Digest for sci.electronics.repair@googlegroups.com - 8 updates in 5 topics

makolber@yahoo.com: Oct 10 08:08AM -0700


> Absolutely, but I recommend speaker fuses. One good trick to keep the fuses form introducing distortion at high level low frequencies (this is not audiopholery, it is measurable) is to make a high value bipolar out of like 2 8,200 uFs in series +to+ and put it across the fuse. That only DC or very low frequencies will blow it. For this amp all you would need is 35 volt units.
 
I agree the distortion is measurable but it may still be audiopholery.
 
How much are we talking about due to the fuse?
 
And how much distortion will the speaker itself create at that frequency/ level?
 
m
jurb6006@gmail.com: Oct 10 08:45AM -0700

>"How much are we talking about due to the fuse?"
 
That has to do with the type of fuse and the current drawn by the speaker since it is dependent upon the low thermal mass of the fuse element. The resistance increases with temperature. All it takes is a part of that element to get warm. A large enough capacitor across it will keep that from happening. In fact if you want to risk it to save a few bucks you can get a super high capacitance with low ESR and a lower voltage rating. Of course if the fuse blows then the cap will explode.
 
>"And how much distortion will the speaker itself create at that frequency/ level? "
 
People who care and buy expensive speakers usually get quite low distortion from them. My Boston Acoustics A-150s IIRC were rated 0.7 % which is phenomenally low for a speaker. Really, most of the cheap junk is more like 3 - 5 % at any decent listening level and it is mostly odd order harmonics. However with a decent crossover that is just harmonic distortion, the fuse will also create intermodulation distortion because all frequencies go through it. I would say that is much more audible.
 
Lower power ratings don't really help because you would use a commensurately lower value fuse and its thermal mass will be less. A slow blow is probably better but then it comes down to how much abuse to which you are willing to subject your woofers. Some of them are quite expensive.
bruce2bowser@gmail.com: Oct 10 02:42AM -0700


> If you install it yourself, fuck all that noise about a pipe threader, get the precut, threaded gas (sometimes
> called "black") pipe and then the unit goes where it goes and you adjust the water lines to accomodate. Almost
> anything is easier to deal with than thickwall 1" steel pipe.
 
Installing that might need a gas service shut-off AND an electric utility shut-out before work begins in addition to everything else. Just to make sure the random spark doesn't find its way in.
 
> If the existing tank here goes I will know alot more because we do not call contractors,
 
Then you bear future insurance costs instead of them.
"pfjw@aol.com" <peterwieck33@gmail.com>: Oct 10 06:09AM -0700

I used flex and a flaring tool. Flare-nut fittings are reliable, simple (remember to put the nut on before making the flare!), and effective. So, black-iron to include the drip-leg, and flex to make the last 18". I have a cut-off at the tank, at the T-fitting, and at the heater itself. Power is on a wall-switch nearby.
 
Neat, simple and safe.
 
Inspected by the Propane Supplier and passed.
 
NOTE: Many gas cut-off valves require considerable hand strength, or have very short handles. I installed devices such that were kid and wife-tested. They do exist, usually for a couple of bucks more. They are well worth it.
 
Peter Wieck
Melrose Park, PA
jurb6006@gmail.com: Oct 09 03:04PM -0700

I asked about having it picked up and it doesn't look good. So I guess I have to choice but to pass.
rmalsbury50@gmail.com: Oct 09 01:52PM -0700

I can send you a complete manual if you want via email if you still need one.
 
My little scope still works, of course, it needed some attention!
 
Robert M
Cursitor Doom <curd@notformail.com>: Oct 09 05:45PM

On Mon, 08 Oct 2018 15:01:48 +0000, 698839253X6D445TD wrote:
 
 
> That is nothing, even before I was borm I would stick my hand out of
> mama's and grap the iron to practice soldering.
 
Good Lord! I had no idea you were such a precocious child, Jan! ;-)
 
 
 
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Cursitor Doom <curd@notformail.com>: Oct 09 05:47PM

On Tue, 09 Oct 2018 17:45:02 +0000, Cursitor Doom wrote:
 
Precocious *embryo* I should have said. :)
 
 
 
 
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