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Showing posts from August, 2009

5-18V Stabilized Power Supply

This power supply will give you fixed regulated output at 5V, 6V, 9V and 12V, while the 18V output is unregulated. You could add some regulated IC like LM7815 or 7818 if you need higher output voltage.

This circuit provide an audio indicator that will act like an alarm if any circuit short contact.

General DC Power Supply with uA723

This is the power supplycircuit for general purpose usage.

The supply can be used for supply output voltages from 1 to 35V. The line transformer should be selected to give about 1.4 times the desired output voltage from the positif side of filted capacitor C1 to ground. Potensiometer R2 sets the output voltage to the desired value by adjusting the reference input. Rsc is the current limit set resistor.

For example, if the maximum current output is to be 1A, Rsc=0.65/1.0 = 0.65 Ohm. The 1KOhm resistor,R5, is a light-loaded resistor designed to improve the no-load stability of the supply.

Universal Battery Charger

Battery charger for general purpose usage.

The charger's output voltage is adjustable and regulated, and has an adjustable constant-current charging circuit that makes it easy to use with most NiCad batteries. The charger can charge a single cell or a number of series-connected cells up to a maximum of 18V.

Power transistors Q1 and Q2 are connected as series regulators to control the battery charger's output voltage and charge-current rate. An LM-317 adjustable voltage regulator supplies the drive signal to the bases of power transistor Q1 and Q2. Potensiometer R9 sets the output-voltage level. A current sampling resistor, R8 (a 0.1 ohm/5W unit), is connected between the negative output lead and circuit ground. For each amp of charging current that flows through R8, a 100mV output is developed across it. The voltage developed across R8 is fed to one input of comparator U3. The other input of the comparator is connected to variable resistor R10.

As the charging voltage across the …

Adjustable Power Supply 3-30V/2.5A

This is an adjustable power supplycircuit, also known as variable power supply. . You may use this circuit for general purpose usage.

Here the schematic diagram:

Component list:
R1 = 560R 1/4WC1 = 100nFR2 = 1,2 K 1/4WC2 = 2200uF 35-40VR3 = 3,9 K 1/4WC3 = 100 pFR4 = 15K 1/4WC4 = 100uF/ 35VR5 = 0,15R 5W

D = B40 C3300/2200, 3A rectifier bridgeP1 = 10K potesiometerTR1 = BD 135IC = LM723TR2 = 2N3055

Bottom PCB layout:

Top PCB layout (Components placement):

For complete explanation, circuit's works and how to build this circuit into the box, download the full tutorial here