Table of Contents
- 1 How do I create a constant current power supply?
- 2 How can we get a variable DC voltage from a fixed DC voltage?
- 3 How are current sources created?
- 4 What is fixed DC and variable DC?
- 5 What is the need of variable power supply?
- 6 How does a variable power supply circuit work?
- 7 How to create a 20vdc variable voltage output?
- 8 What is the function of potentiometer in variable power supply?
How do I create a constant current power supply?
So to make a device that provides a constant current no matter the load, we have to use negative feedback and convert the current flowing through our load into a voltage. Luckily, there is a very easy way to convert a current to a voltage which involves using a small ohm resistor (in our case, a 0.1-ohm resistor).
How can we get a variable DC voltage from a fixed DC voltage?
- An inverter converts fixed dc voltage to a variable ac voltage.
- In inverter circuits, we would like the inverter output to be sinusoidal with magnitude and frequency controllable.
- These find wide use in induction motor and synchronous motor drives, induction heating, UPS, HVDC transmission etc.
What is a variable power supply?
A variable power supply is one which includes some means for the user to easily adjust the output voltage and sometimes the current. Adjustment is most often accomplished with a potentiometer, but may also be done with an analog control voltage, a digital input, an autotransformer, etc.
How are current sources created?
A current source can be made with a current mirror, where two BJT transistors are biased with the same base-emitter voltage to give the same (well, almost, the difference is two base currents) collector current.
What is fixed DC and variable DC?
Answer: A battery is a fixed DC supply, within its rated working voltage. Rectified DC output from AC supply source without smoothing is a varying DC , not variable. By variable supply we mean a supply whose voltage or current can be varied by some means, and is not fixed once for all.
What is a variable power supply circuit?
What is the need of variable power supply?
Using a variable/programmable power supply allows digital or analog control of the power supply output by a control system for maximum versatility. The control system can control and monitor the power supply output voltage and current from virtually anywhere there is an Ethernet connection.
How does a variable power supply circuit work?
A variable power supply circuit is built with variable positive voltage regulator LM317, CMOS decade counter IC CD4017, timer IC NE555 and fixed negative voltage regulator LM7912. The AC supply is fed to the transformer which is stepped down to 12V AC.
What is the maximum current in a universal power supply?
The above universal power supply circuit provides a variable voltage between 3 to 30V, the maximum current of 1.5A and addition of modules can provide a higher current. The adjustable voltage regulator LM317 (U1) offers short circuit.
How to create a 20vdc variable voltage output?
It must still exceed the voltage of the DC which we want to output. Since we want to create up to 20VDC variable voltage output, we need a transformer that converts the mains voltage to a voltage that is higher than this 20V.
What is the function of potentiometer in variable power supply?
Usually, a potentiometer is used for voltage adjustments. The variable power supply circuit is equipped with an adjustable voltage regulator to adjust the output according to the output. An adjustable voltage regulator has line regulation and load regulation. This block diagram shows how the AC voltage is regulated in the circuit.