jacco if you bring some of your toys along and are willing to face the crime corruption & murder you're welcome 
I think the diode group buy will make life for everyone easier and cheaper so if Mark'd be generous once again...
Those wishing to opt for the J509 should just note that it's a TO92 package so it'll have to be stretched out and modified to fit the axial component provided for on the board.
I think the diode group buy will make life for everyone easier and cheaper so if Mark'd be generous once again...
Those wishing to opt for the J509 should just note that it's a TO92 package so it'll have to be stretched out and modified to fit the axial component provided for on the board.
PWatts said:
Pierre,
my favorite childhood books, still have the entire Fritz Deelman series : www.roekeloos.co.za/boekrak/boekra67.html
In Afrikaans, of course. For some reason he's called Frits in our local Kak praat.
Have you already mentioned how to solder the SOT223 parts on the bottom of the board ? Seems i've missed that.
Loek,
you called the Vishay distributor in NL for samples ?
Hahaha I remember.. loved Fritz Deelman en die Groen Dood
About soldering the SOT packages.. uhm... didn't know it needed instructions
Important thing is to _slightly_ wet the three leg pads with solder or preferable solder paste. Keep about 1mm of the pad exposed. Press the body down and solder the middle pin, and if it sits well the rest. Make sure the whole thing is flat on the board of course. Leave it as it is until the amp is working, and once you're sure everything's OK, apply liberal amounts of solder at the top until the tab itself is also slightly covered. You can also make sure the vias are fully filled by soldering them from top side of the board.
Note that although the tab soldering creates a proper heatsink, it'll also take a fierce amount of oomph to remove it, so once it's on, it's ON. If it blows for some reason later on, I'd rather just heat and lift the three legs and go for one of the other two packages left open than to try removing it with a blowtorch.
About soldering the SOT packages.. uhm... didn't know it needed instructions
Important thing is to _slightly_ wet the three leg pads with solder or preferable solder paste. Keep about 1mm of the pad exposed. Press the body down and solder the middle pin, and if it sits well the rest. Make sure the whole thing is flat on the board of course. Leave it as it is until the amp is working, and once you're sure everything's OK, apply liberal amounts of solder at the top until the tab itself is also slightly covered. You can also make sure the vias are fully filled by soldering them from top side of the board.
Note that although the tab soldering creates a proper heatsink, it'll also take a fierce amount of oomph to remove it, so once it's on, it's ON. If it blows for some reason later on, I'd rather just heat and lift the three legs and go for one of the other two packages left open than to try removing it with a blowtorch.
Do you all think that the Vishay devices have a high enough POV to them? If all here are comfortable with them they are also alot less expensive... If there are those thata re not comfortable with the 50 volt rating them I can do a small G.B. on the 1N5309's. We could add the diode G.B. in on the present WIKI.
Also I updated the WIKI with much of PWatts suggestions and ideas as well as a method for removing the SMT devices that I normally use.
Mark
Also I updated the WIKI with much of PWatts suggestions and ideas as well as a method for removing the SMT devices that I normally use.
Mark
assuming I'm understanding whats happening in the circuit correctly:
Under idle conditions I think you will see <30v across the diodes, the voltage being derived from the values of the front end zeners, the voltage drop in the LTP collector resistors, the need to turn on the fets, and the voltage drop in the fet resistors.
The current diodes precede the VAS, so shouldn't see huge voltage swings in normal operation, but I haven't put any thought into what happens under startup/shutdown and overload conditions.
HTH
Stuart
Under idle conditions I think you will see <30v across the diodes, the voltage being derived from the values of the front end zeners, the voltage drop in the LTP collector resistors, the need to turn on the fets, and the voltage drop in the fet resistors.
The current diodes precede the VAS, so shouldn't see huge voltage swings in normal operation, but I haven't put any thought into what happens under startup/shutdown and overload conditions.
HTH
Stuart
Stuart Easson said:
If I may say something it would be the following: If Krell has made a choice their choice for the the 1N5309 must have been for a reason.
Stuart, your suggestion regarding idle condition Im sure this is a right conclusion , but I am sure Krell has calkulated the DATA for ALL THE SEMICONDUCTORS under worth possible conditions and this also include the 1N5309 constant current diodes dont you think? What should we expect of transient voltage and peak current if calculating the components under extreme clipping or short circuit. What would the data looks like then?
If calkulating semiconductors under idle conditions and not the worth possible conditions, all solid states amps should blow upp very fast if conditions change from idle to to full load, high temp or low impedance.
Just some (a couple of cents) thoughts.
regards
PS Thank you Mark for your effort and Im looking forward to receive those beautiful Krell KSA100 mk-II boards. DS