vdrop (1.8 to 1.9)
As far as you dare and if the output voltage gets to high, you can just use one less (and bridge the open spot in the chain of led's).
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Old 10th August 2012, 11:27 AM   #6665
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Originally Posted by jacco vermeulen View Post
Oh Well, 10mm ones then.
(shame that a 20mm does close to 6V at 2mA)
I would presume that the 20mm one holds actualy 3 leds (don't you think, but I have been wrong before ).
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Old 10th August 2012, 11:33 AM   #6666
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Thank you again

I do not see placement for C91 and C92 on the board... Guess these filtering/decoupling caps for the opamp psu lines proved irrelevant right ?
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Old 10th August 2012, 11:40 AM   #6667
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I would also like to experiment several types of caps in the output of the shunts... there is a 10uF... can I use very low ESR types ? .... Will it withstand a film cap without oscilating ?
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Old 10th August 2012, 11:50 AM   #6668
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Quote:
Originally Posted by FdW View Post
I would presume that the 20mm one holds actualy 3 leds
Three 20mm LEDs on each side may look pretty too.

(are you implying that I am able to think ?)
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Old 10th August 2012, 11:57 AM   #6669
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I would also like to experiment several types of caps in the output of the shunts... there is a 10uF... can I use very low ESR types ? .... Will it withstand a film cap without oscilating ?
It is not advised to use low (and very low) esr types on the output of the shunt, other shunt designers say that it may even be better to leave the capacitor out. My opinion is that the best practice is to install a 'normal' 'high ' esr type it's purpose is mostly to suppress (lower the output impedance of the psu) at high frequencies (> 1 Mhz). One replacement I would like to see tested is, a 2 Ohm resistor in series with a high quality 5..10 uF capacitor.

On the other hand, no one has been able to make this thing oscillate so try it and I already did some weird thing to it (including using more than 2 M of intertwined wire between the PSU and the attached electronics).
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Old 10th August 2012, 12:48 PM   #6670
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I used a 10uF 35V Panasonic FM without problem. I measured the ESR to be around 1 Ohm with this cap.
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