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.

Wow, really interesting!

I’m very curious about the power supplies. 

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.

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  

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.

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.

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.

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.

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, 20242 yr by kevin gilmore

pretty close to production now.

What are the differences between this and the portable electrostatic amp in the other thread? Or is this just an update thread with new power supply modules?

same push pull stacked circuit with higher voltage all smd parts.

also this

https://buyee.jp/item/yahoo/auction/d1165787088

ac powered version of stax d10 with the lower voltage apex parts.

On 12/27/2024 at 11:20 AM, kevin gilmore said:

same push pull stacked circuit with higher voltage all smd parts.

also this

https://buyee.jp/item/yahoo/auction/d1165787088

ac powered version of stax d10 with the lower voltage apex parts.

This apex chips has no any radiators - very poor design.

you are not looking carefully enough.

there is much more wrong with this thing. hint: power supply

Plus it has Apex chips in general so it is awful. 

well there are apex chips that do sound good. but they are stupid pricy. and require large heat sinks.

someone asked for this, so here is the amp board.  working on power supply board now

need to find a suitable chassis. power supply board in progress.

cfaelectrostatschem2-4 - CADCAM.ZIP

 

cfaelectrostatschem2-3.PDF

cfaelectrostatschem2-3ps - CADCAM.ZIP

Edited January 12, 20251 yr by kevin gilmore

On 1/12/2025 at 2:05 PM, kevin gilmore said:

someone asked for this, so here is the amp board.  working on power supply board now

need to find a suitable chassis. power supply board in progress

 

Kevin, not to urge you, has there been some development?

I'd like to try a build of this, but that DC DC converters you linked are now nowhere tbf, or out of stock at least.

There are always that cheap chinese smps flybacks, very small money, and a louzy ripple characteristic.

Would be interesting to know how they did the V multiplier on their SRM D10.

What is the current draw of the amp part?

 

🙏 Thanks!

Only a few years yet As I remember this is a two decades project.

To be powerful enough to drive an sr-007, min 10 hours battery time, portable, diy-able, affordable ...  Too hard.

 

there is an american manufacturer of the same power supplies, same foot print. about double the price. don't remember where.

i have too many new toys to play with at the moment.  one makes 116db on startup. its pissing off the neighbors. (which is a good thing)

High octane not high voltage.

 

https://shop.analogtechnologies.com/ATMV12V400V10MA1.htm

Here's a similar American manufactured PSU. Unfortunately it's only 10ma of current instead of 20ma

On 2/20/2025 at 9:33 AM, Michelag said:

Kevin, not to urge you, has there been some development?

I'd like to try a build of this, but that DC DC converters you linked are now nowhere tbf, or out of stock at least.

There are always that cheap chinese smps flybacks, very small money, and a louzy ripple characteristic.

Would be interesting to know how they did the V multiplier on their SRM D10.

What is the current draw of the amp part?

 

🙏 Thanks!

You can buy them on Taobao here: https://item.taobao.com/item.htm?ft=t&id=694554929492

updated board file, 10k input resistors added (optional) and 25k changed to 17k

 

cfaelectrostatschem2-4 - CADCAM.ZIP

17k smd resistors are quite hard to find. Would you recommend 20k or 15k ohm resistors?