Power supply wisdom

Phil Hobbs · 2012-07-09T20:31:19+00:00

I'm designing a photodetector for moderate-quantity production (probably 1000-5000 units over its lifetime).It needs a few power supply voltages inside, like+3.6 for the micro, < 50 mA+- 15V for the analogue stuff+50-75V for the photodiode bias.It only dissipates a few watts total, mostly from +-15.Total BOM cost including box and board, excluding supplies, is about $220 at most. DC-DC converter modules are expensive enough that they'll add another $100 to this, which stinks.Sooo, it looks like I can build my own DC-DC with several outputs, and post-regulate them. Not awful, but will need a custom transformer.However, it occurs to me that I could very easily use a 12-14 VAC wall wart, and do it the old-school way with a couple of half-wave regulators and a Cockcroft-Walton tripler for pretty cheap--mostly the cost of the caps, which should be under $10 altogether in 100s.One drawback is needing different wall warts for different markets, but that isn't a terrible problem in this instance.Alternatively, I could use a +18V wall wart, one inverting switcher, and a charge pump / Cockroft Walton.Suggestions? Pitfalls? Input protection advice?CheersPhil Hobbs-- Dr Philip C D HobbsPrincipal ConsultantElectroOptical Innovations LLCOptics, Electro-optics, Photonics, Analog Electronics160 North State Road #203Briarcliff Manor NY 10510845-480-2058hobbs at electrooptical dot net

Jul 09, 2012 66 Replies

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miso 14 years ago

On my monitor, that image is about 4x real life! Yeah, it it was that big, no problem.

The microusb nearly fits in both ways. The old mini had an angular look to it. There was no way to mistake how it went in. The microusb looks a bit rounded.

Firewire is the other standard where might makes wrong.

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Fred Abse 14 years ago

I had a guy force a UHF plug into an N jack. Looked quite innocent, took a while to discover where the infinite VSWR was coming from.

Both connectors 5/8"UNF, see?

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

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Fred Abse 14 years ago

Phones keep getting smaller. Unfortunately fingers don't.

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

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Jan Panteltje 14 years ago

On a sunny day (Thu, 12 Jul 2012 09:00:52 -0700) it happened Fred Abse wrote in :

Maybe wait a few generations.

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krw 14 years ago

4" screens don't make for tiny buttons. ;-)

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Joerg 14 years ago

Oh, ya mean those phones with them thar flat screens whar ya hafta be peckin' in da number instead of pushing dem buttons?

Regards, Joerg http://www.analogconsultants.com/

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krw 14 years ago

Dats der won.

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