HV power supply help

[WrineX]

i use these for the regulation

Jtron DC 4.5~35V to 1.25~30V Adjustable Voltage Step Down Module - Red - Worldwide Free Shipping - DX

very cheap and nice, with pot.

and for inverter i use these

https://www.conrad.nl/nl/koude-kath...00-mm-groen-conrad-inhoud-1-stuks-720375.html


you get the tube and inverter. i do must say i had a version of 600 volt and one 700 volt , so not exactly the same. and they where even cheaper to. the inverter was in a blue plastic housing witch is nice

 

[kffern]

inverters

Searching again I've come up with quite a variety.
I didn't think they would go over 240V. This claims 900V!
http://www.ebay.com/itm/Spare-Inver...-Rings-Kit-4-outputs-12V-Female-/111315870578
This looks good too but no details.
https://www.ple.com.au/Products/618703/Bitspower-CCFL-Inverter-Kit

In case anyone is interested in the HV probe I have, I hand drew the circuit. PM me if you need any more info.

An externally hosted image should be here but it was not working when we last tested it.

kffern

 

[bolserst]

Bought a new meter yesterday…Tried it on one PS and it seemed Ok but will try again when I get back home tonight.

Sound like you are back in business.
Will wait to hear how measurements go with it on your inverter/multiplier combination.

The listing for your meter doesn’t specifically say it has 10Mohm input resistance.
Does the owner’s manual mention what is is?
10Mohm is pretty much the standard for DMMs, so probably not an issue.

When measuring the output of the inverter I used the Fluke which started around 200V and slowly built up to 250-260V AC. My other (now expired) meter would not read anything. When I used the HV probe with the Fluke (on a working HVPS) it measured much lower than the now dead meter. I mainly used the old Micron with the HV probe.

Since most CCFL inverters run at frequencies in the 20kHz to 40kHz range it is possible that your older Micron meter could not process an AC voltage reading for that high a frequency, but the Fluke could. Another less likely possibility is that the inverter needs a minimum load to operate which the Fluke 7-600 with its low input impedance provided.

You can test the frequency response of your DMM by feeding it 1Vrms from a signal generator and seeing how the reading changes relative to 50-60hz as the frequency is varied. Response of many DMMs take a nose dive above 1kHz. Some newer DMMs I have tested hold up pretty well to 10kHz.

BTW, rather than trying to measure AC voltage output from the inverter, you can just add a single diode and capacitor to the output and measure the DC voltage across the capacitor with your HV probe.

I used IN4007 diodes and 0.01uF/3KV caps.

The reverse recovery time for the 1N4007 diodes is adequate for use with 20kHz to 40kHz inverters.
But, if you start running higher frequencies and/or higher current application then it's a good idea to use diodes designed with faster switching times as geraldfryjr mentioned. Actually, there is not much difference in cost between 1N4007 and UF4007 1kV rectifier diode so I usually just get the UF4007. In fact, sometimes the UF4007 is cheaper.

Some O-scope captured data on diode turn on/off times here if interested.
Diode Turn-On Time

Searching again I've come up with quite a variety.
I didn't think they would go over 240V. This claims 900V!

CCFL Inverters are available in a broad range of voltage and current outputs…recently I’ve seen as high as 2kV.
Inverters | Optoelectronics | DigiKey

I continue to be happy with the lower current TDK modules. http://www.diyaudio.com/forums/planars-exotics/190716-esl-power-supply-question-5.html#post3714088
Be sure to hook up your multiplier upstream of the current limiting capacitor included inline with the secondary of most CCFL inverters.

 

[geraldfryjr]

kffern, On your drawn schematic you have to include your DMM's input resistance that is in parallel with the bottom resistors to be able to calculate your actual division ratio.

This is why I use a High input impedance Unity gain buffer in order to isolate the DMM's input resistance from the Voltage dividers output.

Some of my DMM's have a high impedance but some of my cheapy DMM's are only about 20Kohms or so.

jer

 

[kffern]

Thanks bolserst and Jer for your continued help. I have been either busy or tired after work to do much. Wife doesn't like me being in the garage at night as well.

