Power supply

Purpose power supply using LM723

General Purpose Power Supply by L146 or IC 723

This power supply is designed for general purpose use. Advantages of the circuit are first the voltage can be adjusted from 0V to greater and second it does not require a double sided secondary winding transformer.

For high voltage outputs you can use L146 or alternatively if you need lower voltage outputs you can use IC 723. Although output current limit is variable, it will be fixed after adjusted. In the table, suitable component values are listed for three different cases (max. outputs: 30V, 40V and 60V). In the schematic 40V/0.8A example is shown.

2-7V / 6-8A Power Supply by 723 and 7812

In this 2-7V power supply circuit, for our purpose, we chose ua723 regulator instead of a three pin voltage regulator forwhy we find it protean and more advantageous in technical details.

Heatsinks of Tr2 and Tr3 transistors must be sufficiently large.

To achive R4,R5 and R6 values, we used some suitable resistors in parallel. For R4 and R5 two parallel connected 0.3ohm/5W resistors for each are used. To take 6A output, we connected two 0.22ohm/5W resistors in parallel, and to take 8A output we connected three 0.33ohm/5W resistors in parallel instead of R6 resistor.

If you change the marked component values properly you can get up to 14V output. For this situation you must disconnect R1,R2,C5,C6,C1,C2,D1,D2 components and connect the positive terminal of D3 directly to the rectified and stabilized supply….

Source: http://www.circuit-projects.com/

Be the first to comment - What do you think? Posted by admin - April 16, 2012 at 8:27 am

Categories: Power supply, Variable Regulator Tags: general purpose power supply, lm723 adjustable voltage regulator

Precision current sink circuit

This is a current sink circuit that uses a transistor, Jfet and LM101 IC op-amp, so there are high precision.
The 2N5457 Jfet and PN2222 bipolar have normally high output impedance.
The R1 is used as a current sensing resistor, for provide feedback to the LM101 op-amp that it supply a large amount of loop gain for negative feedback, to enhance the real current sink nature.
The value of Iout is : Vin/R1 , by Vin more than 0V.
For low current values, the 10K resistor and PN2222 may be clear out, if the source of the Jfet is connected to R1.

Be the first to comment - What do you think? Posted by admin - March 28, 2012 at 10:51 pm

Categories: Basic electronics, Power supply Tags: current sink circuit

5V to isolated 5V at 20mA converter by MAX635

When we need a constant voltage 5V at the current about 20mA, by there are power supply source voltage about 4V to 6V.
In this circuit, We use the MAX635 IC number is the main equipment, that acts as Preset/Adjustable Output CMOS Inverting Switching Regulators.
At pin A, a negative output dc-dc converter generates a -5V.
First, a negative output voltage dc-dc converter generates a -5V output at pin A.
Then, the primary of the transformer (T1) must fly back to a diode drop more negative than -5V.
If T1 has a tightly coupled 1:1 turns ratio (270uH), there will be a 5V positive voltage at diode across the secondary ‘s T1.
The 1N5817 rectifies this secondary voltage to generate an isolated 5V output.
The isolated output is not fully regulated since only -5V at point A is controlled by the IC1.