Electronics > Projects, Designs, and Technical Stuff
Open HV Probe 40kV
beanflying:
Reason HV probes are either rubbish from the usual asian suspects or what I consider way OTT on price for what little they contain.
While this is starting out as a 3D Print type of project the options for what goes inside and what you use the enclosure for can be far more wide ranging. The design is optimised to avoid needing supports when printed is the main reason for so many parts.
Currently I am printing the first sample one and tweaking the design as I go but as you see it is a close clone the Pintek and some others on the commercial market.
Version 1: 40kV maximum rated 990Mohm divider against a 10Mohm Meter for a 100:1 divider. Plan is to make up the 990 MOhm Resistor with 500, 400 & 90 MOhm Ohmite Slimmox 1% https://au.mouser.com/datasheet/2/303/res_slimmox-1265542.pdf . Fairly easy to change around from that if you want but the three of them will fit in the long tip barrel easily attached to a 5mm knurl nut in the final tip section to screw the metal probe into. These three cost circa $22 USD from Mouser so add that to a few other bits and for around $40-50 you will have a 1% 40kV HV Probe.
Version 2: Something in a lower kV rating but with far better bandwidth for possible Scope use.? Thinking circa 2-3kV and 1-2MHz? Totally open to circuit options and ideas and I have added a slotted mount into the handle to take a 20x80x1.6mm PCB.
Version 3: Chicken Stick for playing with Neon and MOT Transformers just because it's fun and it should be safe fun lest your internal smoke come out.
Version X: Up to you lot. Possible self contained probe like the older Heathkit one with a built in meter in the handle?
When I have a print that works and screws together I will drop the STL's here for others to try out most likely later today as I am onto the 2nd Red barrel section already and so far so good.
tggzzz:
What material are you using?
Is it in any way hygroscopic over time?
Can oils/grease/etc lodge on the surface and be difficult to remove?
At 40kV it might be necessary to be careful of those points, but those questions are worth what you pai for them.
beanflying:
--- Quote from: tggzzz on April 21, 2019, 05:54:51 am ---What material are you using?
Is it in any way hygroscopic over time?
Can oils/grease/etc lodge on the surface and be difficult to remove?
At 40kV it might be necessary to be careful of those points, but those questions are worth what you pai for them.
--- End quote ---
True of fairly much all plastics and especially with HV. Regardless of commercial or home made care with oils and water is a must do. I am planning to use PLA on mine but ABS would be fine too, PETG I have never seen any tests done on it but it is better with moisture then PLA for example but I am uncertain of it's electrical characteristics.
The couple of youtube videos below are worth a look. There is also some on Lichtenberg Figures and dumbasses with MOT's but playing with salt water and HV is DUMB if you don't know what you are doing. :horse:
With Version 1 for example if used properly your hand will be 60+mm away from an Earth referenced point and further away than that to any HV so unless you are being rained on with salt water fairly safe.
Long term keep it clean and dry and if in doubt print another.
https://youtu.be/-_LJXKLgIYc
https://youtu.be/ZqXQRq8As1o
tggzzz:
--- Quote from: beanflying on April 21, 2019, 06:11:55 am ---
--- Quote from: tggzzz on April 21, 2019, 05:54:51 am ---What material are you using?
Is it in any way hygroscopic over time?
Can oils/grease/etc lodge on the surface and be difficult to remove?
At 40kV it might be necessary to be careful of those points, but those questions are worth what you pai for them.
--- End quote ---
True of fairly much all plastics and especially with HV. Regardless of commercial or home made care with oils and water is a must do. I am planning to use PLA on mine but ABS would be fine too, PETG I have never seen any tests done on it but it is better with moisture then PLA for example but I am uncertain of it's electrical characteristics.
--- End quote ---
The fabrication technique may also be relevant, in particular the body will not be smooth and will not be solid. Both of those may trap undesirable water/oil/etc.
--- Quote ---Long term keep it clean and dry and if in doubt print another.
--- End quote ---
I always have doubt, so that wouldn't help me!
Sorry, I don't feel like spending 40 minutes of my remaining life looking at those videos. (Especially since almost all yootoob vids are talking heads and I can speed read much faster than I can watch videos)
tggzzz:
For comparison, here's my 40kV meter. Tip to disc is 13cm, disc diameter is 7cm
I picked it up cheaply, and haven't had occasion to use it at more than a too small fraction of its rated value.
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