I will just explain part of this circuit. D9 and D10 provide a low cost -1.4 from -5 V. This is needed to reach near 0.00 for LM317 Min. setting. An LED also can be used with proper bias. Note that there is a Temperature Coefficient in ppm, but it may not matter upto 8 bits accuracy.
TIP2955, TIP3055 (NPN), TIP2955 (PNP) Complementary Silicon Power Transistors. It is a Darlington, that means good current gain. When current in R1 10E goes more than 50mA a voltage of 50mA X 10E = 500mV is applied across Emmiter-Base junction. So lower than 500mV no bias the tap is turned off, 500mV-700mV the tap starts turning on depending on type of transistor.
The transistor is like a water Tap. So TIP2955 carries the major current burden thru the load allowing LM317 to do the decision making when to turn-on or off. It is analog control, it is not On-Off but linear-proportional. The LM317 is very cool as the burden is passed off to TIP2955 who will need a heatsink to keep going and deliver the power you want.
Put the filter caps appropriately. The Hum-Noise will be filtered. The cap after the regulator should be a small guy. The main filter cap after the Bridge can be as big as your cabinet or budget.
If you build it and wire it without designing a PCB, then make all wiring and connection very sound. The test of this ability you can know easily, If your project stops working after the last screw of the cabinet is tightened, Then we need to improve.
The TL494 incorporates all the functions required in the construction of a pulse-width-modulation (PWM) control circuit on a single chip. Designed primarily for power-supply control, this device offers the flexibility to tailor the power-supply control circuitry to a specific application.
Uncommitted Outputs for 200-mA Sink or Source Current
Output Control Selects Single-Ended or Push-Pull Operation
Internal Circuitry Prohibits Double Pulse at Either Output
Variable Dead Time Provides Control Over Total Range
Internal Regulator Provides a Stable 5-V Reference Supply With 5% Tolerance
Circuit Architecture Allows Easy Synchronization
The TL494 contains two error amplifiers, an on-chip adjustable oscillator, a dead-time control (DTC) comparator, a pulse-steering control flip-flop, a 5-V, 5%-precision regulator, and output-control circuits.
The SG3525A pulse width modulator control circuit offers improved performance and lower external parts count when implemented for controlling all types of switching power supplies. The on-chip +5.1 V reference is trimmed to +/-1% and the error amplifier has an input common-mode voltage range that includes the reference voltage, thus eliminating the need for external divider resistors. Half Bridge, Push-Pull.
Power Supplies, Inverters, UPS, Chargers, Electro Plating, Precision Welding-erosion, Coating Metals and many other Processes are made of high current circuits. Even in measurement of parameters like Micro-Ohm high currents are involved. Electronic Circuits are required in such products to give control to time, current, frequency and voltage in order to accomplish with the required precision a process or job.
In any power equipment, efficiency and reduction of bulk is crucial so SMPS and high frequency control is an important part of this domain. These products also generate EMI-RFI. Product Safety Study is also vital.
I first saw this practically in the Orthodox Cherokee SMPS. This is where we differentiate from Engineered Products and just Mass Production without following standards. The Cherokee SMPS was a work of art, perfect in all respects.
The Copper Desert or Isolation Land
There is a No Man’s Land in PCB. Any good power electronics designer should/will know. Product Safety and HV Isolation, Quality and Reliability all depend on this.
These things don’t come overnight, it is a culture, learning, experience and integrity of some of these American Firms. Reliability and Product safety are important. Every human values his life very much. A manufacturer too should appreciate this.
Coming back to isolation, Keep in mind creepage distance, High energy circuits and Low voltage circuits should have clear isolation, use the best insulation. Fire and shock hazard. Mains HV transitions, spikes.
Uninterruptible power systems (UPS) are backup power supplies that use a built-in battery to stably supply continuous clean power to connected devices when the regular supply power shuts down due to a power failure or other power problem. TDK-Lambda offers both these types of power supplies”.
“On September 4, 2007 Murata completed its acquisition of the Power Electronics Division of C&D Technologies, making us the world’s number one supplier of DC/DC Converters and the fifth largest supplier of power overall. Going forward, the Power Electronics Division will be known as Murata Power Solutions.”
“..world-leading manufacturer of dc-dc converters, ac-dc power, military power supplies, digital panel meters, magnetics, data acquisition devices and contract electronics manufacturing (CEM) services…”
( C&D Technologies was Datel GE )
Daylight Readable and Auto-Dimming
200-2000 Watt Front-End Power Supplies
How i remember Datel was from the A/D Converters and Analog Mux they made of very low on resistance and crosstalk. It was part of GE at that time, like Intersil. I was an R&D Engineer for an Industrial Instrumentation Company. It must have been the time when 8031/51 was getting very popular.