I need a 24vdc, 5 amp regulated supply

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Any good circuits ?

I would recommend a LM338 on a suitable TO3 case large heatsink
use a transformer with a 22vAC tap provide it with a full wave rectifier,
and derive 24 V DC, diagram attached.

Of course there are many other circuits possible, but parts count
is low and reliability is pretty well, set and forget.

Cheers / Chris
 

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according to your link it ships with a SMPS & it's a 2x20W amp right? I reckon class D is at least 80% eff. unless u have 2 ohm speakers, so 120W linear maybe overkill, I figure 1 $ /Watt for DIY parts, less if you have a donor case and big junk drawers.
 
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Hi
do want to build one or buy one? I have schematics you could modify if you know basic electronics theory. FWIW since 24V is a standard, you can probably pick up a new or used one for cheaper than you could build. Also many cheap linear lab supplies are 0-30V at 5A some brands may be problematic and might have noisy fans etc
 
Hi infinia,
I was thinking along those same lines. You can get an open frame 24VDC power supply fairly inexpensively in surplus stores. "Open frame" means that the chassis is simply the frame with the transformer and PCB + output transistors mounted on it. It is designed to bolt to the chassis of the device it is being built into and that provides the heat sink surface as well. Most often the frame is like three sides to a box with the rest open. I find them convenient when I need a quick fix for a missing power supply.

These power supplies are very high quality and generally have a very clean DC output. Some even include a "crowbar" for output protection. If the voltage climbs too high, the SCR across the output is fired. That generally blows the fuse.

-Chris
 

Hi, John

I have been playing around with these 3116/3118 amp boards (from EBAY/Taobao/Aliexpress) for a while now. They work fine with a laptop brick or the usual SMPS (I have used 12 V, 19 V, and 24 V). The PSU ripple noise rejection is -70db, which is decent. There are 4 available gain settings (20, 26, 32, 36 db). At the highest gain setting (36 db), one can start to hear some noise. However, at the typical 26 db or 32 db setting, noise is generally not an issue (I tried both). The chip is very efficient. If your speaker is reasonably easy to drive (e.g. 87 db or higher my experience), you do not need a big PSU.

I suggest you try out the PSU that comes with the amp, if you hear that the amp is "starved", then get a bigger PSU. These little amps sound quite good for the money. Have fun.

My 2 cents.

Regards,
 
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