ATX Power Supply modified Tube Amplifier 700V SMPS

I have made various modifications on computer power supplies, I shared most of them, and some of them were left unfinished. There are so many options to try, especially by changing the transformer (ei33) windings used, the voltage limit can be exceeded as in this application, an old p3 atx power supply was modified and 700 volts 125 watts output was checked. integrated classic TL494

CAUTION The circuit is working with high voltage. Be careful with the capacitor connections. If you connect the + – poles reversely, there may be big explosions at high voltage.

Regulated High Voltage Source for Lamp Amplifiers

Replacing a PC power supply for high voltage 700V or 400V.

Completed prototype, highlighting the structure of the output filter (L4 & C9). The positive lead is passed through a small toroid 5-6 times before being soldered behind the output terminal. The capacitor is soldered directly over the positive and negative terminals as shown.

Tube amp circuits aren’t dead yet. While transistors are undoubtedly superior in most applications, the Lamp still offers many unique advantages. This applies above all to its use in power circuits.

In high-end audio amplifiers, especially in the power output stages, there is an important view that lamps outperform transistors. The seriousness of these claims is reflected in the fact that some very reputable manufacturers offer valve amplifiers at the top of the audio range.

A decent quality tube amplifier for amateurs can be made for a modest expense using designs freely available on the Internet. These amplifiers are usually based on an EL34 or KT88 lamp pair in the output stage.

700v SMPS Circuit Diagram

Another common application for lamps is in the output stages of RF power amplifiers. It will operate satisfactorily at frequencies up to about 30MHz, emitting up to 50W per lamp. Their main advantage over RF power transistors is that, in addition to being slightly cheaper, they are more tolerant to fault conditions.

When tuning a new power amplifier design, parasitic oscillations are encountered that can easily destroy expensive RF power transistors.

Although lamps are readily available, one of the main problems in their use is the lack of suitable power supply transformers. Both the EL34 and KT88 are rated at 800V maximum plate voltage with the supply voltage around 500-600V required to achieve maximum power and linearity. However, the only high-voltage power transformers currently available are isolation transformers delivering 240 V and magnetron transformers from microwave ovens delivering 1500 V or more.

Obviously, neither of these are suitable for our application.

The easiest way to do this is to replace the power supply of a personal computer (PC). The old AT power supplies are readily available and have now become a plus item. It is designed to generate about 200-300W for our application. It contains almost all the components we need for a low cost ready PC board and HV switching power supply.

Also, due to its high operating frequency, the switch mode power supply offers much better regulation and far less ripple than can be obtained from a conventional tube amp power supply based on 50Hz AC rectification and smoothing.

Tube Amplifier Swicth Mode Power Supply

Source: http://www.siliconchip.com.au/cms/A_102096/article.html

ATX modified Tube Amplifier Swicth Mode Power Supply schematic, info alternative link: