This regulated supply needs no mounting hardware.
The circuit shown above is for a positive regulated DC supply that uses commonly available components. It is a variation of a well known design, but differs in the fact that it uses a negative three-terminal regulator (79xx etc) and a 2N3055 NPN 'pass' transistor which is directly chassis mounted. This provides a heatsink, and establishes the ground point of the circuit through the Collector's metal case mounting point. The advantage being of course; no insulating mounting hardware for the 2N3055 is required. It should be noted that this arrangement precludes an incoming (unregulated) voltage that has the negative side tied to chassis ground (standard practice) - i.e. a floating input is needed. Minimal current flows through the 3-terminal regulator, so this need not be heatsinked. Because of its simplicity, there is no real over-current protection, so any short circuits on the output would be best avoided! Use a 3-term regulator from the 79xx family, available 5, 8, 12, 15, 24 volt etc, the incoming DC supply voltage should be 20% - 50% higher than the regulated dc output voltage, for efficient operation and ensuring that there will be sufficient current available to supply the load.
If you have any questions related to this project then please refer them to the author Frank V. Hughes.
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