Elenco's XP-720K Power Supply Kit

The XP-720K power supply features three solid-state DC supplies. Two DC supplies are positive and negative 1.25 - 15 volts at 1 ampere. The third has a fixed 5 volt at 3 amperes. There is one integrated circuit regulating each DC supply for a total of three integrated circuits. In addition, the supply has two 6.3 volts alternating current supplies that are taken directly from the transformer; moreover, the transformer steps down the 120VAC input to 17VAC, which is delivered to the AC to DC converter. This converter consists of two diodes and a 2200 microfarad capacitor. To conclude, this supply was fun to build and is about all I would need on my work bench. I think any lab or work bench would find it useful. Lastly, I like the small profile and the look of the control panel. Below are the assembly pictures, and the testing information for the power supply. I also included the watt reading's of the supply during the testing phase.  

 Assembly

Heat sink with IC and transistor

PC Board completed 

Transformer wired to fuse and switch

PC Board wired into Transformer, Binding Posts, Potentiometers, ICs, and Transistor

Completed XP-720 Power supply. 

Testing

Testing the Positive Variable DC 1.25-15V low end

Testing the Positive Variable DC 1.25-15V high end

Testing the Negative Variable DC -1.25- -15V low end

Testing the Negative Variable DC -1.25- -15V high end

Testing the 5VDC 

Testing first post 6.3VAC

Testing second post 6.3VAC

 LOAD TEST #1

The first test is to set the voltage at 10V and connecting a 10 ohm, 10 watt resistor from the output to ground. The output should not change more than 0.20 V. The results was a change of - 0.13 --acceptable. The watt reading was not part of the testing, but I recorded how many watts the power supply draws from the outlet, which was 37.7 watts.  

Dialed in load test voltage for 10 ohm, 10 watt resistor

Load tested at 9.88VDC 

 LOAD TEST #2

The second and last load test was the 5VDC. This test required connecting a 2.5 ohm, 12 watt resistor from the output to ground. The output should not change more than 0.20V. 

The result was a change of - 0.11 --acceptable. And the watt reading was 37.2.

Reading before load test of 2.5 ohm, 12 watt resistor

Load tested at 4.84VDC