Racemaniac's postbag

Tell us about the cool things you've recently got
racemaniac
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Re: Racemaniac's postbag

Postby racemaniac » Wed Feb 22, 2017 12:09 pm

continuing the meter saga: i also bought a basic UNI-T clamp meter: https://www.aliexpress.com/item/UNI-T-U ... 77740.html

As mentioned somewhere else, i'm building a simple spotwelder from an old microwave transformer. seemed like a good moment to buy one of these so i can actually see the current it'll be able to generate :).

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RogerClark
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Re: Racemaniac's postbag

Postby RogerClark » Wed Feb 22, 2017 9:12 pm

racemaniac wrote:continuing the meter saga: i also bought a basic UNI-T clamp meter: https://www.aliexpress.com/item/UNI-T-U ... 77740.html

As mentioned somewhere else, i'm building a simple spotwelder from an old microwave transformer. seemed like a good moment to buy one of these so i can actually see the current it'll be able to generate :).



I have a UniT current clamp, but I think its the previous model, as I dont think mine has capacitance measurement.

I bought it to measure current from solar panels, (DC) and also to measure AC mains current, and it works quite well.

Its not as accurate as putting a meter in series with the wire, but its probably as good as you can get by using a clamp.

TomaTLAB
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Location: Moscow, Russia

Re: Racemaniac's postbag

Postby TomaTLAB » Sat Feb 25, 2017 12:51 pm

RogerClark wrote:...
I just looked and one, and its either

Brown, Brown, Black, Black, Red

Or

Red, Black, Black, Brown Brown

...


I never saw 2% resistors. Very much rare thing. :) Umm... Saw, but it were very special resistors with hand-written marking...
Therefore, with high probability, it is possible to assume that it is 1% 2k.
The much bigger problem to distinguish 110 and 1k (120 and 10k and so on).

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RogerClark
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Re: Racemaniac's postbag

Postby RogerClark » Sat Feb 25, 2017 8:33 pm

All the resistors I got in a assorted values pack from china were the old 3 band resistors, and all the ones from the local shop are 4 band, and I have loads of resistors dating back 10 to 20 years old which I am loathed to throw away as there is nothing wrong with them.

TomaTLAB
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Re: Racemaniac's postbag

Postby TomaTLAB » Sun Feb 26, 2017 11:03 pm

Pff... 20-years resistors - so young ones :D I have somewhere in a "long term storage" some pack of the resistors with flat strip wires from 60...70's, which my father used in a "warm vacuum tube" amplifiers. :D
So. If we are talk about resistors, some words about potentiometers. I'm now converting chinese motorized ball valves to the some sort of "servo-valve".
I have faced such problem: I try to use RK097N potmeter, but it have a big huge mechanical backlash between wiper and shaft! And I had to return to use of usual WH148 potmeters. Now I'm waiting for delivery of SV01A103AEA01R00. It maybe idealy fit into valve gearbox.

RK097N Image WH148 Image

racemaniac
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Re: Racemaniac's postbag

Postby racemaniac » Mon Mar 06, 2017 11:54 am

My loot for today:
- a nextion display to experiment with
- some SSR's, rated at 50A, i opened one up, it has a triac in there that should be able to handle 25A, more than i expected for 3€ SSR's ^^ (i knew i wasn't gonna get something that could handle 50A :p). i'm expecting what i'm making to maybe draw 10A, so should be sufficient :).
- one of the digital calipers, have yet to check how much current it draws in standby (usually way too much i hear)
- a raspberry pi camera
- some smd mosfets: https://www.aliexpress.com/item/100pcs- ... 72391.html

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RogerClark
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Re: Racemaniac's postbag

Postby RogerClark » Mon Mar 06, 2017 8:37 pm

Interesting about the SSRs, I have 2 of them but never used them.

The Variable SSRs are also interesting, but I dont have any because of the price.

racemaniac
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Re: Racemaniac's postbag

Postby racemaniac » Tue Mar 07, 2017 9:08 pm

more fun loot today
after begin stuck with the customs for too long: https://www.kickstarter.com/projects/11 ... ing-bricks
my first kickstarter i backed that arrived XD
i've got a lot of nice lego, and that's one of the few things i've seen in a long time that actually adds something new and creative to lego :). will have to make some time to experiment using it in making fun lego robots :D.

and what also arrived: https://www.silhouetteamerica.com/shop/ ... s/portrait
What got this to my attention: when reading pcb forums, i came across multiple threads of people using them for making pcb stencils. it's a very affordable machine, and i see people even getting good results on qfn packages with 0.5mm spacing. and besides that it's also just a cool machine to do other fun/creative stuff with :). couldn't resist :D

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RogerClark
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Re: Racemaniac's postbag

Postby RogerClark » Tue Mar 07, 2017 10:54 pm

What is the process for using that stencil cutter ?

Do you use UV resist coated boards?

I'm not sure how that is better than using a laser printer with OHP slides ?

Edit.

Actually... I have a 100W laser cutter, and I may try the trick that a few people have blogged about, where you use black spray paint to form the resist and use the laser to burn off the paint where the board needs to be etched.
Unfortunately it takes way more than 100W to remove the copper, and also if I had a laser which was that powerful, its likely to start cutting into the fibreglass as well as the copper.

PS. I didnt spend a fortune on the laser, its a heavily modified, cheap 30W chinese laser, but I replaced the tube with a much bigger profession 100W tube, and did a lot of mechanical modifications to the machine so that it would fit (well, it doesnt fully fit inside, I had to make the machine bigger !)

zmemw16
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Re: Racemaniac's postbag

Postby zmemw16 » Wed Mar 08, 2017 12:52 am

i wonder if it's being used to make a stencil for depositing solder paste :?:


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