EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: MathWizard on October 01, 2021, 11:41:48 pm
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I was looking at some old Heathkit test gear schematics, and most of it has ganged/multi-wafer switches. And just checking ebay, the prices get pretty high very fast, like they are made of Gold and by Santa Claus/Elves.
Anyone know of a good place to order them , or order the parts, and u put them together your self ??.
Or what about modern IC switches, with low Rds(on), I bet chip IC switch resistance can't be worse than dirty old switches on lots of vintage test gear that still works fine.
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Depends on what you want, number of poles, frequency, current. I suppose the local thrift stores are filled with printer selector boxes that have big rotary switches in them.
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A year or so ago I wanted a complicated switch. I had nothing close in my junkbox so I asked on the web. I ended up with two switches from different people. I think it was something like 8 pole 4 position, more or less.
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Another alternative is to use relays, with the control functions sorted out by ("old school") a diode matrix, or a microcontroller.
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Check out Tayda! They have many, up to 12-position decks, and way cheaper than Santa's elves!!! I've bought several and been happy with them.
Also a great place to load up on jellybean parts in general--cheapest LEDs I've ever seen, and they work. I've generally been quite happy with my Tayda purchases.
Relays can work too. I need a 33 uF variable capacitor for a project, which I'm going to build by ganging capacitors in binary cascade fashion (16.5 uF, 8.25 uF, 4.13 uF, etc), each with a relay going between it and one of the gang rails. The controller? A 12 bit ADC running off a panel pot!! Ha!
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How many poles and how many positions do you need?
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I don't have a project in mind, it's just there's lot's of old analog test-tech that all use them, whose design's I could copy.
I did buy some nice single wafer 12-postion switches from Tayda, for a resistance box I made.
I'd never want to use a whack of common mechanical relays, too loud and expensive. Reed relay's can be nice, but add a lot of stuff.
I guess if I had a big sheet of some insulator, little metal rods, spring wire, sheet metal, plastic, .....I could try making them. But I have a hard enough time getting motivated to make a wooden box for projects, I need a real work shop with a vice, etc.
What about a pile of JFET's? I guess for anything like that, the AC considerations would have to be fully accounted for.
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DIY wafer switches: they have made these for ages:
https://www.farnell.com/datasheets/12335.pdf (https://www.farnell.com/datasheets/12335.pdf)
I got to this data sheet from the Newark web site. They were around before the web was invented. And they still are.
Probably other brands, just search for "wafer switch" and exclude places like Amazon and E-Bay.
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Yes, do exclude places like Amazon and eBay.
I just had a shop around to see if anyone was selling a used Picoscope 2204A, as mine has gone south. Not only did I not find any used ones on eBay, there are several new ones for sale, for prices !!up to US$384!! I bought mine in 2015 for US$149, and they're still US$149 right this minute from Pico Tech!!!
Am I missing something, or is this 'One Born Every Minute' :-// marketing?
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Jameco has quite a few as well.
https://www.jameco.com/c/Electromechanical.html#/filter:ss_category:Electromechanical (https://www.jameco.com/c/Electromechanical.html#/filter:ss_category:Electromechanical)$253ESwitches$253ERotary
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https://www.ebe.de/de/produkte/schalter-taster-encoder/schalter-taster.html (https://www.ebe.de/de/produkte/schalter-taster-encoder/schalter-taster.html)
Anything you want - including hollow shaft for second switch, pushbutton function, etc.
https://www.elma.com/de/products/rotary-switches (https://www.elma.com/de/products/rotary-switches)
as above
https://www.electro-nc.com/ (https://www.electro-nc.com/)
https://www.blore-ed.com/rotaryswitches (https://www.blore-ed.com/rotaryswitches)
https://www.grayhill.com/productattributesrotary (https://www.grayhill.com/productattributesrotary)
https://www.nkkswitches.com/products/rotary/#gref (https://www.nkkswitches.com/products/rotary/#gref)
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One must always be wary of prices, but I have nothing against Amazon or eBay and I use them often. It is just for this particular item, I thought it was better to look to more traditional sources.
And I sometimes get the impression that far too many of the younger group in the profession and hobby never even know that real electronic supply houses even exist.
Yes, do exclude places like Amazon and eBay.
I just had a shop around to see if anyone was selling a used Picoscope 2204A, as mine has gone south. Not only did I not find any used ones on eBay, there are several new ones for sale, for prices !!up to US$384!! I bought mine in 2015 for US$149, and they're still US$149 right this minute from Pico Tech!!!
Am I missing something, or is this 'One Born Every Minute' :-// marketing?
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I have sold items on eBay myself, and have a fossil up for auction right now. It's not their fault if people are offering items at ridiculous prices. But it's more likely to happen there than with businesses that cater strictly to the electronics crowd, where competitive shopping is likely to occur. I've been buying from DigiKey since their catalog was a one page flyer, so I have a good gut feel for what is probably a ridiculous price on most electronics items. You're right... people who grew up with a little blue screen lighting up their face may think bigger is better, so why go to Joe's Tronix Stuff when you can go to eBay? Answer: because he sells hundreds or thousands of items, so cruising such sites quickly gets you a feel for prices.
eBay may be good for clothing and jewelry, but for specialty items, it ain't always the one stop shopping some might imagine. How do you compare oscilloscopes for sale by anybody and everybody when prices range from scary cheap to insane ripoff? What's a sensible price to pay? See who's been selling lots of scopes for decades and you'll get a good idea quickly.
Speaking of which, Amazon is proving not to be a good place for clothing and jewelry. They have been found to be doing business with knockoff artists and skewing search results to steer you to them. Maybe that's why Jeff Bezos is so incredibly rich. Scary thought... Amazon is branching off into grocery shopping...