finally an electrostatic transportable

[kevin gilmore]

after all these years we have finally found a solution for the power supply modules at a rational price. which means we can make a transportable electrostatic amplifier.

similar to srmxh,srm252,srm270  etc.   3 times the power, +/-400v power supplys, no obsolete components etc.  designed to be mounted to the bottom as a heatsink with silicone thermal sheet in between.  should be about $250 in parts unless you go nuts with the volume pot. not sure of casing yet.

[Kerry]

Wow, really interesting!

I’m very curious about the power supplies. 

[kevin gilmore]

all three power supplies a total of $80.62 with shipping from china.

fully regulated 12v to 18v input.

i could not build these things for that price, no way.

[Kerry]

The parts for the bias supply I can do for less, but not the 400V supplies.

This is definitely something I want to give a listen to.

Thank you  

[PretentiousFood]

Have you tried measuring the noise from V+ to V- when the pair is stacked? I ran into trouble stacking low voltage Mean-Wells in this manner; not sure if it's the slightly different oscillation frequencies from unit to unit, the stray capacitance, or something else, but it's significantly worse than when measuring a single unit.

A good workaround if this proves to be troublesome is to place a common mode filter on the output of the SMPS, and to stack the outputs of the filter rather than the SMPS V+/V- pins. This eliminated noise that differential mode filtering and regulators couldn't take out in a couple of my builds. I've found that I need a fairly large value CM choke and cap, at least 50mH for the choke and upwards 1uF for the cap. These Kemet parts have worked well for me.

That said, perhaps these don't need them at all.

[kevin gilmore]

i did some quick tests and they are pretty quiet. but i plan on doing more exact tests.  cap.inductor,cap  should be more than enough.

spec sheet seems to imply 20mhz which cant be right. will get out the spectrum analyzer to make sure.

[justin]

The output ripple voltage of a DC/DC converter is often specified at a 20 MHz frequency to provide a more comprehensive view of the high-frequency noise performance. Here's why:

1. **Switching Noise and Harmonics**: While the switching frequency of the converter might be relatively low (e.g., hundreds of kHz), the switching process generates high-frequency harmonics. These harmonics can extend well into the MHz range, and measuring at 20 MHz helps capture the impact of these high-frequency components.

2. **Measurement Standardization**: Specifying the ripple at 20 MHz has become a common industry practice. It provides a consistent benchmark for comparing the performance of different converters. It also ensures that any high-frequency noise generated by the converter is accounted for.

3. **Real-World Performance**: In real-world applications, the DC/DC converter might interact with other components that are sensitive to high-frequency noise. Measuring ripple at 20 MHz helps ensure the converter will perform well in a wide range of conditions and with various loads.

4. **Electromagnetic Interference (EMI)**: High-frequency noise can contribute to EMI problems. By specifying the ripple voltage at a higher frequency, manufacturers provide a clearer picture of potential EMI issues, which is crucial for compliance with regulatory standards.

Overall, the 20 MHz specification helps designers understand the converter's behavior across a broader spectrum of frequencies, ensuring more reliable and noise-resistant designs.

[JoaMat]

20 hours ago, kevin gilmore said:

all three power supplies a total of $80.62 with shipping from china.

fully regulated 12v to 18v input.

i could not build these things for that price, no way.

Nice, great news!

 

Did this in 2019 and it has been in sleep mode since then. Maybe UHV-POWER bricks will wake it up. Power transistors plus a few other components on one side and the rest on the other side.

[kevin gilmore]

first picture is baseline with 6db antenna 0 to 100mhz 10db/major division  10mhz per horizontal major division top line -30dbm 1 inch from power supply.

second picture is with the 600v power supply turned on and into a 1meg ohm load.

3rd picture is hall probe on the input power supply line. so 200khz flyback switching frequency.

Edited August 8 by kevin gilmore

[kevin gilmore]

pretty close to production now.