Update On the Trace Eliott ELF That I Blew Up.

[-Asdfgh-]

IDK, maybe. AC to DC linear power supplies would have had larger components.

Still smaller than a cabinet or a tube amp, I'd expect.

Last gig I was doing lights and sound for I had issues with hum when the band's new DMX UV lights were connected to one of the house DMX feeds. The house wiring used three pin DMX over one of the balanced connections from stage to the mixing station, driven from the lighting desk. That's getting even more off topic, though.

 

[Old Garage-Bander]

Back in the day, half-wave rectifier power supplies were more common. That meant that the rectified voltage had the same frequency as the line voltage. It was expensive to build and operate power diodes back then because they were tubes. When silicone power diodes came around, full wave "bridge" rectifiers became commonplace. This meant the rectified voltage could be twice the power line frequency. That made filtering a lot easier, using smaller, lighter, less power hungry components.

 

[delta7fred]

C battery for bias.

I completely forgot the grid bias battery!

 

[TomB]

He hasn’t logged in since Tuesday March 20th. Possibly he doesn’t like us no more!

Likely this wasn't the advice he was hoping for...

 

[BassmanPaul]

I completely forgot the grid bias battery!

On some tube amp schematics I’ve seen the bias supply labeled as C - that’s C Minus.

 

[Al Kraft]

On some tube amp schematics I’ve seen the bias supply labeled as C - that’s C Minus.

Finally, something that's still familiar to me from my school days!

 

[BassmanPaul]

I still have the books I was presented with as my school prizes. In one math exam I received a mark of 99%. When we reviewed the papers, I had the correct answer to every question but one was marked as being wrong. I argued that I should have had 100% but the teacher wouldn’t change the mark. I was miffed I was!

 

[Al Kraft]

Probably not an issue with incandescent bulbs.

Or at least more manageable given that the mass of the heated filament and filament material selected could be optimized to prevent much of a dimming that might otherwise be noticeable with current at that frequency. You'd probably also detect the flickering/strobe effect more at 25 Hz if you used an older style resistance type circuit dimmer.

 

[Al Kraft]

I still have the books I was presented with as my school prizes. In one math exam I received a mark of 99%. When we reviewed the papers, I had the correct answer to every question but one was marked as being wrong. I argued that I should have had 100% but the teacher wouldn’t change the mark. I was miffed I was!

I kept everything from school too. I even have my study course notes for the Engineer in Training exam I took (and thankfully passed) when I graduated from college. I had a turbo-machinery prof who pulled a similar stunt on me and to this day I still remember wanting to beat him senseless with his own slide-rule.

 

[Old Garage-Bander]

I kept everything from school too. I even have my study course notes for the Engineer in Training exam I took (and thankfully passed) when I graduated from college. I had a turobo-machinery prof who pulled a similar stunt on me and to this day I still remember wanting to beat him senseless with his own slide-rule.

I once questioned a grade I received from a physics professor because he gave me a final score that was greater than he had previously told us was possible.

100% on the multiple guess part and for the essay, he took an especially particular liking to my explanation of how the universe began.

 

[Killed_by_Death]

too soon?

 

[agedhorse]

In 1989 we moved some textile machinery that ran off of DC. Said machinery was still operation untill about 97.

D.C. was used because of the ease of controlling speed with simple field control. This became popular post lineshaft era.

What kind of textile machinery? One branch of my family was involved with industrial scale embroidery looms way back.

Yeah 400 cps mains means a great reduction of size and weight for filter caps and inductors in the power supplies. I suppose PS transformers as well? And in the tube days, there were a lot of inductors used in power supply filters.

Mainly for the reduction in the size of transformers, motors and actuators on aircraft

How? If you rectify and smooth it it is 25Hz. Full wave rectification makes that 50Hz. Both are more difficult than the 50/60Hz that we use today.

Rectifiers weren't available, or used much in the very early days of electricity. Mostly lighting and motors (which almost double in size at 25Hz).

Still smaller than a cabinet or a tube amp, I'd expect.

