I just "inherited" a toroidal transformer from a friend. The bad news is it is single output 15 VAC. The good news is it rated 650 VA. I would love to try my hand at any Pass Amplifier build, the last one I did was when the A40 was new in Audio Amateur. I know the voltage is silly low but since I do not have an Encyclopedic know of the many Pass designs I just figured I'd ask the experts if there was something I could do with it.
Maybe the MoFo…….12 - 24 VDC should be OK for this……650VA should be fine for two channels…….look for MoFo in the Thread overview.....
From the MoFo description:
Wow, that [FONT=Arial,Arial][FONT=Arial,Arial]is [/FONT][/FONT]simple," I said, "but what about the power supply?"
"Just use one of those laptop switchers," he said "that’ll be great for beginners. You could use anything decent from like 12 to 24 volts."
"Oh, great, but don’t those have a lot of ripple, Dude?" I asked.
From the MoFo description:
Wow, that [FONT=Arial,Arial][FONT=Arial,Arial]is [/FONT][/FONT]simple," I said, "but what about the power supply?"
"Just use one of those laptop switchers," he said "that’ll be great for beginners. You could use anything decent from like 12 to 24 volts."
"Oh, great, but don’t those have a lot of ripple, Dude?" I asked.
content with 15Vpp voltage output ?
that's 3.5W/8R and 7W/4R
go for low power MoFo - having inductor as loading is compensating low PSU voltage , in few ways
edit: Meper got it right , faster
that's 3.5W/8R and 7W/4R
go for low power MoFo - having inductor as loading is compensating low PSU voltage , in few ways
edit: Meper got it right , faster
Secondaries are usually wound on the outside winding layer so you can add a few turns and increase the out put voltage some. You may be surprised how few turns will make relatively big output change.
OR?? you could simply treat the thing as another mans' Trash.. and gasp! Buy a suitable Antek for ~40$
it is tough to contemplate what to do with a part, when a more suitable one could be had for a few bucks. Perils of the hobby.
15VAC to FWB and cap makes 20V DC. Big car-sound amp.
15VAC to 2-diode 2-cap voltage doubler makes +/-20V or 40V total.
40V between rails in a straight totem-pole amp makes 25 Watts in 8 Ohms.
40V between rails in a bridge-tied amp makes 100 Watts. Two channels (four amplifier units) of that begins to justify a 650VA lump.
I dunno what Pass has published in a lower-voltage high current amplifier which could be bridged.
15VAC to 2-diode 2-cap voltage doubler makes +/-20V or 40V total.
40V between rails in a straight totem-pole amp makes 25 Watts in 8 Ohms.
40V between rails in a bridge-tied amp makes 100 Watts. Two channels (four amplifier units) of that begins to justify a 650VA lump.
I dunno what Pass has published in a lower-voltage high current amplifier which could be bridged.
You could also get a main 2 kVA isolation trafo that has multiple outputs and maybe up to double the main normal input. In US you have 115 VAC as normal? ….then if you get 115, 135, 155, 175 VAC outputs it gives some possibilities to reuse trafoes. I have thought of getting such a trafo myself. E.g. in the moment I have two PSUs with LCLC filtering for the ACAs. They give about 24 VDC at 1.5A. If I pull 2.5A the voltage drops to about 20 VDC. Still with very low ripple (about 1 mV). Then if I got a main isolation trafo with multiple outputs I could raise the main voltage by 25% and get back to 24 VDC output and then reuse the PSUs for the MoFo which I plan to build (20 VDC would work also for the MoFo).
increasing input voltage to xformer is rarely wise thing ....... first buzz , then smell , then (quick) BigBadaBoom
I wouldn't be surprised if such a big transformer has more than one secondaries connected in parallel. Have you checked that? It would mean a proper symmetrical psu.
Good point, parallel windings is probable see that single winding would require very heavy gauge magnet wire to flow something like 43amps. Not at all easy to wind. Are the output winding leads stranded wire or solid enameled magnet wire. If stranded it may be worth unwrapping the tape and checking for parallel secondary windings.
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