a bad idea :-P

[mhardy6647]

I want y'all minimalist tube hi-fi folks to promise me that if you ever build one of these, you'll use an isolation transformer! :-)

From RCA receiving tube manual RC-20:
This type [60FX5] has extremely high power-sensitivity and can be driven to full output by a ceramic or crystal phonograph pickup. [or a line level input]

[Celt]

Yepper, there was a lot of that back then in radios, records player, guitar amps, etc.

[Redboy]

Yikes! Count me out.

[cableguy]

What....:headscrat:stupid:






Bill

[fsjonsey]

Yepper, there was a lot of that back then in radios, records player, guitar amps, etc.

You sure wouldn't want to play the guitar in your socks on a concrete floor with one of those.

[Celt]

You sure wouldn't want to play the guitar in your socks on a concrete floor with one of those.

No, but I bet the few who did peed their pants!

[ejfud]

It's all pops and whistles to me, but I'll take your word for it.

[shelly_d]

:yikes: this :thumbsdn: is :nono: bad :no: news :worried:

Ejfud:

This design brings the power from the outlet into the amp and uses it directly in the design. The two filiments are directly accross the line voltage and the high voltage in circuit is taken directly off the same spots. That means that ALL the current that an outlet can supply (15 to 30 amps depending on the fusing, circuit breakers in the home) is available for instant flow into and through you, the user, if there is a fault in the amp. I didn't study the design long enough to see if signal ground and power ground are joined, but if they are, there is a real potential for 120 volts to be sitting on the chasis of that puppy. Can put a bit of a crimp on a good day that kind of thing can. Transformers serve a safety function as well as an electrical one. They isolate and limit the amount of power coming in from the line:yes:.

Hope this explains things for you.

Shelly_D


Edit: The signal ground and chasis ground are hooked directly to the line cord. All it takes to energize the chasis to 120 volts is to plug the thing in backwards or for the outlet to be reverse wired - more common then most would think.

[currituckco]

Don't worry - there' a fuse!

[Blue Shadow]

What is the Murphy's Law about fuses...the most expensive or rarest part associated with a fused unit will fail thereby protecting the fuse. In this case that rare part seems to be the user.

[mhardy6647]

Don't worry - there' a fuse!
Under some conditions, the end user (emphasis on "end") will be the fuse.

[fsjonsey]

It's amazing how many transformerless sets carried the UL sticker, all of my AA5 radios do. Of course, the requirements were probably more lax back then.

[Celt]

Things were wired with non-polorized plugs back then too. Seriously, live chassis were the norm when I was growing up. Many things were wired in series, even including solid-state table radios.

[bricktop]

I guess back then they didn't expect people to be idiots and sticking their hands where they shouldn't be, but that would be a lawsuit waiting to happen today, people sue for anything these days:thumbsdn:

[wa2ise]

In a manufactured product, this amp would be hidden inside the case of the record player, away from casual contact. The "chassis" and pickup ground, which would likely include the record changer metal base, has a 0.22 megohm and 0.1 cap between it and the powerline. Used to limit the shocking currrent to something that won't usually kill you. And the speakers are isolated via the output transformers (no feedback circuits here). So, in normal use, it isn't that dangerous to listeners, but the turntable is probably more "dangerous" to the vinyl being played, with a needle tracking at 10 grams...

[jaymanaa]

I guess back then they didn't expect people to be idiots and sticking their hands where they shouldn't be, but that would be a lawsuit waiting to happen today, people sue for anything these days:thumbsdn:


Yep, and back then they didn't have warnings on fan belt packaging warning the user to "shut off engine before attempting to install new belt". No kidding, it really says that on Gates sleeves.:no:

[soundmotor]

I guess back then they didn't expect people to be idiots and sticking their hands where they shouldn't be,

Once upon a time common sense was passed directly from parents to children.

[E2theNth]

conversing with idiots is to philosophizing with bricks.

[mhardy6647]

Once upon a time common sense was passed directly from parents to children.

That's because natural selection took care of the rest.

[Fran604g]

I still remember the first time (~1963) I touched the radio on the kitchen counter and the sink faucet at the same time, NEVER again. That's when I learned about grounds. (Thanks Dad) :D

[WopOnTour]

Don't worry - there' a fuse!Yea, but unfortunately it's not a 100mA fuse (about the amount of current required to put you into fibrillation) :thmbsp:
WOT