Surprised No one has mentioned Topsy The Elephant during the AC verse DC wars of long ago. I never did care for Thomas Edison.

Topsy was not a healthy animal. I’m fact he was dying and the zoo was looking for a way to put him out of his misery. Ironically, Edison was unaware of the incident. The zoo contracted with the Edison Company ( nothing to do with Thomas Edison.) It wasn’t even his company. The rest is urban legend.

 

Topsy was not a healthy animal. I’m fact he was dying and the zoo was looking for a way to put him out of his misery. Ironically, Edison was unaware of the incident. The zoo contracted with the Edison Company ( nothing to do with Thomas Edison.) It wasn’t even his company. The rest is urban legend.

Interesting... I didn't know that. But Topsy was not the only animal electrocuted to demonstrate the dangers of AC, according to Edison (or the Edison company) ... am I right?

 

Evidently none consider the advice offered in my previous post. Certainly electricity can be dangerous, and that means that all those working with it need to understand exactly what they are dealing with, and exercise adequate precautions. That is a lot different from being paralyzed by fear.
So the means to avoid the danger is knowing what one is dealing with and understanding what to do and what to not do.

 

Couldn‘t agree with you you more, I rarely see those tube amps like I used to so, these days, I get complacent. Recently I saw a hazard in a machine that switched AC neutral to shut off the DC switching supply, then it left the AC HOT which was 18 ga wires to an AC heater without clear labeling or even sane wire colors (they chose red and black) for 120 VAC.

 

Interesting... I didn't know that. But Topsy was not the only animal electrocuted to demonstrate the dangers of AC, according to Edison (or the Edison company) ... am I right?

Yes they used other animals, but the elephant got all of the press.

 

Worst shock I ever got was from a B & W TV that was off. Apparently, I found a capacitor charged to some high voltage. Knocked me on my ass. Have been much more cautious since. When I salvaged an MOT, I didn’t open it until it had been off for a month.

Bob

 

The glass capacitor formed between the inside and outside coatings on a glass CRT is one of the best capacitors around as far as leakage goes. If that second anode area is clean it can hold a charge for over a month. The good news is that the shock does not carry a lot of power, and it is over fairly fast. So they are fairly safe.

 

The glass capacitor formed between the inside and outside coatings on a glass CRT is one of the best capacitors around as far as leakage goes.

AKA Aquadag.

 

Aquadag: Made by the Acheson Chemical Company. "Dag" means "Dispersed Aques Grahite" used as a moderately resitive coating on cathode ray tubes. On the inside is usually an aluminum coating.

My boss and I were having a discussion at a lab bench. One of the things on the bench was a 14" color CRT. As we talked my boss pensively tapped the anode button on the tube. I said "Be careful of the high voltage charge." My boss continued to tap the button saying "What charge...IEEEEEEEEEEEYA!

The good old days of small CRTs and only 25 kv on the anode.

 

I think Ac v DC has had an interesting past

https://www.energy.gov/articles/war...ernating current,the solution to this problem.

 

This thread has wandered off into a thicket. Time for it to end.

 

I think Ac v DC has had an interesting past

https://www.energy.gov/articles/war-currents-ac-vs-dc-power#:~:text=Edison developed direct current --,the standard in the U.S.&text=Tesla believed that alternating current,the solution to this problem.

I have heard this also, that we are talking about some incredibly high voltage to reduce the current and allow smaller wires to transmit power.

 

I have heard this also, that we are talking about some incredibly high voltage to reduce the current and allow smaller wires to transmit power.

Really, the higher voltages are to allow more power without increasing the resistance losses. Look at that new string ofpower lines along I-94 in north-central Wisconson. Those insulators must be 3 feet long!

 

Couldn‘t agree with you you more, I rarely see those tube amps like I used to so, these days, I get complacent. Recently I saw a hazard in a machine that switched AC neutral to shut off the DC switching supply, then it left the AC HOT which was 18 ga wires to an AC heater without clear labeling or even sane wire colors (they chose red and black) for 120 VAC.

There have been plenty of times I thought power was off only to discover that sage advice - "Turn the breaker off first". Switched neutrals are common among older homes in America.

Worst shock I ever got was from a B & W TV that was off. Apparently, I found a capacitor charged to some high voltage. Knocked me on my ass. Have been much more cautious since. When I salvaged an MOT, I didn’t open it until it had been off for a month.

Worst I ever got from a CRT was (estimating) 65KV. Right in the chin. Felt like Mike Tyson punched me in the jaw. Hurt for three days. No burn though.

 

Worst I ever got from a CRT was (estimating) 65KV.

The highest CRT anode voltage I have ever encountered on my HV probe was 25Kv

 

Many new high voltage, long distance lines use DC since the power transmitted is equal to the peak voltage times the current, not 0.707 of the peak voltage times the current, and it has no reactive AC losses.

 

Many new high voltage, long distance lines use DC since the power transmitted is equal to the peak voltage times the current, not 0.707 of the peak voltage times the current, and it has no reactive AC losses.

The province here uses DC transmission for all the Hydro lines, also very large saving in 2 conductors instead of 3.
Another plus is very little effect to the end user from lightening strikes.

 

Another plus is very little effect to the end user from lightening strikes.

mind elaborating?

 

mind elaborating?

The effects get trapped during the local SCR conversion stages. (Prior method, via Ignitron's).

 

@MaxHeadRoom , really? Did they use ignitrons to handle that kind of power (hundreds of kw)?

High resolution color CRT displays from the mid-80's until they were edged out of the market by flat panels in the early 2000's had anode voltages of about 27 to 27.5 kv. The chassis designer did not choose the voltage -the tube and yoke designers chose that.

I worked at a small re-startup where we took new high resolution CRTs and put them through a process during which the tube was not in a chassis and I crept the anode voltage up to 45 kV to burn off any sharp bits of metal that might cause arcing later on. That was a hair-raising experience!