Mechanical Relays

If the coil voltage is OK, give them and a transformer to pre-teen kids to play with.

The young kids will enjoy seeing the contacts move, and might learn to respect electricity if they get zapped by back EMF when breaking the current to the coil.

I taught my daughter to be careful around electricity by getting her to touch an electric fence with the back of her hand. I touched it first, and educated her as to why the back of the hand was safer than inside her grip.

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** Where are they ?

** Switching the AC supply, low cost changeover & multi-pole switching, simple small signal switching without loss.

They do pretty much everything better stupid mosfets except switch at high speeds.

..... Phil

Haha, mechanical relays vs MOSFETs, IGBTs. Some PROs:

• much lower capacitance (sub pF) * handle higher current (contactors) * lower voltage drop (sub uV, zero) * handle higher voltages (30kV, yep) * lower power (latching types)

Here's an example of a 100A 1.2kV switching application that benefited from a relay taking over most of the time. From the new x-Chapters book: Fast magnetic-field shutoff.

--
 Thanks, 
    - Win

Keep them, the thing I most regret is getting rid of my first car, worth more than the house now, or the Truvox reel to reel tape recorder - worth damn all even now but still a thing of wonder and beauty !

Imagine if I'd kept all the OC44 and other OCxx transistors I had when I

Show us some pictures (of your relays) - and if nice, I'll show you a picture of the inside of my ancient Sullivan inductance bridge (and see if anyone can identify the weird variable transformer things).

MK

would be less than the UK inflation rate (1920% according to

S&P 500 gained 16148% nominal in that period (in USD).

- Andi

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** I remember seeing OC44s back in the 60s, cos it was safe for kids to pla y with battery powered stuff.

If you scraped the black paint off one, they made dandy photo-transistors.

..... Phil

At first, some of the later ones had opaque gunge inside - I can remember my Dad explaining this to me. The gunge may not have been malicious - maybe bright light could get through defects in the black paint.

MK

I didn't realize you guys were into relays. And here I have shelves of them - NOS - that I was going to put up for sale when I got around to it. Mercury wetted, regular, timer, etc...

Picked these up from a radio/TV parts retail/wholesaler (Main Electronics in Vancouver, BC) where the owners died (father and son, real nice guys) and the family sold off the inventory. Parts going back to the 60s...

John :-#)#

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shutoff.pdf?dl=1

Noted, Win! And before I forget, let me thank you sincerely for your input iro the spectrum amplifier X-amplifier. Your analysis of the schematic made it *way* easier for me to work out what had gone wrong with it and it's now up and running again with a *full* horizontal trace, thanks entirely to your good self. Exemplary!

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I'd like to, but the really interesting ones are all currently out of reach on a hill of vintage components surrounded by a moat of small fragile components behind a wall of large and heavy test equipment. Sigh. It's such a mess here.

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This little Fujitsu DPDT is fabulous.

That's about 3 GHz equivalent usable switching.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

On Oct 29, 2019, Winfield Hill wrote (in article ):

Win,

Just curious - does AoE cover mercury-pool ignitrons?

.

Think of it as a *very* large and rugged thyratron, suitable for an aluminum pot line, for instance.

I suppose solid-state thyratrons could be used to drive the igniter (gate) terminal. Maybe.

Joe Gwinn

A Ferrari that originally sold for $4,000 in 1963 sold for $38 million in 2014, for a gain of 950000%. [1] (Inflation, dollar devaluation, creating ever more dollars, is a financial mechanism that gives politicians a blank check to squander as they see fit.)

Most of the mechanical relays in my small collection came from broken battery backups. The current revision of Tripp Lite's SMART1500LCD contains four KLT1C20DC24 relays and two 894H2AH1 relays. Tripp Lite certainly knows about the merits of power MOSFETs, as thirteen P60NF06 are also used. Heath/Zenith's HZ-5411-WH motion activated security light system also uses a relay, something along the lines of a RUT-SS-124DM. But it's special order now; it's apparently been dropped from retail shelves to make room for LED security lights, which seem better suited to solid state solutions. The K180V3 Rolling Code kit [2] contains four mechanical relays. DIY Kits being being DIY Kits, you will probably always find one or more DIY Kits stuffed with one or more mechanical relays.

Note.

[1] [2]

Thank you, 73,

--
Don Kuenz, KB7RPU 
There was a young lady named Bright Whose speed was far faster than light; 
She set out one day In a relative way And returned on the previous night.

It still worked as photo-transistor despite of the gunk.

I made a telephone using OC71's for receiving and flashlight bulbs for sending. The antennas were discarded car headlight reflectors.

And, yes, an incadescent bulb could be modulated with speech. In

1960 there were no LEDs yet.

--

-TV

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** The "gunge" was silicone grease.

Harmless, thermally conductive and obviated the need for vacuums.

Lotsa Germanium devices had the stuff packed inside.

..... Phil

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** I have read the neon lamps were use to expose film for audio tracks on e arly talkies. Avoiding the need for synchronised vinyl discs.

Think vacuum photo tubes were use for pickup.

That is, until PVs cam along.

.... Phil

A relay is more likely to survive static discharges, nearby lightning etc.

Sometimes I do use relays as a source of winding wire - it is hard to buy small quantities of very fine gauges any other way. If you do this then I suggest that you store it in the original relay. This way it is more compact (much packaging is required to store winding wire without scratching its insulation), avoids unnecessary damage to the wire due to re-winding onto a spool, avoids investing your time in the work of re-winding it that may never pay off if you happen not to require the wire, and allows you to use the relay as a relay if that turns out to be more useful to you sooner.

No. But we do discuss thyratrons, in connection with high-voltage pulse-forming networks, in Appendix H.3

--
 Thanks, 
    - Win

relay coils are already on spools

NT