Hackaday Links: January 4, 2015

Chips as furniture is now a thing. It started off with a 555 footstool from Evil Mad Scientist and moved on to an EPROM coffee table. Now [msvm] over on the War Thunder forums has constructed a Nixie tube driver table. It’s based on the K155, and as a neat little addition, he’s included a real vintage chip under glass in the table.

Have some tongs, an anvil, and a blowtorch? Make some bottle openers out of framing nails. There’s a lot of variety here in the shapes of the bottle openers.

[Stephen] used a solid state relay he found on eBay to drive some Christmas lights. The SSR failed. That meant it was time to see inside of this relay looked like. The short answer is, ‘a lot of goop and epoxy’, but the traces look big enough to support the current it’s rated for.

Imagine a part of your 3D printer breaks. That’s alright, just print another…. oh, yeah. Well, I guess it’s time to make a bearing bracket out of wood.

The Electronica MK-54 and MK-61 (actually the Электроника МК-54) were incredibly popular Soviet programmable calculators. Now there’s an emulator for them.

[Rue Mohr] found a very cheap TFT display on an Arduino shield. The chip for the display was an SPF5408, a chip that isn’t supported by the most common libraries. He eventually got it to work after emailing the seller, getting some libraries, and renaming and moving a bunch of stuff. If you have one of these displays, [Rue] just saved you a bunch of time.

17 thoughts on “Hackaday Links: January 4, 2015

  1. May be that cheap solid state relay needs a snubber for. The load is essentially inductive – long wires (high inductance), but very little current.

    As for the 3D printer. It would be funny if that wooden part turns out to be more reliable than the printed part.

    1. Re: snubber – from everything I have read, you typically put a MOV across the outputs of an SSR. I once bought a 5 x 5 array of SSRs from a hamfest (mounted on a huge heatsink) – every one of them had a MOV.

    2. As long as there is something there to absorb the energy when you switches off the inductive load. That SSR doesn’t seem to have a snubber inside.

      The only thing to watch out for is that MOV deteriorates over its lifetime as it absorbs energy. A RC snubber designed correctly works well for dv/dt protection.

        1. Hi, I’m the one that opened up that SSR.

          When researching my first SSR, I wanted to buy one off Ebay, but I couldn’t find a single teardown of one. I didn’t know if it would be safe, if it would support the current, etc. So I opened it for other people who were in my shoes.

      1. Bit of a newbie here. I just bought 2 of these SSR’s for a project. I have just been googling what a snubber is. Could you link to a good guide for designing them for AC loads up to 25A? Or maybe a part number for an already built one, I could try to find? Much appreciated :)

        1. Just have to be aware that from the datasheet: Voltage drop = 1.6V @ 25C

          So if you are really switching 25A (don’t switch to the max!), 1.6V * 25A = 40W of heat generated by the SSR
          Since the SSR derates when its plate goes above 80C, you are looking at (80C-25C)/40 = 1.375C/W or less for the heatsink. A CPU heatsink would do nicely though.

          Still having a MOV across the device as additional protection isn’t a bad idea.

  2. Every now and then I wonder if you could start using something like [Youtube warning] for youtube links, like the PDF warning for PDFs. The thing is, there are situations where it doesn’t make sense to click on a youtube link…
    Cheers

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