The listing for your meter doesn’t specifically say it has 10Mohm input resistance.
Does the owner’s manual mention what is is?
10Mohm is pretty much the standard for DMMs, so probably not an issue.

It doesnt say but one of the others I downloaded do so assume they all do.
The probe instructions say the meter should be 1000VDC capable but the one I bought is 600V. Duh! it was a rushed lunch hour purchase and the range muddled me up. I'm torn between buying the cheap Q1053A or the one I should have plunked down for at the start Q1134. The Q1053A should be fine...penny wise and pound foolish.

The reverse recovery time for the 1N4007 diodes is adequate for use with 20kHz to 40kHz inverters.
But, if you start running higher frequencies and/or higher current application then it's a good idea to use diodes designed with faster switching times as geraldfryjr mentioned. Actually, there is not much difference in cost between 1N4007 and UF4007 1kV rectifier diode so I usually just get the UF4007. In fact, sometimes the UF4007 is cheaper. .

I have ordered some UF4007 diodes as they are not available at Altronics.

Be sure to hook up your multiplier upstream of the current limiting capacitor included inline with the secondary of most CCFL inverters.

Didnt know that!
Thanks again,
kffern

 

[kffern]

I have finally sorted it out!!

The new meter actually does work but wants the DC V select at 200.

I read the correct multiples of V at each diode pair.

As for the old meter, it might just be the fuse. Since the continuity check worked when I touched the leads together and the display was dead I assumed I had blown something on the board. Will replace and hope for the best. Its nice working with something you are comfortable with.

I will order some of those DC boards and one of the inverters and make new adjustable supplies for the Kingsound as well. They have a 7809 IC with a 12V input so I can't figure out what the trimmer is meant to do. Some of the boards look a bit melted as if they have been cleaned in solvent. The bass panel supplies range from 5.0 to 6.5 KV and it would be good to set it to as much as it take.

Thanks for all the help,
kffern

 

[kffern]

Surface resistance meter

I have just bought one of these - Surface resistance meter

Surface Resistance Resistivity Meter Electrostatic Static Electricity Tester ESD | eBay

I saw Rob had a couple and didn't realise they were so cheap. I'll let you know if they work.
kffern

 

[geraldfryjr]

Awesome !!!
I am glad you got it working !!

jer

 

[bentoronto]

Although kffern replied to my earlier post with a discourteous and denigrating response ("Thanks Ben, but yet again you type before you read"), I think the upshot of this thread has shown that it is correct for me to repeat the mild and cautious caution I originally offered, "the goof you are making should be a wake-up call that you may be short on the electrical background needed to proceed safely".

Knowing how to set the scale on your voltmeter and use the HV appliance may be just indicative of other lapses to come.

Ben

 

[kffern]

Although kffern replied to my earlier post with a discourteous and denigrating response ("Thanks Ben, but yet again you type before you read"), I think the upshot of this thread has shown that it is correct for me to repeat the mild and cautious caution I originally offered, "the goof you are making should be a wake-up call that you may be short on the electrical background needed to proceed safely".

Knowing how to set the scale on your voltmeter and use the HV appliance may be just indicative of other lapses to come.

Ben

You don't give up, do you?

It turns out the new voltmeter I bought doesn't work on the 600V DC setting. I'll be returning it tomorrow.
Changing the fuse didn't help the old meter.

In case anyone uses the variable DC kit I bought from Altronics, don't use a wallwart of more than 300mA. The caps get pretty hot. I was using a 500mA wallwart on the bench. I have a few of the ones Wrinex recommended on order.

Regards,
kffern

 

[bentoronto]

In case anyone uses the variable DC kit I bought from Altronics, don't use a wallwart of more than 300mA.

I'm using a similar 0-15vdc eBay power supply with a voltage read-out to drive an EMCO HV sealed 10kV box. One great advantage is that the EMCO HV output is closely linear with the input and so you have a good notion of the output by looking at the read-out.... from a distance.

But cost even second-hand on eBay is a disadvantage.

Ben