stonehenge regulator

On 27/09/2019 00:38, Gerhard Hoffmann wrote:

<snip>
> 
> No more banshees and demons.
> Nowadays: tourists, by the 1000s.
> 
> 
> The parking lot is 5 Km away, and an endless stream
> of people between the parking lot and the stones.
> 
> We gave up. The picture is a drive-by shot from the
> country road, from the moving motorbike. Wide angle lens,
> obviously without looking through the camera and later
> cropped/rotated in the computer.
> 
> And we got wet!
> Riding a submarine would have been appropriate for that trip.

> Gerhard

The origins of this one are much better documented...
https://en.wikipedia.org/wiki/Achill-henge

Cheers
-- 
Clive

Am 27.09.19 um 10:21 schrieb Clive Arthur:

> 
> The origins of this one are much better documented...
> https://en.wikipedia.org/wiki/Achill-henge

Constructed over a weekend?
They should be hired to finish the new Berlin airport!

I have also seen this one on Iceland, still under construction:

< 
https://www.flickr.com/photos/137684711@N07/36430535453/in/album-72157688304045365/ 
    >

/Gerhard

At the lab we have several of these:

<https://despair.com/products/revelation>

Cheers

Phil Hobbs

On Thursday, September 26, 2019 at 5:56:15 PM UTC-4, John Larkin wrote:
> I have a 48 volt power supply and I want to drive a lot of relays...

And what's wrong with old tech?  :)

I just approved two designs with the LM2575HVT, another "simple switcher" part.
If you want reduce the chances of over-voltage, you can stick a 56-ohm resistor on the input, without too many hurdles to overcome.  That does waste some power, though.

Do they make the 2567 in a fixed 12-volt version, so you can remove those programming resistors?  I see in the photo that you're using the adjustable version.  Also, do you the really need the 12-volt zener?  Is that for kickback on the line or what?

On Fri, 27 Sep 2019 04:33:40 -0700 (PDT), mpm <mpmillard@aol.com>
wrote:

>On Thursday, September 26, 2019 at 5:56:15 PM UTC-4, John Larkin wrote:
>> I have a 48 volt power supply and I want to drive a lot of relays...
>
>And what's wrong with old tech?  :)

Looks like nothing! Efficiency is mediocre, but I'll have a 600 watt
power supply, and nothing is getting very hot. The inductor is
stressed and is the warmest part. At that frequency, it should be more
like 500 uH instead of 100, but a 500 uH 1+ amp inductor would be a
monster. I have that 100 uH in stock.

The 1-volt ON drop of the switch isn't a big deal when the supply is
48.

>
>I just approved two designs with the LM2575HVT, another "simple switcher" part.
>If you want reduce the chances of over-voltage, you can stick a 56-ohm resistor on the input, without too many hurdles to overcome.  That does waste some power, though.
>
>Do they make the 2567 in a fixed 12-volt version, so you can remove those programming resistors?  I see in the photo that you're using the adjustable version.  Also, do you the really need the 12-volt zener?  Is that for kickback on the line or what?

Two resistors are a small price to pay against stocking a zillion
different fixed-voltage parts.

I probably don't need the TVS at the output. I was thinking about a
startup overshoot, but that actually wouldn't matter in my
application... it wouldn't harm anything. The 48V supply will probably
come up slow anyhow. I have one coming in from Amazon, to test.

This is astounding:

https://www.amazon.com/gp/product/B00G8UDEQ8/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Free Prime 2-day shipping. 13 cents per watt.



-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

On Thursday, September 26, 2019 at 5:56:15 PM UTC-4, John Larkin wrote:
> I have a 48 volt power supply and I want to drive a lot of relays and
> uPs and FPGAs and stuff, so I figured I'd knock it down to 12 volts
> first.
> 
> We have LM2567HV-ADJ in stock, a 52 KHz Simple Switcher probably
> designed by druids during the last ice age. Figured I'd breadboard the
> reg just for fun. A boy gets tired of typing all day.
> 
> https://www.dropbox.com/sh/ajtqs7c1nswfhey/AABi7r0gchljjrxka4aHZItfa?dl=0
> 
> 
> Works pretty well, actually. Nothing gets very warm at 1 amp out.
> 
> Yes, that unshielded drum core will spray field everywhere, but then I
> am simulating alternators.

Isn't that 12V TVS cutting things close?

On Friday, September 27, 2019 at 10:07:29 AM UTC-4, jla...@highlandsniptechnology.com wrote:

> This is astounding:
 
> https://www.amazon.com/gp/product/B00G8UDEQ8/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
 
> Free Prime 2-day shipping. 13 cents per watt.

You can trim Amazon urls at the "/ref="

This goes to the same link:

https://www.amazon.com/gp/product/B00G8UDEQ8

On Fri, 27 Sep 2019 13:47:45 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

>On Thursday, September 26, 2019 at 5:56:15 PM UTC-4, John Larkin wrote:
>> I have a 48 volt power supply and I want to drive a lot of relays and
>> uPs and FPGAs and stuff, so I figured I'd knock it down to 12 volts
>> first.
>> 
>> We have LM2567HV-ADJ in stock, a 52 KHz Simple Switcher probably
>> designed by druids during the last ice age. Figured I'd breadboard the
>> reg just for fun. A boy gets tired of typing all day.
>> 
>> https://www.dropbox.com/sh/ajtqs7c1nswfhey/AABi7r0gchljjrxka4aHZItfa?dl=0
>> 
>> 
>> Works pretty well, actually. Nothing gets very warm at 1 amp out.
>> 
>> Yes, that unshielded drum core will spray field everywhere, but then I
>> am simulating alternators.
>
>Isn't that 12V TVS cutting things close?

A 12 volt TVS doesn't conduct at 12 volts. More like 14.

If the reg fails, it would push 48 volts into 7 PC boards that are all
expecting 12. I could include the TVS and maybe an 0805 series
resistor as sacrifial parts, to localize the flames.

On Friday, September 27, 2019 at 10:07:29 AM UTC-4, jla...@highlandsniptechnology.com wrote:
> On Fri, 27 Sep 2019 04:33:40 -0700 (PDT), mpm > wrote:
 The 48V supply will probably
> come up slow anyhow. I have one coming in from Amazon, to test.

The last MeanWell 48 Volt supply we used in a project took 3 seconds to produce an output.  It did not over-shoot.

John Larkin wrote...
>
> On 27 Sep 2019, bloggs.fredbloggs.fred@gmail.com wrote:
>> On September 26, 2019, John Larkin wrote:
>>>
>>> I have a 48 volt power supply and I want to drive a
>>> lot of relays and uPs and FPGAs and stuff, so I
>>> figured I'd knock it down to 12 volts first.
>>
>> Isn't that 12V TVS cutting things close?
>
> A 12 volt TVS doesn't conduct at 12 volts. More like 14.
>
> If the reg fails, it would push 48 volts into 7 PC boards
> that are all expecting 12.  I could include the TVS and
> maybe an 0805 series resistor as sacrifial parts, to
> localize the flames.

 To protect those parts, use an SCR shutdown with a fuse.


-- 
 Thanks,
    - Win