     Welding inverter is an alternative to a conventional welding transformer. Modern semiconductors allow to replace the traditional mains transformer with a switching power supply, which is much lighter, smaller and allows easy current adjustment via a potentiometer. The advantege is also that the output current is DC. DC current is less dangerous than AC and prevents arc extinction.

     For this inverter i chose topology, which is the most common in welding inverters - forward converter with two switches. In my article about switchning supplies it is a topology II.D. Input mains voltage passes through an EMI filter and is smoothed with high capacity capacitors. Since the inrush current of those capacitors would be too high, there's a softstart circuit. After switching ON, the primary smoothing capacitors are charging via resistors, which are later bypassed by the contact of a relay. As power switches, IGBT transistors IRG4PC40W are used. They are driven through a forward gate-drive transformer TR2 and shaping circuits with BC327 PNP transistors. The control integrated circuit is UC3844. It's similar to UC3842, but it has its pulse-width limited to 50%. Working frequency is 42kHz. Control circuit is powered by an auxiliary power supply of 17V. Current feedback, due to high currents, is using a current transformer Tr3. Voltage drop accros the sensing resistor 4R7/2W is approximately proportional to the output current. Output current can be controlled by potentiometer P1, which determines the threshold of the current feedback. Threshold voltage of the pin 3 of UC3844 (current sensing) is 1V.

     Power semiconductors require cooling. Most of the heat is dissipated in output diodes. Upper diode, consisting of 2x DSEI60-06A, must in worst case handle the average current of 50A and the dissipation of 80W (total of both diodes). Lower diode STTH200L06TV1 (doube diode package with both internal diodes connected in parallel) must in worst case handle an average current of 100A and the dissipation of nearly 120W. Maximum total dissipation of the secondary rectifier is 140W. The heatsink must be able to handle it. To the thermal resistance you must include the junction-case Rth, case-sink Rth and sink-ambient Rth. DSEI60-06A diodes don't have insulation pads and the cathode is connected to the the heatsink. Output choke L1 is therefore in the negative rail. It is advantageous because in this configuration, there's no high-frequency voltage on the heatsink. You can use another type of diodes, for example a parallel combination of a sufficient number of the most accessible diodes, such as MUR1560 or FES16JT. Note that the maximum average current of the lower diode is twice the current of the upper diode. Calculation of the power dissipation of the IGBTs is more complicated because in addition to conductive losses there are also switching losses. Loss of each transistor is up to about 50W. It is also necessary to cool the reset diodes UG5JT and the mains bridge rectifier. The power dissipation of the reset diodes depends on the construction of Tr1 (inductance, stray inductance), but is much lower than the dissipation of the IGBTs. The rectifier bridge has a power dissipation of up to about 30W. UG5JT diodes and the rectifying bridge are placed on the same heatsink as the IGBTs. UG5JT diodes also can be replaced with MUR1560 or FES16JT or other ultrafast diodes. During construction it is also necessary to decide the maximum loading factor of the welding inverter, and accordingly select size of heatsinks, winding gauges and so on. It is also good to add a fan.

     Switching transformer Tr1 is wound on two ferrite EE cores, each with a central column cross section 16x20mm. The total cross section is therefore 16x40mm, the core must have no air gap. 20 turns primary winding is wound using 14 wires of a 0.5 mm diamater. It would be better to use 20 wires, but they didn't fit into my core. Secondary winding has 6 turns of a copper strip (36 x 0.5 mm). Forward gate-drive transformer Tr2 is made with an emphasis on low stray inductance. It is trifillary wound, using three twisted insulated wires of 0.3 mm diameter, and all the windings have 14 turns. Core is made of material H22, middle column has a diameter of 16mm, with no gaps. Current sensing transformer Tr3 is made from an EMI suppression choke on a toroidal core. The original winding with 75 turns of 0.4 mm wire works as a secondary. Primary has just 1 turn. Polarity of all the transformer windings must be kept (see dots in schematic)! L1 inductor has a ferrite EE core, middle column has cross section 16x20mm. It has 11 turns of a copper strip (36 x 0.5mm) and the total air gap in the magnetic circuit is 10mm. Its inductance is cca 12uH.

