A very simple variable power supply circuit can be constructed using this electronic circuit diagram . This Circuit is use common components and is very simple to design . This variable regulator circuit will provide an variable regulated output voltage , between 0 and 50 volts . The CA3140 operational amplifier compares the regulator output to a reference voltage , that depends on the R9 value . The output voltage will be nominally twice the voltage between the positive input ( noninverting ) of the CA3140 and ground . The unregulated input voltage must be around 60 volts . The output voltage can be set between 0 an 50 volts using R9 potentiometer . The 2N3055 transistors must be mounted on a heatsink , to prevent the overheating of transistors .
A very simple and interesting 16 volts power supply can be made using this circuit diagram that is based on the MAX668 constant-frequency, pulse-width modulating (PWM), current-mode DC-DC controller that is designed for a wide range of DC-DC conversion applications . The MAX668 integrated circuit supports a wide input voltage range from 1.8V to 28V .
In some electronic circuits we need a 9 volts power supply , but we need to use a battery if that device is mobile . In many cases we don’t have a 9 volts battery or we don’t have enough space to put a 9 volts battery inside the device , so this case we can use a this inverter circuit that will convert 1.5v to 9v to take the place of those expensive 9v batteries.
The input voltage for this inverter can be from 1.5 volts , up to 4.5 volts . When no current is being drawn from the output the current is less than 10mA.
This inverter circuit is very simple requiring few components , but it can be used only for projects that require low current . The L1 coil must have 60 turns on a 10 mm ferrite slug 15 mm long , using a 0.25 mm diameter enameled wire .