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Voltage regulator 15V 5A Dual Supply

The fig. 6.2 shows the circuit of a regulated power supply for +/- 15 V and 5 A. The output voltages are adjustable between 12 and 17 V.

A tape-wound core transformer is used. It offers a better power-to-volume ratio than conventional ones with laminated cores. The voltage control is achieved by two series transistors, connected in parallel, and by the opamp TAA 761, which acts as control amplifier. For the negative voltage the ground potential serves as reference level for the desired-to-actual value comparison.

The voltage is adjusted by the potentiometers P1 and P2, whereby the center tap of P2 is set firstly to 0. Then both output voltages can be adjusted symmetrically through P1 (range between 12 V and 17 V, for instance).

NPN power-transistors are used as series-control components for the positive as well as negative voltage. Since two transistors 2N3055 have to be connected in parallel for each output voltage, 0.22 ohm resistors are inserted in their emitter leads to achieve a symmetrical load splitting.

Fig. 6.2

Voltage regulator 15V 5A Dual Supply

Technical data:

Mains voltage …. 220V ±15% 50Hz
Output voltages …. ±15V (adjustable from 12 to 17V)
Max. output current …. 5A each
Max. ambient temperature …. 50 deg C

Mains transformer

Tape-wound core …. 2xSE 130a
Primary windings (220 V) …. n1 = 490 turns, d = 1.0 mm o/
Secundary windings …. n2 = n3 = 50 turns, d2 = d3 = 1.8 mm o/
Ordering code …. B71725-A130-A2

Thermal resistance of heat sinks

for each transistor 2N3055 …. Rth </= 2.5 K/W
for each transistor BD234 …. Rth </= 23 K/W or
for each transistor BDX27 …. Rth </= 38 K/W

Power Supply Circuits – Voltage regulator ± 15 V/5 A
from Design Examples of Semiconductor Devices – Siemens – 1974/75

Did you know ?

Siemens Semiconductors was spun off on April 1 1999 to form a separate legal entity Infineon Technologies AG

for Information about these pages and purpose, see About Olden Circuits

Parallel Controlled Power Supply

Parallel-controlled circuits operate as self-controlled, variable resistors, connected in parallel to the load impedance (parallel loads). They react extremely fast and also control immediately pulses and very short mains break-downs, resulting from strong loads. These devices are preferably used in TV receivers, which have a B-class operated audio output stage. Without any parallel control the picture width is influenced inconveniently by the rhythm of speech and music. However not only in TV receivers a parallel control circuit is advantageous, but there are also a lot of applications requiring such a design.

The parallel control circuit can also be described as a “z-diode booster”, which offers, however, the great advantage, that the power dissipation of the control transistor can be reduced to a quart of that of a z-diode representing the same function. Thus the collector resistor can take the total parallel-load when the transistor is switched on. Supposing that half of the voltage is available at the collector, only half of the current flows through the transistor, power dissipation of which is only a quart of the total power consumption of the parallel load. The circuits 1 and 2 are proportioned for a parallel load of </= 6 W. In many cases the former is sufficient. It is characterized by a remaining control voltage of < 250 mV. The circuit no. 2 consists of two stages and improves the voltage control to about 20 to 50 mV. The small elaborateness of only one transistor and one resistor is advantageous in many cases.

fig. 6.1 and 6.1.1

Parallel Controlled Fixed Power Suppy

The circuits of fig. 6.1 and 6.1.1 are designed for fixed output voltages. The resistance of Rv is determined on the control range, on the value of the supply voltage and on its fluctuation. The maximum range of power control is determined by the resistance of Rp (control resistor).

Fig. 6.1.2 and 6.1.3

Parallel Controlled Adjustable Power Suppy

The circuits of fig. 6.1.2 and 6.1.3 are dimensioned for a power of 15 or 30 W. The output voltage is adjustable in a range of 24 to 35 V, for instance. As it can be seen the circuit of fig. 6.1.3 employs only one transistor, the Darlington-transistor BD 675.

Power Supply Circuits – Parallel-Control Circuits
from Design Examples of Semiconductor Devices – 1974/75 of Siemens – The Silicon Pioneers

for Information about these pages and purpose, see About Olden Circuits

Antenna-amplifier with BFT 12 for FM-range

The only way to improve the reception of FM-signals or particularly of stereo FM-signals under disadvantageous receiving conditions is to amplify the antenna signal. This should be made directly at the antenna, since the loss is increased meter by meter of any cable. In most cases higher line attenuations can be expected than usually calculated. Even receivers with an additional noise figure of zero do not show any improvements of the signal-to-noise ratio becomes too low because of a long transmission line. Therefore it is practically useless to require extremely low noise figures only for the receivers.