     The auxiliary 17V switching power supply, including Tr4, is described in more detail here. The simplest welding inverter on Pic 1 has no voltage feedback. Voltage feedback does not affect the welding, but affects the power consumption and heat losses in the idle state. Without the output voltage feedback there is quite high output voltage (approximately 100V) and the PWM controller ia running at its max duty cycle, thereby increasing the power consumption and heating of components. Therefore, it is better to implement the voltage feedback. You can inspire on Pic 2. The feedback can be connected directly because the controll circuit is isolated from mains. The reference voltage is 2.5V. Select the R2 to set the open circuit voltage. You can find useful info in datasheet of UC3842, 3843, 3844, 3845 or in its another datasheet. Inspiration for modifications you can also find in 3-60V 40A supply.

     Interesting links from which I drew:
http://svarbazar.cz/phprs/index.php?akce=souvis&tagid=3
http://leo.wsinf.edu.pl/~leszek/spawarki/
http://www.y-u-r.narod.ru/Svark/svark.htm
http://www.emil.matei.ro/weldinv3.php
http://nexor.electrik.org/svarka/barmaley/kosoy/shema.gif and a little modified: http://nexor.electrik.org/svarka/barmaley/kosoy1/shema.gif

Hdsexpositive | ((link))

11. I am doing the work that works for me. 12. I am good and getting better. The Good Trade How to develop considerable ingenuity in your write-ups 30 Mar 2026 —

In the context of the Huntington's Disease (HD) community, refers to individuals who carry the genetic mutation for the disease but may not yet show physical symptoms. A post for this community typically focuses on advocacy, support, and hope for the future. Below are three post options tailored for different goals: Option 1: Community Support (Instagram/Facebook) Focus: Connection and shared experience.

While "hdsexpositive" offers a compelling vision, it is not without its challenges and critics. A truly honest article must address these complexities.

Integrating physical fitness and mental health into sexual vitality. hdsexpositive

100 Positive Affirmations for Better Self-Care - Crisis Text Line

At its core, is an approach that views sexuality as a natural, healthy, and positive part of human life. The "HD" can be interpreted as High Definition—implying a clearer, more nuanced, and detailed view of sex that moves beyond archaic, restrictive, or shame-based perspectives.

One evening, while examining a crack in her studio wall, she handed him a brush. “Here,” she said. “Don’t think. Just add something.” I am good and getting better

"hdsexpositive" is more than a keyword—it is a developing cultural philosophy for the 21st century. It challenges us to ask critical questions. Can we build a digital sexual landscape that is as ethical as it is exciting? Can HD technology, so often used for objectification, be repurposed for authentic celebration?

While "hdsexpositive" is not a standard medical or psychological term, it likely refers to the intersection of and sex positivity . Navigating intimacy and sexual health is a vital but often overlooked aspect of living with HD or caring for someone with the condition. Understanding the Intersection

In the evolving landscape of digital culture, social media hashtags frequently transition from simple sorting tools into powerful catalysts for social change. One such marker gaining significant traction across adult education spaces, wellness forums, and progressive social communities is (High-Definition Sex-Positive). Below are three post options tailored for different

“I’m here because my life is a restored Victorian,” he said, the words clumsy but true. “It’s structurally sound. The woodwork is beautiful. But I’ve been so busy maintaining the facade, I forgot to live in it. You made me want to throw a party in the parlor. Maybe paint a wall purple.”

Over time, the philosophy has broadened. Today, the sex-positive movement is a social and philosophical movement that seeks to change cultural attitudes and norms around sexuality. Its core principles are:

High-definition technology—ranging from 4K to 8K—has revolutionized how we see the human body on screen. Advanced production techniques, 4K cameras, and superior lighting capture every detail: the texture of skin, the subtlety of a blush, the authentic reactions of performers.

At the heart of any sex-positive framework is enthusiastic, uncoerced consent. In HD sex-positive media, consent is not just implied; it is often explicitly highlighted. Production companies and independent creators operating under this banner prioritize fair wages, legal compliance, and the psychological and physical safety of everyone involved. 2. Inclusivity and Representation