How best to connect toroid transformer to pcb/circuit

LateraLiz

Member
2019-08-21 3:13 am
Greetings!

I've reached the home stretch with regards to finishing up the PCB design for my first linear power supply build, but I now realize I am unsure how "best" to connect my transformer to the pcb/circuit. The transformer in question:
AS-0518 - 50VA 18V Transformer - AnTek Products Corp

Obviously I can just solder the tranfo wires to the PCB, but I was wondering if something like using terminal blocks or maybe JST connectors, etc, is advisable (or not)?

Forgive me if this has been discussed here before. But I tried using the search function and couldn't come up with anything. Thanks in advance.
 

nenad88

Member
2016-11-06 11:28 am
Maybe spade connectors?

spade_connector.jpg
 
Screw terminals and bootlace ferrules even? Mashes the wire less, allows colour-coding to your scheme. Pluggable terminal block connectors are nice too. All these methods are rated for decent current levels. Arguably screw terminal blocks are less mechanical strain on a pcb than spade terminals, and a bit more compact / space efficient.

Spades and blades are commonly used in loudspeakers/crossovers because they can be fitted easily without needing to get a screwdriver in - and drivers already use them anyway, and compactness isn't really relevant.

One point in favour of screw terminals is during testing and protyping they are pretty flexible for wiring up a test setup without having to make up special leads, you just need wire. With plugs and sockets you need to make up test fixtures using them - breakout boards in effect.


For production its a different story, proper connectors speed up assembly, and all the cabling will typically be pre-made, even the transformers would be ordered with specific cable termination. I doubt that's relevant here!
 
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LateraLiz

Member
2019-08-21 3:13 am
Screw terminals and bootlace ferrules even? Mashes the wire less, allows colour-coding to your scheme. Pluggable terminal block connectors are nice too. All these methods are rated for decent current levels. Arguably screw terminal blocks are less mechanical strain on a pcb than spade terminals, and a bit more compact / space efficient.

Spades and blades are commonly used in loudspeakers/crossovers because they can be fitted easily without needing to get a screwdriver in - and drivers already use them anyway, and compactness isn't really relevant.

One point in favour of screw terminals is during testing and protyping they are pretty flexible for wiring up a test setup without having to make up special leads, you just need wire. With plugs and sockets you need to make up test fixtures using them - breakout boards in effect.


For production its a different story, proper connectors speed up assembly, and all the cabling will typically be pre-made, even the transformers would be ordered with specific cable termination. I doubt that's relevant here!

I was leaning toward using bootlace ferrules and screw terminals from the start - you really can't beat how neat and tidy this makes installation, while minimizing the things you mentioned, such as wire strain etc. However, being new to all this I didn't know if there were any reasons why this wouldn't be advisable. Seems like sometimes even the most minor of choices, such as using a blue led instead of a red or a green one to indicate power status, can introduce more unwanted noise into the circuit(!). :rolleyes:

Thank you for providing such a detailed summary outlining a few of the main choices here, Mark! I'll make sure to post the finished effort here soon, and allow everyone here to rip it to shreds, err i mean critique it. :cool:
 

LateraLiz

Member
2019-08-21 3:13 am
So I may have overlooked a potentially crucial detail with regards to wiring this thing....there's a single purple wire connected to the primary, which the product description mentions being connected to earth ground during dielectric testing. Is this mystery wire, in fact, supposed to be connected to ground?

product:
AS-0518 - 50VA 18V Transformer - AnTek Products Corp

If thats the case, I'm guessing its designed to serve in shielding the primary from secondary or something, right?
 

LateraLiz

Member
2019-08-21 3:13 am
Do not create a shorted turn
Easier than you think to do
Do not connect any wires to the center mounting bolt either
Connect the purple to the chassis or Earth connector where your wires enter

I was just gonna mount the xmfr onto the chassis, as in drill hole, place bolt with rubber pads, etc. Or is that a bad idea since i'll have the purple wire connected to chassis via earth? Would this be avoided by connecting purple to earth at the ac inlet where the wires come in instead, or am I supposed to be mounting the xmfr on a little platform to avoid contact with the chassis? I might be over thinking this..