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.
Power Supplies Section
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.
Mains Voltage Power Transformers
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.
PWM Control Circuit – TL494
- Complete PWM Power-Control Circuitry
- 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.
TL494 Related Links
SG2525 – SG3525 – PWM SMPS Regulator Chip. A second generation ic switch mode controller optimized for high frequency.
100kHz Half Bridge Convertor – SG3525
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.
SG3525 usage in SMPS 500W – It was used in Parallel for Electroplating with a central Load sharing control between modules.
- 8.0 V to 35 V Operation
- 5.1 V +/- 1.0% Trimmed Reference
- 100 Hz to 400 kHz Oscillator Range
- Separate Oscillator Sync Pin
- Adjustable Deadtime Control
- Input Undervoltage Lockout
- Latching PWM to Prevent Multiple Pulses
- Pulse-by-Pulse Shutdown
- Dual Source/Sink Outputs: +/- 400 mA Peak
Here are power supply, inverter, drives, chargers and high current equipment diagrams and links. There are Mosfet and Thyristor circuits too.
Power Electronics Section
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.
The Power Circuits Section has been updated.
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.
High Energy Circuits
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.
Regulated High Voltage Power Supply
Power supply faces all these, even other areas where a Human Life or Property can be endangered.
HV High Voltage Reliability and Safety
Use a Servo Stabilizer or CVT Constant Voltage Transformer or at least an Isolation Transformer. The First Defense form HV Surges, Spikes.
High Voltage Polyester & Polypropylene Metallized Capacitors in Stepdown Supplies should be Fire Retardant & Self Healing with a MOV too.
Switching power supplies are power supplies switched by high-speed semiconductor switches. They are the most common type of compact, lightweight, high-efficiency power supply.
TDK Lambda – SMPS UPS Power Supply Specialist
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”.
CME150-24 – Single output AC-DC converter 150 – TDK Lambda
Output voltage of 24V at Max output current of 6.3A and Efficiency of 82%
- Leakage current 0.3mA or less (at 265VAC)
- Medical safety standard (IEC60601-1) approved.
- Max output power 151.2W
- Input voltage range AC 85 – 265 V
- Input voltage range DC 120 – 370 V
- Input frequency 47 – 63 Hz
Murata Power Solutions – DC-DC Converters
“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 )
- Process Monitors
- Daylight Readable and Auto-Dimming
- Digital-to-Analog Converters
- 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.