Mechanical Relays

I do buy some wires from them, but for e.g. 25um wire, their minimum

As an example, the wire in a 12V, 24V or 48V relay can be surprisingly fine, and one tiny relay provides a more than sufficient quantity for my patience, usually for no cost due to my excessive hoard of e-waste. I have the spool from one of these relays stuck on a makeshift spindle running in crude pivots, mounted inside a tin can with a lid to keep dust out, so that when I want some, e.g. for fixing fine PCB traces, I just open the tin and unwind a bit.

Some interesting background on the relationship - or rather not - between the OC71 and OCP71 here (just before halfway down the page):

Are they still in use? Mercury has a bad reputation lately.

GE's early plastic transistors, similar to TO-92 package, were made of a tan expoxy and were photosensitive. That made for some interesting offset and hum problems. A circuit would work great until the boss wandered over to check, and he blocked the light.

Here in the US, it's cheap and easy to get magnet and bus and other wire from ebay or amazon. More official sources, like MWS and electronic distributors, tend to be very expensive.

Watch out for jewelry-type plated "copper" bus wire. It's very stiff and doesn't solder well. Could be hard-drawn, or some cheap alloy.

On Oct 30, 2019, snipped-for-privacy@highlandsniptechnology.com wrote (in article):

They are still made and used, but those units are large-scale industrial, large but few. This is at a level where semiconductors cannot go.

I think that ignitions are special order these days. I would also guess that there are Russian suppliers.

In the earlier wiki, follow the link "Comprehensive Study of High Power Ignitrons

By the way, she references AoE.

In the high microwave region, Gyrotrons rule.

Joe Gwinn

Well, I can't argue with any of that! Thanks.

The compound combination is used in transfer switches, in order to avoid/control arcing across the mechanical contacts.

The semiconductor handle the actual transfer, in some cases while the heavy armatures are still 'in the air'.

RL

Rob, are these hybrid AC-line transfer switches available as standard commercial modules?

Magnet wire is cheap and the enamel can develop cracks during rewinding. I never re-use the wire for that reason. Throw it away.

There are two advantages of mechanical relays: extreme overload handling capability and the low resistance normally-close path. Hard to emulate with a MOSFET -- the best depletion mode ones I know are 300mOhm. It is not unusual to get 10mOhm end-to-end with a relay.

Best regards, Piotr

There are two isotopes of mercury in use, actually. The poisonous one was used in mercury thermometers, which have been recently banned in the EU for that reason. The other, good for the environment, is still used in fluorescent light bulbs as a viable replacement of incadescent devices.

Just exercising doublethink...

Best regards, Piotr

Best regards, Piotr

And a fraction of a pF off. And GHz bandwidth. And DPDT for cheap.

Far more than two isotopes - all of them poisonous! (But you know that already - as do the dentists who still use amalgam fillings.)

John

es.

Not sure what word Piotr intended, but I'm pretty sure it wasn't "isotope". Generally there are three forms of mercury, gas, metal and compounds. Co mpounds can be organic or inorganic. Some are seriously deadly, others are just not very good to have around.

Interesting note, metallic mercury forms amalgams with a number of other el ements including aluminum. A small amount of mercury will essentially diss olve a large amount of aluminum so that it is not allowed on aircraft lest a small spill cause structural damage in a not so visible part of the air f rame.

I was just kidding to indicate that whether mercury is poisonous or healthy depends on the amount of cubic dollars being at the disposal of a particular lobby...

This is how Polish slaves were destroying German aluminum aircraft engines in their factories during WW2. A sure immediate death penalty, but some of them were still doing that.

Gallium is good, too.

Best regards, Piotr

Another example is of course lead. Its not allowed in solder, but car batteries are permitted to use huge quantities. Similarly, large amounts of lead can be used in roofing a building, but lead in paint is forbidden. John

Do you seriously not understand the differences?

Thanks, bookmarked.