Panel switch wiring

The circuit design was intended to create an adjustable power supply over a range of 1.3V to 12.2V at 1A and be able to provide protection for over-current by utilizing LM723 regulator.


 Terminology

• LM723 – a positive NPN standard voltage regulator mainly designed for series regulator applications which can be utilized for both foldback and linear current limiting due to its very low standby current drain circuit
• Voltage Regulator – an electrical or electronic device created for the purpose of maintaining a constant voltage level of a power source within the suitable limits
• 2N3055 – a complementary Silicon Epitaxial-Base planar NPN transistor mounted in Jedec TO-3 metal case for use as power transistor

Circuit Explanation
The integrated voltage regulator LM723 will supply 150 mA of output currents but any desired load current can be provided by adding external transistors for output currents in excess of 10A. This can be used as a linear or switching regulator since its output voltage can be adjusted from 2 Volts to 37 Volts while the input voltage can be at 40 Volts maximum. The range of variations of input voltage and load current can be kept at constant using this voltage regulator.

In this design, the DIL14 plastic packaged LM723 performs with 9.5V to 40V input DC voltage while having an output voltage that is not more then 6V to 7V below the input will lead to 150 mA current source from  the IC. The difference between the input and the output DC voltage plus the current is proportional to the amount power being dissipated by the transistor T1 as it accepts all the current brought by the load, thus requiring a heatsink with a heat conductive value of 5K/W. T1 is made from 2N3055 which is intended for series and shunt regulators, for output stages and high fidelity amplifiers, and for power switching circuits. The output stage of the integrated circuit will be less loaded when an external pass transistor is used which will conduct at emitter-follower mode. This will in turn cause T1 to conduct at base-emitter mode thereby producing a major resistance in the IC.

Both ceramic capacitors must be positioned closer to the integrated circuit to prevent undesired oscillations, which the LM723 is prone to, since ceramic capacitors have high frequency coefficient of dissipation. Having these capacitors directly soldered would be too much for the IC since the operating temperature of the IC is in the range of -55ᵒC to +125ᵒC

Application
Voltage regulators are used for several advantages in areas where uncontrolled voltage varies more than the accepted voltage of equipment which could be harmful and damaging. In motor vehicles, it matches the charging requirements of the battery and electrical load to the output voltage of the generator by rapidly switching from one to another of three circuit states using a dual pole switch loaded with spring. To keep a recommended range of voltage supplied to a consumer, regulators are used by alternating current distribution feeders or large scale power distributions or substations. This is useful in protecting the equipment using electricity by minimizing the variations in voltage.  The two types of regulators being used are step regulators where the current supply is controlled and the induction regulator where an induction motor adjust the voltage by supplying a secondary which smoothens the feeder line’s current variations.
The LM723 voltage regulators are widely used for wide range of applications such as a temperature controller, a current regulator, or a shunt regulator. Also, DC power supplies in electronic equipment are using voltage regulators.

Source:zen22142.zen.co.uk/Circuits/Power/723psu.htm

9 Volt DC Power Supply Using LM317 Regulator

In the following schema scheme, we can see the typical basic application into obtaining voltage can be adjusted.

This is a small variable power supply delivers adjustable output voltage of 1.3v-12v. The current output determined by R3. With current setting (see part list), it will deliver current output about 1A.



Detail Specification:
Output (approximate values):

Vmin = (R4 + R5) / (R5*1.3)
Vmax = (7.15 / R5) * (R4 + R5)
Imax = 0.65/R3
Max. Power on R3: 0.42/R3
Min. Input DC Voltage (pin 12 to pin 7): Vmax + 5

Parts List
B1 = 40V/2.5A
R1 = 1k ohm
R2 = Potensiometer 5k ohm
R3 = 0.56R/2W
R4 = 3.3k ohm
R5 = 4.7k ohm
C1 = 2200uF (3300uF even better)
C2 = 4.7uF
C3 = 100nF
C4 = 1nF
C5 = 330nF
C6 = 100uF
D1 = Green LED
D2 = 1N4003
F1 = 0.2A F
F2 = 2A M
IC1 = LM723 (in a DIL14 plastic package)
S1 = 250V/1A
T1 = 2N3055 on a heatsink 5K/W
TR1 = 220V/17V/1.5

R2 sets the output voltage. The maximum current is decided by the value of R3: the over-current protection schemary inside the LM723 senses the voltage across R3 and starts shutting the output stage off as soon as this voltage approaches 0.65 V. This way the current through R3 can never exceed 0.65/R3, even if the output is shorted.

