Michael Tibes
Well-known member
Some questions which are puzzling me:
-What difference does it make to use BC 550C Transistors instead of the BC 107 types?
My knowledge isn't sufficient to judge it theoretically - as far as I understand they should have more gain and be quieter. But I certainly might overlook something I'm not aware of. Juergen Haible uses them on his 1176 inspired project as well.
-Does the BC 560 have to be any specific type (a,b,c?)?
-Do the fets for the audio gain reduction and the gr meter driver have to be matched, if so, how closely?
-Is it better to have higher hfe types for the output transistors (BD 139/140-16)?
-Is it of any benefit to select a pair with the same hfe for the output and will a normal hfe tester in a multimeter be sufficient to do so?
-What sensitivity should the VU have? Does it have to have rectifier diodes on the meter (I believe some 'real' VUs have that)? If so, what type of diode? 1N4148 or something with a lower breaktrough voltage?
I have a bunch of cheap VU style meters lying around but don't know whether they fit electrically.
I hope that maybe some of you guys can help me with that - thanks a lot!
And a big big thank you to mnats - I received his boards which are great and he handled everything very fluently and fast (even the shipment from australia to germany). It's great to diy 'worldwide'!
Michael
-What difference does it make to use BC 550C Transistors instead of the BC 107 types?
My knowledge isn't sufficient to judge it theoretically - as far as I understand they should have more gain and be quieter. But I certainly might overlook something I'm not aware of. Juergen Haible uses them on his 1176 inspired project as well.
-Does the BC 560 have to be any specific type (a,b,c?)?
-Do the fets for the audio gain reduction and the gr meter driver have to be matched, if so, how closely?
-Is it better to have higher hfe types for the output transistors (BD 139/140-16)?
-Is it of any benefit to select a pair with the same hfe for the output and will a normal hfe tester in a multimeter be sufficient to do so?
-What sensitivity should the VU have? Does it have to have rectifier diodes on the meter (I believe some 'real' VUs have that)? If so, what type of diode? 1N4148 or something with a lower breaktrough voltage?
I have a bunch of cheap VU style meters lying around but don't know whether they fit electrically.
I hope that maybe some of you guys can help me with that - thanks a lot!
And a big big thank you to mnats - I received his boards which are great and he handled everything very fluently and fast (even the shipment from australia to germany). It's great to diy 'worldwide'!
Michael
