Hi folks. I'm building a power supply for a pair of Gefell MV201/MK202 mics. I've got this schematic which people seem to have built successfully:
English: ELEKTROAKUSTIKA® PSU for measuring microphones
Original: ELEKTROAKUSTIKA® PSU for measuring microphones
Suppose I'm pretty familiar with basic tube amp design. A few questions:
1. The caps after the rectifier are really small compared to what you'd normally see in a tube circuit, and I don't see any impedance between them and the rectifier. Are lower values required in a regulated circuit like this? Are these filter caps at all, or are they there for some other purpose? (Does the transistor basically take the place of the cap in terms of supplying current and/or filtering ripple?)
2. Any issue with using this circuit to generate B+ for a tube preamp in place of the traditional R/LC network for filtering and dropping voltage? My forum research suggests it should work well, anti-silicon sentiments notwithstanding. If so--- how should I think about the power rating for the resistors supplying the activation current to the transistors/diodes? My first thought was that current would be low because all the load current is going through the transistor, but they're rated at 2W in the schematic.
3. I'm trying to figure out the max current draw from the mic/preamp itself on the 100V tap. Seems like it should be pretty small, but I'd rather understand how to estimate it at least. That, and I'm using a wimpy little PT for high voltage that can only do 25ma @ 250V. Schematic:
https://www.elektroakustika.cz/mv201.html
How would you go about estimating the current draw of this circuit? I'm thinking of it as R14/2.2K in series with a bunch of parallel branches but realizing I don't know how to think about the transistors' current draw.
Thanks all! Fun project, looking forward to it. Just want to make sure I grasp it fully first.
-Erik
English: ELEKTROAKUSTIKA® PSU for measuring microphones
Original: ELEKTROAKUSTIKA® PSU for measuring microphones
Suppose I'm pretty familiar with basic tube amp design. A few questions:
1. The caps after the rectifier are really small compared to what you'd normally see in a tube circuit, and I don't see any impedance between them and the rectifier. Are lower values required in a regulated circuit like this? Are these filter caps at all, or are they there for some other purpose? (Does the transistor basically take the place of the cap in terms of supplying current and/or filtering ripple?)
2. Any issue with using this circuit to generate B+ for a tube preamp in place of the traditional R/LC network for filtering and dropping voltage? My forum research suggests it should work well, anti-silicon sentiments notwithstanding. If so--- how should I think about the power rating for the resistors supplying the activation current to the transistors/diodes? My first thought was that current would be low because all the load current is going through the transistor, but they're rated at 2W in the schematic.
3. I'm trying to figure out the max current draw from the mic/preamp itself on the 100V tap. Seems like it should be pretty small, but I'd rather understand how to estimate it at least. That, and I'm using a wimpy little PT for high voltage that can only do 25ma @ 250V. Schematic:
https://www.elektroakustika.cz/mv201.html
How would you go about estimating the current draw of this circuit? I'm thinking of it as R14/2.2K in series with a bunch of parallel branches but realizing I don't know how to think about the transistors' current draw.
Thanks all! Fun project, looking forward to it. Just want to make sure I grasp it fully first.
-Erik
