Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Other Topics => Topic started by: uki on December 18, 2021, 12:50:28 pm
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Really impressive size and power !!
I've found it inside of a LED bulb.
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Thanks for sharing, Nice device MB10F.
Now dare I say: Solder quality 3/10 and board cleanliness 3/10.
Regards
Mirek
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Solder quality 3/10
:laugh:
If I brought something like that to my instructor, I woulda done push-ups til I puked, then I would have to apologize for wasting Government recourses. AFTER I was "dressed down" in the finest Sailor speak imaginable :icon_biggrin:
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Solder quality and board cleanliness....
Oh i forgot to mention, bulb made in china...
believe or not the quality of the components are good, not the work thou.
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ss diodes like that full-bridge surface mount module may not handle as much current as expected from the likes of 1N4007 or WO4 etc as the capability to handle current is so dependant on internal temperature rise, which is so dependant on how the device is mounted. Even common leaded parts like 1N4007 cannot cope with something like 0.5A average even though the datasheet says 1A rating, due to how well the diode leads can conduct the heat out of the part. And the other important aspect is that rectifier diodes don't operate with an average current, but rather a very peaky current pulse which has to be 'translated' in to an average current level in order to assess whether the diode could survive in an amp.
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Correct trobbins. Fairchild says 0.375" (or 9.5mm) lead lengths for 1A current. :icon_biggrin: See attached.
Thanks shooter, I was in a similar situation when I did my traineeship. We were expected to do our own (REAL) quality control ie pass or fail and do it again properly!! Later I had the opportunity to do a JPL/NASA certification in High Reliability Soldering which was a very rewarding experience and set me up for teaching/encouraging newcomers to our joint hobby, building Amp projects we're proud of. (Can I mention Mike from p2pAmps at this stage, as I'm sure his amps have encouraged us).
Kind regards
Mirek
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The subtle difference with ss devices is that if the datasheet limit is exceeded then the part may well fail or degrade immediately. The 1A rating is the limit - go over it at your immediate peril. As such, ss parts should always be operated at a significant de-rating so as not to exceed the limit for typical variations and possible maximum ambient temps.
In contrast most people working with valve amps are used to seeing design centre max limits or similar, where the robustness of a valve rarely ends in damage if a limit is exceeded for short periods, and operation can be continuous at the limit level for the nominal service life of the valve (eg. a few thousand hours).