Transformerless Power Suppply

[NavMicroSystems]

I'm not using any transformerless PSU's at all.

Some time ago I could get hold of a large number of well designed switching PSU-units at about $0,50 each (stock/production overhead)

They provide well regulated 7,5V @ 600mA
and are very small in size.
(Actually not more in PCB-Space than a good transformerless design would require since they are fully SMD)

I could not even design and build any transformerless PSU at comparable cost.

Why develop/build something that is already available on the market at lowest cost?

OK,
for someone selling 10thousands of units per year it is a different story,
but if you are selling "only" several hundreds of units I still feel it is a good option to search the web for those stock overheads.

The only rule is:
get a sample before your bulk order and test it carefully.
If the sample is OK (meets or exceeds the requirements):
order a quantity that lasts at least to the planned production/life-cycle of your product.

That way I have saved a lot of time & money.