To avoid interferences of signals received from stations of other bands it is propitious to amplify the FM-band only. The band amplifier shown in Fig. 1.3 is connected directly to the 60 ohm output of the FM-antenna, i. e. it is placed at the top of the antenna pole. The matching is achieved by the input band-pass connected to the base of transistor BFT12, being a typically linear silicon transistor for broadband amplifiers. The output filter matched accordingly to a 60 ohm coaxial line is connected to the collector. The operating voltage of 15 V can be supplied by the coaxial line.

Fig. 1.3

Antenna-amplifier with BFT 12 for FM-range

Technical data:

  • Power gain Gp = 22 db
  • Noise figure F = 3.5-4.0 db or 2.2-2.5 KT0
  • Input and output reflexion coefficient |r1| and |r0| <= 0.3
  • dim(60db) at Vout = 680 mV
  • dim(50db) at Vout = 1000 mV

Optimum operating point of minimum intermodulation

Ic =~ 80 mA Vce =~ 7-7.5 V
Supply voltage 15 V

Coil data:

Vogt coil former, ordering code: Sp 3.5/16.6-2048C
Core: U17

  • L1 : 5 turns Cu 0.6 mm \o
  • L2 : 3 turns Cu 0.6 mm \o
  • L3 : 3+2 turns Cu 0.6 mm \o

Choke Ch1 = Ch2: 20 turns Cu L 0.3 mm \o, cross section of winding = 4 mm

Credits –

Antenna-amplifier with BFT 12 for FM-range
from Design Examples of Semiconductor DevicesSiemens Milestones from 150 years – 1974/75

for Information about these pages and purpose, see About Olden Circuits

Audio Hi-Fi DIY – Claudio Bonavolta

“Do-It-Yourself … That’s the choice I did and the reason you’ll find several schematics, mainly for tube electronics, but also some formulas for loudspeakers”

Audio Hi-Fi DIY – Claudio Bonavolta

Measures Conversion, Electronics, Loudspeakers, RIAA preamps, Solid state MC preamps, Solid state preamps and Solid state amps.

Audio Hi-Fi DIY - Claudio Bonavolta

(Proper Loudspeaker Design is more complex than Launching Rockets into the Ocean – Ananth)

Tapered Quarter Wave TubeFirst described by Paul Voigt in 1930, TQWTs allow a good quality-to-price ratio. They are also easy to build.Similar to transmission lines, the TQWT is different by its shape, a kind of horn is used as back load but the driver is not placed at the beginning of the cone as usual but on its side.

In closed boxes, the back wave of the speaker should be completely absorbed (= converted in heat) by the damping material.As the speaker is nearly transparent to sonic waves, if a back wave returns after a reflection on the back wall, some part will also come out through the speaker with some delay giving a not very clean sound.

PIC RISC microcontrollers – Peter Luethi

PIC RISC microcontrollers – Peter Luethi

This website provides you helpful information about Microchip PIC 8 Bit RISC microcontrollers. Several assembler source code listings are available for non-commercial use. There are also tools for using your PC for measuring or regulating electronic applications. I’am working on several projects, e.g. a precision digital altimeter to use in my radio controlled airplanes.

dot matrix LCD

Radio Controlled Modeling – RC Circuits

PIC Assembler Projects, PIC Assembler Modules, Electronic Circuits, Student Projects, R/C Modeling Circuits, Servo Checker. Projects of Peter Luethi – Switzerland.

“The current concept incorporates a wireless transmitter and receiver and is thought to be used for remote controlled airplanes or appliances with two seperate parts.”

Mike Ellis – Electronic Projects Tutorials

The Multimedia Electronic Literature & Learning Internet Site A website dedicated to the advancement of electronic engineering skills by Mike Ellis.

Mike Ellis – Electronic Projects Tutorials

 

Complete schematics and code for a 68HC11 based frequency counter, square wave synthesizer, sine wave synthesizer, programmable filter, capacitance and inductance meter, with a digitalker speech synthesizer output.

  • 68HC11 Function Generator
  • Oscilloscope Block Diagram and Schematics
  • Dual 0-15 Volt Tracking Power Supply
  • Audio Amplifier
  • On-Line Tutorials

Bill and Mark Sherman Make Robots

From Joule Thief Artbots to Picaxe Projects. Bill and Mark Sherman are Making Things that Move.

See me at Maker Faire!

Some are Mood Beam Autopsy Make an artbot out of a Mood Beam toy. FireFly Project Make a “Jar of Fireflies” using a Picaxe Microcontroller.

Bill and Mark Sherman Make Robots

Rollie front view showing heat sensor

A two wheeled robot using foam and CDs for the wheels. Shown above is the Front View, Heat Sensor, IR avoidance module and Beeper.

The latest projects are featured at The Botsmaker Blog.

(Bill and Mark, ever tried Google Sites, use it with the same Blogger/Gmail Login. See what you can do with it – Practical Electronics )