Recent Posts

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21
Pekka asked me to start a thread about hall effect sensors and their use on measuring current.

Well, these sensors can be used to measure current. Actually they do not measure electrical current but the magnetic field that the current creates.

If You pass current through a wire there is a magnetic field created around the wire in 90 degree angle to the direction of the current. If it is a wire then the magnetic field takes a cylinder form around the wire.

In order to measure this magnetic field the sensor has to be in 90 degree angle with the magnetic field to be measure so that the magnetic field goes through the sensor.

Luckily the hall effect sensors are quite small so placing those nearby the wire might give acceptable result.

However, the magnetic field is rather weak as compared to the sensitivity of the sensor. To overcome this issue a concentrator can be used. Basically it is tube made of some ferromagnetic materiall having a slot on one side. The sensor is then placed in that slot.

I have made a solar panel current sensing equipment for 12 solar panels where the current of each panel was measured separately. Ended up using hall effect sensors with concentrators made from mild steel tube. These sensors were then equipped with microcontrollers and finally all of the communicated with a master device using I2C.

Sensor data sheet

22
Project Logs / Re: Building a New Lathe
« Last post by awemawson on May 22, 2018, 03:59:32 AM »
. . . just sometimes all the stars line up, and things work out well  :clap:
23
Resources / Re: Photobucket
« Last post by vtsteam on May 21, 2018, 09:47:59 PM »
Took mine off and hosted them myself, a major effort to rewrite maybe a thousand links. Naturally won't be re-posting them there.  :loco:
24
Gallery / Re: Lidar Build
« Last post by Brass_Machine on May 21, 2018, 08:51:07 PM »
All I can say is . . . . . AMAZING . . . :thumbup:

Agreed. That is pretty cool.
25
Project Logs / Re: my way to billd a stuart 10 horizontal engine
« Last post by krv3000 on May 21, 2018, 08:29:02 PM »
lol well every thing is on hold me work bench is full of er tools I put a bid in for a wooden tool box witch is full of tooling did not think I wood win it till I got a txt saying I had won and it was just up the road lol as like a kid at xmas will post pics tomorrow
 :drool:
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Project Logs / Re: Building a New Lathe
« Last post by vtsteam on May 21, 2018, 08:02:38 PM »
I stopped down at Lester's old time machine shop. Found Lester in the back and we jawed for a half hour or so. Eventually I mentioned I wanted some hot rolled 1-1/4" round stock to make a boring bar, and my tailstock ram with. I'm using a tailstock casting that I bought from Ebay for a Craftsman lathe. Lester said why didn't I want cold rolled? I said well the bore is actually 1-1/8" and I'm not sure how worn it is, might need to turn it to an odd dimension, etc.

He said, well, I have some 1-1/8 cold rolled. Had it for a long while. I don't use it much. Okay I said, I'll take about three feet of both, then, just in case. So he cut me the hot rolled bar, and hunted up the cold rolled, which was on a shelf in an ancient cardboard tube, that just fit it. When he pulled the bar out, it was just under 3 feet, so I said that was fine. He charged me $22, and I could probably make six tailstock rams with that if I wanted to. He gave me the cardboard tube, too.

Well when I got it home, it was all coated up with sticky preservative stuff. I cut off 7" of it and cleaned it up with kerosene. Imagine my surprise when I saw it was ground polished stock! And the fit in the tailstock was absolutely perfect. perfect sliding fit. Like they were ground for each other.

So I guess I lucked out on that one. Maybe that's why it was in that protective cardboard tube. Thank you Lester!

The ram blank in the tailstock:



27
Resources / Re: Photobucket
« Last post by philf on May 21, 2018, 06:49:33 PM »
I agree Andrew - I spent ages moving mine to another host (who doesn't charge anything - thank you friend if you see this!) and I won't be going back.

Phil.
28
Resources / Re: Photobucket
« Last post by awemawson on May 21, 2018, 06:41:47 PM »
Too late I'm afraid, they've shot their bolt as far as I'm concerned, I'll never trust them again.

The leopard doesn't change its spots , once a blackmailer always a blackmailer !
29
Resources / Photobucket
« Last post by philf on May 21, 2018, 06:11:40 PM »
I've just had an email from Photobucket who are now under new management.

"Hello,

All of your hosted images across the internet have been restored for a limited time under your Free Account.

We are also offering a new, competitive subscription package that includes:

Continued use of 3rd Party Image Hosting services
10GB of Storage
 No Advertisements
All of this for just $1.99 per month or an option of $19.99 per year. 

Hurry, last day for this offer!  Prices increase to $2.49 per month or $26.99 per year on May 22nd, 2018!
"

A bit late now but much cheaper than their previous offer.
30
Gallery / Re: Lidar Build
« Last post by awemawson on May 21, 2018, 05:39:27 PM »
All I can say is . . . . . AMAZING . . . :thumbup:

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