I have long wanted to make an adjustable laboratory DC power supply. And he developed a circuit (for 2 voltage ranges) and the transformer was wound ... but in temporary workflow it is also used as a work-off, either for charging batteries, or for powering in a primitive ... And I saw DIY assembled on type Kit. Also with adjustable current protection. Ordered, received by mail. I connected it to an existing unit with a transformer (non-separable), which gives out ~ 18 V. Instead of the ~ 24 V. required by the description, I first put the power transistor on the radiator, as it is written in the description. And it must be blown with an additional fan. As a result, I fixed the transistor to the case-radiator (shown in the photo). Everything works. The LED indicator will also need to be displayed on the case.
Device characteristics (from the seller, with my revision):
Input voltage: 24 VAC
Input current: 3A maximum
Output voltage: 0 .... 30 V continuously adjustable
Output current (limitation): 2mA-3A continuously adjustable (?)
Output voltage ripple: minimum 0.01%
Everything is directly inserted element, easy to make, only adjustable components are added. The LED indicator serves to indicate the output current overload. When the current exceeds the set value (Rvar), the short circuit protection is activated and the LED lights up.
The circuit is not attached, but all the details are signed on the printed circuit board ...
Cost: ~ 505