Last gig I was doing lights and sound for I had issues with hum when the band's new DMX UV lights were connected to one of the house DMX feeds. The house wiring used three pin DMX over one of the balanced connections from stage to the mixing station, driven from the lighting desk. That's getting even more off topic, though.

The most common cause off such ground loops is the lighting ground on the DMX not being fully isolated from pin 1, which then leaks to the audio ground via the shields in a typical snake. DMX is generally well isolated via opto-couplers used between devices on the network.

Or at least more manageable given that the mass of the heated filament and filament material selected could be optimized to prevent much of a dimming that might otherwise be noticeable with current at that frequency. You'd probably also detect the flickering/strobe effect more at 25 Hz if you used an older style resistance type circuit dimmer.

The problem with making the filament heavier is the loss of efficiency on an incandescent bulb. Fluorescent bulbs have a bigger problem for a different reason.

I once questioned a grade I received from a physics professor because he gave me a final score that was greater than he had previously told us was possible.

100% on the multiple guess part and for the essay, he took an especially particular liking to my explanation of how the universe began.

I had a question on a final asking for the definition of the universe... and to give 3 examples!

 

[BassmanPaul]

I had a question on a final asking for the definition of the universe... and to give 3 examples!

Ah but! Did you pass? Enquiring minds need to know. LOL

 

[Al Kraft]

Fluorescent bulbs have a bigger problem for a different reason.

I would think the older magnetic ballast systems would be most affected, whereas the newer electronic ballast systems could probably easily be designed to overcome the issue. Although even with magnetic ballast and 25 Hz AC I would assume the flicker would be at 50 HZ (the voltage to goes to 0 twice per cycle), and for short duration I would think most folks would find that okay.

IIRC 50 CPS is the place where most folks start to become comfortable that they have a continuous light source. Although I have read studies where working fro long periods of time in fluorescent light with magnetic ballast (and the associated 120 CPS flicker rate) still caused physical symptoms like fatigue, eye strain, and headaches.

 

[Al Kraft]

Ah but! Did you pass? Enquiring minds need to know. LOL

My guess is that's what convinced him that he was better off in engineering than the humanities! At least most of the engineering, math, and science tests (except theoretical physics and power plant balance equations) had real answers, plus or minus 10%.

 

[Kevin1960]

I'll bet there are as many theories as there are people to provide an answer. My guess is that there was likely a set of trade-offs that may have included accepting higher insulation requirements and protocols for allowing the use of smaller copper in the wiring that led Europe to make its choice for higher voltage. As for the US, I think Edison having sort of set things up for us to be a 110-110 Volt (albeit DC) country by his initial design choices and the magic number sort of stuck for convenience.

As for 50 or 60 Hz, my guess is that there are too many variables to even begin to make a compelling case, but that at least for the US Tesla's initial calculations zeroed in on 60 Hz as a good optimal compromise between competing options. Even in the US we have varying standards in different industries. For instance aircraft often use 400 Hz AC to allow for downsizing of components (equal performance with less volume and mass). However, that only works well because the wiring/electrical system is very "local" - transmitting high frequency AC over long distances is not efficient/economical.

The battle between AC and DC for the grid standard was I think between Westinghouse/Tesla (AC) and Edison (DC). The electrification of Niagra Falls was the start of the power grid system in U.S., and it was at that time a decision had to be made before the generators were to be installed. Westinghouse won the bid, in spite of Edison's inventive display of the electric chair to prove the dangers of AC technology. I also think the ability to send power over longer distances by AC played into the process as well.

 

[Son of Wobble]

 

[Kevin1960]

I forgot to mention that 60hz. was something that was chosen for the ability to be dividable by 3. A 50hz. systems did not lend itself well to 3 phase which was something that heavy industries at that time in the U.S. desired to use.

 

[BadExample]

View attachment 2962755

Bad Batman! Bad Batman!

 

[BadExample]

For instance aircraft often use 400 Hz AC to allow for downsizing of components (equal performance with less volume and mass).

It also tastes funny if you cut into a hot phase with insulated dykes. Young AT's can handle it though.