Variable Regulator

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

Stable Zener Reference

Nowadays some first-rate voltage references are available. Take the LM385 for example: this is available for different voltages and even comes in an adjustable version. What is more, the current consumption may be kept very small (10 µA). But as often happens, you may not have one to hand when you need one for an experimental circuit. In that case, you could use an ordinary zener diode for the reference. Unfortunately, they have a somewhat higher internal resistance (about 5 ?), which means they won’t be very stable when the supply voltage varies. The solution is right in front of us: use the stabilised zener voltage as the supply voltage! This is obviously only possible if the stabilised voltage is higher than the zener voltage.

It therefore has to be amplified a little. This is exactly what this circuit does: it amplifies it by a factor of two. The current limiting resister should be chosen such that a current of 1 to 3 mA flows through the zener diode. Manufacturers usually state the zener voltage at a current between 3 to 5 mA. The zener diode is fed from a stabilised voltage and hence has a very stable operating point, which is independent from the supply voltage. The graph speaks for itself. It is clear that the output voltage is much more stable. The graphs have been plotted to different scales to make the comparison easier. In reality the opamp output is twice the zener voltage. Zener diodes also have a temperature coefficient, which is smallest for types with a zener voltage around 5 volts. Virtually any type of opamp should be suitable; even our old friend the 741 works well enough.
Author: Karel Walraven
Copyright: Elektor Electronics

Be the first to comment - What do you think? Posted by admin - October 20, 2010 at 11:29 pm

Categories: Power supply, Variable Regulator Tags: voltage reference circuit, Zener diode regulator

Adjustment power supply values 1.25-15V Max current 0.5 amp

This is power supply that have Voltage output fine the value has 1.25-15V. From by Output current that be valuable about 0.5 amp that 12V and 0.2 amp that 15V.
When Volt , from 220V houses reach transformer. It will modify Volt 220V to be 18VAC already to change rectifier circuit. Which D1, D2, C1 and R1 wasp be Full wave rectifier circuit. For modify DCV to ACV to a signal DCV. It make get a signal DCV that have voltage at pin 3 of IC1 be 20V. From that time DCV signal this reach fight DC Regulator circuit. Which use IC number LM317. This circuit will perform to maintain one’s position Voltage smoothly. Which level output voltage at get this will go out the way pin 2 of IC1. By have capacitors C2 be voltage filter in order that voltage output level of the circuit is will high class modify to follow fining. The performing fee withstands VR1 there.