C3 and C4, both ceramic, must be placed as close as possible to the integrated schema, because the LM723 can be prone to unwanted oscillations. It is not an overkill to solder them directly (and very carefully) to the pins of the IC. All other connections should also be kept short.

The LM723 works with input DC voltages from 9.5 to 40 V and the IC itself can source some 150 mA if the output voltage is not more than 6-7 V below the input. When an external pass transistor is used (in the usual emitter-follower mode), the base-emitter junction of T1 represents a significant resistance and the integrated diagram output stage is relatively lightly loaded. All the current drawn by the load passes through T1 and it dissipates an amount of power that is directly proportional to the current and the difference between the input and the output DC voltage.

The fixed voltage power supply is useful in applications where an adjustable output is not required. This supply is simple, but very flexable as the voltage it outputs is dependant only on the regulator and transformer you choose. The maximum output current is 1.5A. Fixed Voltage Power Supply Circuits diagram :   Parts : Part    Total     Description C1           1       2200uF 35V Electrolytic Capacitor C2, C4     2       0.1uF Ceramic Disc Capacitor C3           3       10uF 35V Electrolytic Capacitor

D1, D2    1        1N4007 Silicon Diode

BR1        1        2A 30V Bridge Rectifier

U1          1        Regulator (See Notes) T1          1        Transformer (See Notes) S1          1        SPST 2 Amp Switch F1          1        2A 250V Fuse and Holder  Misc      1        Heatsink For U1, Line Cord, Case, Wire  

Notes :

1. Since this project operates from 120 (or 220, or 240, etc.) volts AC, it MUST be built inside a case.
2. U1 will reauire a heatsink.
3. You will need to choose T1 and U1 to match the voltage you want. Use the table below as a reference.

Power supply Circuit

Part List
R1 - 1.8K 1W
R2 - 100Ω
C1 - 0.47µF 400V
C2 - 1000µF 50V
D1 - 1N4007
D2 - 1N4007
D3 - 1N4007
D4 - 1N4007
ZD1 - 16V Zener Diode
ZD2 - 16V Zener Diode
ZD3 - 12V Zener Diode

This power supply can provide output voltage 1.2V - 12 with maximal output current is 1A, low voltage LED indicator added in this schematic diagram. The indicator part includes three diodes and one LED. For example you are charging a battery, you can observe the charge status at that moment. Another advantage of this schema, when the drawn current exceeds 1A (practically 0.85A), the current protector in LM317 intervenes and LED indicator warns you about the very low output voltage.

 Simple Uninterrupted Power Supply in an IC Circuit Diagram
 

Easy-to-Use Evaluation Kits for Power Backup Applications

• CBC-EVAL-05 EnerChip CC Evaluation Kit which contains everything needed to test EnerChip 12uAh and 50uAh thin film batteries, EnerChip CC CBC3112 and CBC3150 batteries with Integrated Battery Management, and to test multiple batteries in parallel. This kit will also include a CBC3105 evaluation board for experimenting with this device.
• CBC-EVAL-06 Real-Time-Clock Evaluation Kit: includes a Microcrystal NV2123 Real-Time Clock device and a CBC3112 EnerChip CC for battery backup. This kit also includes a Windows based Graphical User Interface to set the clock & test operation in RTC back up and count-down modes.

Visit Cymbet at Design West/ESC Booth 2330 for UPS in a Chip Demos

This is an LM317 based adjustable voltage regulator with a maximum output of 3V and 1.5A. The output voltage depends on the V_IN, R1 and R2 values, so the schema can be modified to use with a maximum output of greater than 3V. The maximum current output is also independent of the schema design, it is related to the package options. In this schema, LM317T, which is capable of transferring up to 1.5A, is used.

Since the internal reference voltage of the LM317 regulator is 1.25V, the output voltage can be also minimally 1.25V. One way to overcome this problem is using a reference voltage source built on two diodes. But this approach is mostly suitable for 1.5V to 15V regulators since the sensitivity becomes poor for the low voltage outputs less than 1.5 . On the other hand, diodes have temperature dependent forward voltages.

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