Welcome, Guest. Please login or register.

March 28, 2020, 05:20:49 AM

Login with username, password and session length

Recent Posts

Author Topic: Transformer Tricks  (Read 2986 times)

phatt

  • Legendary
  • ******
  • Posts: 2089
  • Chip Points: 249
    • View Profile
Transformer Tricks
« on: April 17, 2015, 07:51:41 AM »
Could not decide where to put this one?
But how's this for thinkin outside the box?

http://sparkbangbuzz.com/mag-audio-amp/mag-audio-amp.htm

I don't fully grasp this idea but I do know that transformers are clever and hold many secrets. 8|

A bit more here,, which does make some sense;
http://sparkbangbuzz.com/mag-amp/mag-amp.htm
works like a relay to drive a lamp.

But the audio amp part has got me a bit baffled,,,  xP So I'm Open to any explanations about the Trans Amp idea.

Roly

  • Legendary
  • ******
  • Posts: 2184
  • Chip Points: 288
    • View Profile
    • Australian Valve Amps
Re: Transformer Tricks
« Reply #1 on: April 17, 2015, 10:31:59 AM »
Magnetic amplifiers pre-date valves.  I've seen reference to them being used in gun fire control on WW1 battleships.

They are simple, robust, and capable of quite high power.  They are also inherently heavy and waveform distorting - an ideal servo amp on a big ship, not such a great audio amp.

Saturable reactors still get used occasionally for high power AC control, but it's getting rarer.

The audio amp is a bit like Class-D.  The 35kHz is the carrier that switches the core from state to state, the audio applied on another winding biases this switching up or down resulting in 35kHz PWM output.

If you think these are fun then you should visit a surviving cousin, the ferro-resonant Constant Voltage transformer, still widely found.
If you say theory and practice don't agree you haven't applied enough theory.

teemuk

  • SSGuitar Global Mod
  • Legendary
  • ****
  • Posts: 1074
  • Chip Points: 282
    • View Profile
« Last Edit: April 18, 2015, 05:42:13 PM by teemuk »

Roly

  • Legendary
  • ******
  • Posts: 2184
  • Chip Points: 288
    • View Profile
    • Australian Valve Amps
Re: Transformer Tricks
« Reply #3 on: April 18, 2015, 08:53:13 PM »
Thanks for those teemuk, but I hope you will forgive me for being a tad under-whelmed.

The US Navy publication from 1951 has a long list of MagAmp applications, and in 1951, just when solid-state devices were being invented, the MagAmp looked like an attractive proposition compared with valves (tubes).

Within a couple of decades that hopeful list would be shredded by an even better device, and the MagAmp, like the valve, effectively became a historical oddity.  {too odd, it seems, for even the excited Golden Eared Hyper-Fi-ist community.}

The Germans also did a lot of development between the wars of cold-cathode "gas" valves which were capable of astonishing amplification factors, but like MagAmps these were also swept away by devices and techniques that didn't suffer from their inherent limitations.

MagAmps still do what they always did, but it's hard to think of any application these days were the sensible designer wouldn't walk right past obscure MagAmp technology to something a bit more commonplace that works better.  Newer Melbourne trams for example use SMPS for smooth traction and regenerative braking, something MagAmp's can't match.  Worse, the advent of SMPS has made the winding of iron core transformers of any sort, let alone complex ones, an endangered art.

The Navy document gives a good impression of where things stood in 1951, but also shows how rapidly and how much things have changed since.  The MagAmp flip-flop is particularly amusing when you consider that your computer now contains several million solid-state flip flops.

I love steam engines too, but yagotta be practical.

{And I still sometimes take out a USB Ramstick or mini-SD card and just look at it in wonder.  Gigabytes of non-volatile storage, when my first computer had 512 bytes of usable space and drew amps of current.  :o }
If you say theory and practice don't agree you haven't applied enough theory.

phatt

  • Legendary
  • ******
  • Posts: 2089
  • Chip Points: 249
    • View Profile
Re: Transformer Tricks
« Reply #4 on: April 22, 2015, 09:16:29 AM »
Thanks for the explanation Roly.
If I ever build a battle ship I'll call you for help on gun controllers.  :lmao:

And thanks for the links Teemu.
Yes I did read the Auditorium23 link but way beyond my ability to build.
Also at 19 KG's for a 2 x 15 watt amp is a little over weight for me. :-\

Re the US Navy pdf;

I like the preamble where it mentions all the possibilities such as;
Magnify, oscillate, modulate, switch,,pulse, etc.
And offer low maintenance ,,close to indestructible and can handle 170,000 Amps.. :o
Holy sparks batman! That would make the Batmobile go like a V12 Merlin on steroids.

But tiss good to read these things even if only to learn how we got to now. :dbtu:
Phil.

Roly

  • Legendary
  • ******
  • Posts: 2184
  • Chip Points: 288
    • View Profile
    • Australian Valve Amps
Re: Transformer Tricks
« Reply #5 on: April 22, 2015, 01:04:57 PM »
Well, leaving aside the 39kHz power oscillator, when you want lots of horsepower these things get big.  And heavy.  Great blocks of steel and lashings of copper.  Not really ideal for aircraft.   8|


(big 3-phase transmission tranny under repair)


(moving decommissioned power station transformer)

I think the ferrite ring amp looks like fun - a MagAmp Cricket.
If you say theory and practice don't agree you haven't applied enough theory.