two switcher circuits

Cute. Sure is going to need some input filtering though!

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

I have to resist the temptation to put bypass caps across voltage sources in Spice. The LTM8078 apparently has inductors but no caps. Even that is impressive. Can anybody x-ray one for me?

--

John Larkin         Highland Technology, Inc 

Science teaches us to doubt. 

  Claude Bernard

Not a switcher, but expedient:

Driving the adj pin of a 3t regulator is an under-appreciated trick. They are nice, cheap, thermally limited power amps.

We have standardized on 24 volt warts for small boxes, so we want to switch mostly. So multiple outputs from tiny switchers is good.

Just minutes ago I got this:

The idea is to get away from the boring Hammond boxes. This is a semi-custom extrusion with nice grounding and thermals. We plan to laser blast the anodize for external artwork.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

dl=0

Who made those boxes for you? I have an upcoming project where I need something similar.

--
Chisolm 
Texas-American

They cut one of their extrusions to length and machined it per our drawing. The blue anodize color is a little garish, so we'll ask them to tone it down a bit next time.

The holes are drilled/tapped after anodize, so are conductive and don't have the problems that the self-tappers do on the Hammond boxes. Like metal shavings everywhere and stripped screws.

We add a couple of metal bars inside that the board bolts to.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

I noticed that the LM317 is OK with its input sitting about 4-5" from the +/-50 switcher output filter caps, but without some extra filtering closer to the regulator the LM337 is unhappy about it and starts oscillating at low frequency

Hammond makes some nice transformers at reasonable prices for e.g. vacuum tube amps but their enclosures sure are drab!

My eyes! My eyes!

Yeah, it would be good to get them to tone it down a bit. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

What part number is this? What color specification?

--

  Rick C. 

  - Get 1,000 miles of free Supercharging 
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The 337's pass transistor is an NPN, so its output is via the collector, much like modern LDOs. It's a perfectly good part when used as directed, but far less forgiving than the emitter-follower 317.

And tsk tsk on using those parts from a 50V supply--or are you using the HV variants? (IDK if there's any difference apart from testing, of course.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

Get serious, I'm only running 2 mA in that LED. We were wondering how it would look, just the led on the PCB and a hole drilled into the end plate. The light bounces around in the hole and it actually looks pretty good from all angles. Don't need no light pipe.

I kinda like it, but some other people here don't. The Chinese seem to like bright primary colors, and it generally looks good on them.

We're investigating getting a 20-watt n/c fiber laser to blast the lettering in-house.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

It's the case I'm referring to. I might have a low threshold, but electric blue anodize screams "aliexpress" to me. Of course, we're still using the black Hammond boxes round here, so perhaps it's my inner Amishman talking. ;)

Fun.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

Oh, I knew that.

We found the Hammonds to be mechanically messy too. They don't always saw the ends off the extrusions at a 90 degree angle.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

Very nice.

Never ever use self-tappers. They work loose with vibration, and cut new paths when you re-insert them. You don't even need to tap if you use trilobular (thread-forming) screws. Taptite is one brand, but it's a DIN standard.

CH

The input-output voltage differential on the top and bottom 317 and 337 exceeds the 40V limit for about 200 microseconds on startup with the

+/-50 rails coming up in the sim way faster than they actually would IRL. I think it'll be okay. It's not going into production it's a place-holder to test the main board until I can get around to buying or building a PS that doesn't consume so much power for the client

Shipments are suffering delays to my location and my girlfriend is in our home in another state (RI) that's banned non-essential cross-border traffic, I'm not a RI resident, and they're busting and fining people they seem to be serious about it. let the Constitutional scholars fight over it later.

some of my gear is stuck there, while I'm working on caring for an elderly parent up here at home in MA, no way she's staying some other place right now.

Doing some under-the-gun engineering here lol

People extrude 3/4 holes in things like this, and then use self-tapping screws. The partial holes tend to break taps.

--

John Larkin         Highland Technology, Inc 

Science teaches us to doubt. 

  Claude Bernard

People don't make things to be serviced. Self-tappers can be ok in the absence of vibration or the need to service.

Tapping deep holes in Al is fraught - the correct technique involves lots of reversals, and in large sizes, multiple passes with different taps, so it's slow.

CH

That could be bad. I haven't seen that problem from them, but maybe I've managed to avoid Monday morning boxes. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com