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PCB Mount Transformer Pin Spacing ???

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EPAIII:
I have purchased a PCB mount power transformer, Hammond 229A230. It has dual coil primary and secondary so each can be either 115V or 230V. I will be using it to step up from 115V to 230V and the project will only need around 12mA. It is rated at 6VA so it can supply 25mA: their numbers, not mine. So far, so good.



Since this will be a one-off device, I plan to assemble the power supply on perf board. Sounds easily doable. But when I measured the spacing of the 8 pins I came up with a 1.6" dimension between the primary and secondary rows. And the pins in each row are spaced at 3/8" (0.375") apart.

It is a part that is intended to be mounted on a PCB. There is no other provision for mounting it. But in one direction it fits on a 1/10" grid and on the other on a 1/8" grid. This is not the first time I have seen this kind of pin spacing. Transformer manufacturers have been doing this type of thing for many years. And there is sufficient space within the outline of the transformer to easily either widen that 3/8" to 0.4" or to reduce it to 0.3".

I will be able to do a work-around as I have done in the past. File the holes in a standard perf board with a 0.1" grid sideways to allow the pins to pass through the board. And then they can be bent over the foil before soldering. I am not asking how to use it: I have done this a number of times in the past.

But what I want to know is WHY? Why do the transformer manufacturers do this? I could understand if it was a 1/8" or 1/16" grid in both directions. I could understand if it was a 1mm grid in both dimensions. Oh, and I did check. It is not metric in either direction. And I could understand, actually I would expect that it would be a 0.1" grid. The 1.6" dimension tells me that the designer did know that a 0.1" grid was a more or less standard spacing for components in this size range. So why after making one spacing compatible with a 0.1" grid did they then change to a 1/8" grid for the other direction? I can see no sensible reason. Anybody have an explanation?

mariush:
You would still have to remove the copper around the holes near the holes where the transformer pins go in, because you don't want to have 230v jump across terminals (what if you get some water on the pcb for example)

Instead of soldering pins into the prototyping board, you could flip it so the pins are towards the top and enlarge a few holes in the pcb to insert some zip ties through the pcb holes and then have the zip ties around the transformer. If you want to be overkill, add some rubber or sponge between the pcb and plastic of transformer to reduce noise from vibrations in transformer.
Then solder your own wires to the pins, and put some heatshrink over the pins.

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