Mpp

[RCruz]

As for k170... can I use BL grade ?

What should be the ideal Idss ?

[Joachim Gerhard]

I am sorry to hear that.

[Joachim Gerhard]

Idss is not that critical in this application. I would say 6mA to 9mA is fine.

[RCruz]

Perfect... I have lots of those

This new paradise r2 works at 18v... so considering shunt vin vout I should feed something like +-28V raw DC right ?

[FdW]

Originally Posted by RCruz

Perfect... I have lots of those

This new paradise r2 works at 18v... so considering shunt vin vout I should feed something like +-28V raw DC right ?

Yes.

BTW I'm sory to hear about the R1 transistor replacement failing? Did you you first cut the legs and than remove them one by one, or did you try to remove the transistor in one go?

[Joachim Gerhard]

Yes, cutting the legs first is safer.

[RCruz]

I know that but it seems the legs have been cut before.... it was not good already.

To repair it I must remove the heat sink and redo the pads with external wires... I do not think it is worth the effort becuse in the end, the trouble might not be confined to the shunt as it was producing the correct +-24v... I always had trouble with this channel.... the other one worked from day one but not this one.

I will forget it for a while and build the paradise r2 now

[FdW]

Originally Posted by RCruz

I know that but it seems the legs have been cut before.... it was not good already.

To repair it I must remove the heat sink and redo the pads with external wires... I do not think it is worth the effort becuse in the end, the trouble might not be confined to the shunt as it was producing the correct +-24v... I always had trouble with this channel.... the other one worked from day one but not this one.

I will forget it for a while and build the paradise r2 now

One thing more about removing stuff from a board; do use a temp controlled soldering iron! Other irons will get to hot and damage the board. (Just posted for general interest )

[RCruz]

Today I removed the heatsink... not a big deal after all

But now I found that hesener did change radically the negative shunt .... I did not know that and my attempt to get the correct voltages might have been very wrong.

Must speak with him to understand the mods.

[Joachim Gerhard]

I am sorry that the first Paradise version gives such trouble. They work in Heseners setup but as soon as they have left the creator they have a life of their own.
The new version does not present problems so far.
I have a little project where i plan to use the ATL Mini Shunts. I found two little bugs :
First : the BD transistors have to be turned 180 °
Second : I set the ouput voltage with two 12V Zeners and supply the Shunts with my Nobrainer Preregulator. I put on dummy resistors to simulate a load of 20mA.
Under this condition i get plus 11.4V and minus 11.7V. I then measured the voltage over the Zeners and that was quite different. This behaviour is not critical when we supply integrated Opamps. They can stand quite an asymmetric supply. My problem is that i want to supply a preset discrete SMD buffer that has some offset when voltages are not the same. I could select the Zeners of cause. My question to Frans is if there is a posibility to fine tune the symmetry with other means.