hi ,
i have this schematic , that works fine with mentioned transistors but now these transistors are obsolete , I have some 2N5401/2N5551 & MPSA92/42 available with me, can i replace them directly , will they heat up too much if i use 70VDC , how do i calculate the current in the VAS stage ?
i have this schematic , that works fine with mentioned transistors but now these transistors are obsolete , I have some 2N5401/2N5551 & MPSA92/42 available with me, can i replace them directly , will they heat up too much if i use 70VDC , how do i calculate the current in the VAS stage ?
Attachments
Maximum power dissipation, W 1145-0,8 5401-0,35 A42-0,625
Doesn't fit. Look at 649/669
Doesn't fit. Look at 649/669
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You looking for ksc3503 F...and its complement which are also unobtainium...I have a somehow similar problem for which I need to source a 2sc2631 for a lower noise applications than yours at high voltage and the only way i can replace that transistor sucessfully is to use 3 paralleled 2sc1775 transistors.That place in particular also need a reasonably high hfe for low distortions.Among my needs there's also a low noise one...
Digikey still shows thousands of KSC3503D and KSA1381E in stock and On Semi website list both as active.
I'd use KSC3503/KSA1381.
I'd also put the whole thing in SPICE, which will make it easy to find currents, etc.
I'd also put the whole thing in SPICE, which will make it easy to find currents, etc.
I don't know what the attached schematic is telling previous replies but all the semis shown are likely generic and suspect Chinese copies currently available cheap from platform sellers. We can expect that only some of these copies, fakes etc. are those intended by the designer and the schematic looks like it was attached to a kitseller's promotional details online. It could be useful to know more details from where the OP found it too.
Just Googling the numbers brings up several Ebay, Ali Express etc. and other affiliated on-line suppliers of these cheap parts so I think you and others here are searching the wrong sources and models. Unfortunately, your guesses are as good as mine regarding the actual parts quality, the unidentified manufacturers or the function and authenticity of the design.
You can simulate the design all you like but the models of the original, obsolete semis which you find on the 'net will not be same for the semis intended here so the only practical way to check out the schematic for performance is buy some examples of the Chinese parts specified then build and test the amplifier design properly. That's not easy and doesn't guarantee success either.
My suggestion - Don't waste your time in trying to copy cheap kits with unknown quality semis.
Just Googling the numbers brings up several Ebay, Ali Express etc. and other affiliated on-line suppliers of these cheap parts so I think you and others here are searching the wrong sources and models. Unfortunately, your guesses are as good as mine regarding the actual parts quality, the unidentified manufacturers or the function and authenticity of the design.
You can simulate the design all you like but the models of the original, obsolete semis which you find on the 'net will not be same for the semis intended here so the only practical way to check out the schematic for performance is buy some examples of the Chinese parts specified then build and test the amplifier design properly. That's not easy and doesn't guarantee success either.
My suggestion - Don't waste your time in trying to copy cheap kits with unknown quality semis.