When you want to adjust the dc power supply circuit voltage up to about 70V.
But the “Cheap adjustable 0-30V 2A Laboratory DC Power Supply” project can fine maximum voltage is 30 volt only.
We need to add more 40V. You do not look difficult. We can adapt very easily, with the addition of just two devices only, and change in the value of equipment a little more.
How to modified this circuit.
When we consider from the original circuit. We can modify this circuit with cutting at point A and B apart.
-Then connect the resistor RX that value of 2K into both point A and B.
-and at point B to connect the zener diode ZD1 value of 18V 0.5W to the ground.
As new circuit modified, In the image below.
Must to change some parts.
We need to change some devices to appropriateness up such as the electrolytic capacitor will must to change to can be durable voltage higher than the original circuit, Which details are as follows.
1. To change the transformer voltage is 50V CT 50V at 3A full current
2. To change the capacitor C1 is 1000uF 80V.
3. To capacitor C3 is 100uF 100V.
How to build.
In the original PCB, we have provided the location, to install these already the more equipment electronics so Just place the equipment correctly and check that successfully is available.
If you want to have 0-50V DC adjustable power supply, be able to see in Power supply regulator 0-50V 2A by IC LM723 + Transistor