Any idea what i can do (audio oriented) with a single secondary 0 - 44VAC toroidal transformer, 290VA..... i have one sitting on the bench....
to save it for something or not - the question is now 🙂
to save it for something or not - the question is now 🙂
Rectify and feed it into a buck regulator to create a single rail variable up to 50V or so.
https://www.aliexpress.com/item/1005005271971237.html
https://www.aliexpress.com/item/1005005271971237.html
Many class D amp circuits / boards run off a single rail DC power supply and that transformer would make about 62V DC unregulated.
If you can get another identical transformer, you can build a dual power supply for a class AB amp in the 150-200W / 8 ohm range.
One transformer for the positive rail and the other for the negative rail. I built an amp this way in the 90's which I still use.
If you can get another identical transformer, you can build a dual power supply for a class AB amp in the 150-200W / 8 ohm range.
One transformer for the positive rail and the other for the negative rail. I built an amp this way in the 90's which I still use.
People love their direct connect speaker burners don't they. I don't: my speakers cost 8 times what my amp did. A new bass driver would be $250. A new tweeter would be $200.
)44 * 1.4) - 1.4 = 60.2 v. Just about perfect for a first generatioin solid state class AB amp like a Armstrong 621 or a dynaco ST120 . The speaker capacitor prevents burning the speaker if a solder joint pops loose (As my diy bike battery charger did today).
With better sound, the Apex AX6. https://www.diyaudio.com/forums/solid-state/236256-retro-amp-50w-single-supply-42.html
I originally improved the poor cold low power idle bias current ST120 with the auxillary 7 transistor djoffe closed loop bias control circuit. However, an AX6 does the job with 6 transistors total. Same 2 output transistors as ST120, remote from the driver board on the heat sink. Much better sound. I run mine at 69 v for 72 watt performance over 5 seconds. 60 v would be more a 50 w amp.
Cap coupled singleton-input amps can sound surprisingly good. They can produce “farting” sounds if driven into heavy clipping with sub bass, but that is outside the range of hi-fi usage. The fix for that is to use a 30,000 uF output cap, a somewhat smaller main reservoir cap, and intentionally roll off the sub-audio frequency gain with the input coupling and feedback caps. With normal music and light or no clipping you can’t really tell it from a DC coupled amp, even with modest caps if you use new ones.
Those singleton input amps can sound a lot better than the usual diff pair input if the pair is mismatched or the currents out of balance.
Those singleton input amps can sound a lot better than the usual diff pair input if the pair is mismatched or the currents out of balance.
Oh yeah, you can make a nice capacitor coupled amplifier which is inherently safe for speakers! @indianajo already made some good suggestion.
would you be kind to share the schematic of how you built that power supply with two transformers... thank you
