To stabilize the voltage, I used 7805 and 7812 regulators. These are easily connected and used. They also allow the external transformers to be approximately +12 – +30 volts.
The condensators must be placed as close as possible to the regulators. This prevents possible oscillation of the circuit.
The adjustable side (the red section) was made as a emitter follower. This leads to a very simple, yet powerful, structure. The potentiometer is linear by its type. The transistors in use can easily be switched to corresponding ones. The BC547 transistor (ie. NPN transistor) can be replaced by almost any cheap NPN transistor. The BD442 PNP transistor should be replaced only by a transistor that has enough current endurance.
As the fuse, I used a normal 500 mA glass fuse.
?So, the connectors are drawn the way they are when you look at the back panel of the computer. The keyboard and mouse have an identical pin order, so the gadget doesn’t require two separate ps/2 connectors.
Note that the intention of all of this is to use the connectors as sources of voltage. The datalines of the connectors aren’t plugged or connected anywhere.
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