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Here is a nice single point description of the various sizes, current ratings, construction methods and applications for TE Connectivity/AMP brand "Faston" connectors that go with spade terminals.
http://www.te.com/commerce/Document...ERMINALS_-_FULL_CATALOG&DocType=CS&DocLang=EN
The PCB mounted "spade" terminal (aka blade, tabs, Faston, etc) I think this is one of the best inventions to come to PCB building and assembly.
I have built about 30 amplifiers, most from the Solid State Forum, and 99% of the amps there use PCB spade connectors to allow quick and reliable assembly and disassembly of the PSU connections, the speaker connections, and GND from the amp. They are reliable, secure, low cost. They also reduce strain that a solder pad is subjected to, so the connection is more resistant to mechanical stress and re-installation. If you have one (or a couple) standard PSU's and heatsink cases, but like to try a lot of amps - this is a godsend. I can swap an amp in 1 minute, and have no fear of pulling a flying lead solder pad off because the spade spreads the mechanical stress over two large soldered pads (with solder fillets).
I have built several amps designed and layout by folks in the Pass Forum. NO ONE here uses spade connectors. The amps I have built here, are great with the exception that they are pain to install and remove, and having just installed and removed them twice, all are experiencing solder pad liftoff/peeling where thick PSU flying leads are connected.
I know, "Mr Pass doesn't use them on his amps, so why should we?" Because he builds commercial amps that are meant to be assembled just one time. For DIY use, I implore designers here to start using them, or at least add a secondary hole spaced 5mm apart to give constructors the option of installing a spade if they desire. I would like to build more Pass Class A amps, but it drives me nuts to uninstall flying leads from the amp/PSU or amp/speaker.
I have heard arguments that "connectors" are evil and unreliable. In my experience, the opposite is true. I have not had a spade connector fail on me or be the cause of a poor connection.
While we are at it, why are audio input connections also flying lead? Please use JST terminal blocks, or Molex connectors, etc...
You will not find a major commercial PCB that has flying leads in any high reliability application. This includes cars, spacecraft, satellites, jet fighters, appliances. They need 100% reliability and they all use connectors to the PCB.
For example:
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Why not install a short flying lead with a 1/4" spade on the end of it if you want easily removable amp boards?
You still have strain induced pad liftoff from the floppy wire to PCB solder joint. Plus, you are adding a piece of wire and free space floppy joint when it is so simple to add a second hole for the tab to be soldered onto a secure board.
if you want to build them that way , be my guest
also - I'm my own guest
, if I don't want to build in that way
so - everyone is happy
also - I'm my own guest
, if I don't want to build in that wayso - everyone is happy
I have had the opposite experience. I've pulled pads right off removing female spade connectors from boards.
It' probably because I'm a ham fisted guerilla.
I'm preferring the PCB mount screw terminals lately - like:
282836-5 TE Connectivity | Mouser
I lightly solder the very tip of stranded wire to give it more thickness deep in the cavity so it will never pull out involuntarily. Maybe re-torque a couple hours later.
It' probably because I'm a ham fisted guerilla.
I'm preferring the PCB mount screw terminals lately - like:
282836-5 TE Connectivity | Mouser
I lightly solder the very tip of stranded wire to give it more thickness deep in the cavity so it will never pull out involuntarily. Maybe re-torque a couple hours later.
if you want to build them that way , be my guest
also - I'm my own guest
so - everyone is happy
Certainly, if I did the layout myself I would do it, but if building for example, your layout or Tea Bag's layout, etc. it would be nice if the board has pads for spades as an option. Hence, why I am requesting (or imploring) designers to accommodate.
These take a lot of board real estate and I have found to be not as reliable as spade connectors. They can loosen.
I take screwdriver and squash that little locking bump in the middle of the female connector. They can handle 'normous amperage - as used for large AC appliance motors like air conditioners.
I've had plenty of them fail. Admittedly in one of my other hobbies (old cars) where the operating conditions are considerably more dire.
But they still give me the willies.
Cheers,
Jeff.
PS: Here's a different kind of amplifier: this amplifies the signal from a probe in the radiator header tank to turn on a light on the dashboard when the coolant is low. Circa 1979. The diode had failed short-circuit, but I also replaced the three transistors while I was there.
An externally hosted image should be here but it was not working when we last tested it.
I dislike any kind of convenience connectors in my final assemblies. Meaning the ones I use for actually listening to music.
Call me audiofool or whatever, but I can hear the difference with and without them.
This includes interconnects, source switches, and the like. I would even remove the volume control if I lived in an isolated residence 🙂
Having a testbed assembly is a different discussion. There I usually prefer double screw connectors on cables
I believe spade connectors are only mandatory on mains connections.
As for lifting pads, designing them reinforced is always a good idea
Here is a closeup of the part footprints that I am using
Call me audiofool or whatever, but I can hear the difference with and without them.
This includes interconnects, source switches, and the like. I would even remove the volume control if I lived in an isolated residence 🙂
Having a testbed assembly is a different discussion. There I usually prefer double screw connectors on cables
I believe spade connectors are only mandatory on mains connections.
As for lifting pads, designing them reinforced is always a good idea
Here is a closeup of the part footprints that I am using
Attachments
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Actually a spade connector only has a gas-tight joint along the edges of the rolled-in sides of the female connector. All the other bits of it will oxidise and become high-resistance.
The flat in the middle makes a pretty tight (maybe not gas tight) connection too - this is where the locking bump/tab is. But when I look at the flats on my spade after pulling them out, the flat is shiny from mechanical wear during insertion/removal process.
Yep, as I said, large contact area 😉 and under sprung tension too, better than any screw terminal
I think you'll find that the flat in the middle does not stay shiny after insertion and before removal.
That being said, I do agree with Scott that a sprung connection is better than any screw terminal.
Speaking of which, I use wave washers under my transistor mounting bolts. However, I suspect that at these small dimensions they don't really have any effect. Anyone else?
That being said, I do agree with Scott that a sprung connection is better than any screw terminal.
Speaking of which, I use wave washers under my transistor mounting bolts. However, I suspect that at these small dimensions they don't really have any effect. Anyone else?
I service one type of equipment that uses faston type terminals for several things. I've replaced lots of them for loosening up or becoming oxidized and overheating. They have their uses, but not reliable long term.
I have used spades in my latest VFET-X build also, but always in mind to solder them together, after the amp is totally finished.
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