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etpm@whidbey.com: Dec 06 10:04AM -0800 I would post this in the basics group but it seems like there are more responders here. Anyway, I have been looking at DIY single ended tube amp schematics recently. These are modern schematics using grounded power cords. And several have in common that the power switch is in the neutral line and the fuse in the hot. Wouldn't it be safer to have both the switch and fuse in the hot line? Thanks, Eric

John Robertson <spam@flippers.com>: Dec 06 11:36AM -0800 > both the switch and fuse in the hot line? > Thanks, > Eric   For a 3 wire power system (with grounded chassis) that is incorrect as you suspect.   For a two wire power then it is correct to have the switch on one side of the line and the fuse on the other as you don't know (unless the plug is polarized) which side is hot when plugged in.   John :-#)#   -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."

etpm@whidbey.com: Dec 06 11:49AM -0800 On Thu, 6 Dec 2018 11:36:53 -0800, John Robertson <spam@flippers.com> wrote:   >of the line and the fuse on the other as you don't know (unless the plug >is polarized) which side is hot when plugged in.   >John :-#)#   Ahh, that makes sense. I bet a lot of the designs copied existing older circuits where possible. Thanks, Eric

"pfjw@aol.com" <peterwieck33@gmail.com>: Dec 06 01:07PM -0800 On Thursday, December 6, 2018 at 2:37:02 PM UTC-5, John Robertson wrote:     > For a two wire power then it is correct to have the switch on one side > of the line and the fuse on the other as you don't know (unless the plug > is polarized) which side is hot when plugged in.   There is that. I tend to replace line cords with those using polarized plugs, if possible, and then keep the fuse (if any) and switch on the 'hot' line.   General, I would not add a fuse to an AA5, but rather use a purpose-made fused box, plugging the radio into that. In such a way, the fuse level could be varied, and the hot will surely be fused in any case. '   The problem with converting old amps to 3-wires is a matter of hum-loops. Just don't do it. Polarizing the plug is fine. There is a very long explanation of why this is so, but "hum loop" should be enough.   But, at no time with a repaired/restored amp should power exist on the transformer or chassis with the power switch in the "OFF" position. Full Stop.   Peter Wieck Melrose Park, PA

tabbypurr@gmail.com: Dec 06 01:43PM -0800 > both the switch and fuse in the hot line? > Thanks, > Eric   You're right, that is obsolete practice from the days of unpolarised ungrounded power cords. I don't think it ever had any advantage from a safety perspective, it was just fractionally easier to terminate the mains cord onto a switch & a fuse.     NT

Ralph Mowery <rmowery28146@earthlink.net>: Dec 06 05:03PM -0500 In article <J7Odnbth_avL55TBnZ2dnUU7-ePNnZ2d@giganews.com>, spam@flippers.com says...   > For a two wire power then it is correct to have the switch on one side > of the line and the fuse on the other as you don't know (unless the plug > is polarized) which side is hot when plugged in.   I am getting into this late.   When replacing the line cord on an older 2 wire cord ( no ground) with a 3 wire grounded cord, which is the perferred method ? Go from the hot wire to the switch or the fuse first, then to the other and transfromer , back to neutral ? Of course the grounded pin on the plug goes to the chassis and the 120 VAC is isolated from the chassis by the transformer.   Several of us were discussing this the other day, but none of us knew for sure which should come first, switch or fuse in the 3 wire 120 vac equipment.   It did seem that in the older ARRL Handbook the 2 wire cords had the fuse on one side and the switch on the other side of the transformer.

tabbypurr@gmail.com: Dec 06 02:36PM -0800 On Thursday, 6 December 2018 22:03:43 UTC, Ralph Mowery wrote: > equipment.   > It did seem that in the older ARRL Handbook the 2 wire cords had the > fuse on one side and the switch on the other side of the transformer.   Fuse & switch should both be on the live side. Fuse should come first, switches do sometimes short. Wires to switches can also come adrift.     NT

Sjouke Burry <burrynulnulfour@ppllaanneett.nnll>: Dec 07 01:43AM +0100 On 6-12-2018 23:03, Ralph Mowery wrote: > equipment.   > It did seem that in the older ARRL Handbook the 2 wire cords had the > fuse on one side and the switch on the other side of the transformer.   A 2-pole switch would be the first thing I would add.

Look165 <look165@numericable.fr>: Dec 07 12:54PM +0100 Maybe your wall plus is not respecting the norm.   So, what you call neutral might the the phase line.   To comply to safety rules, manufacturers must protect the phase line, not the neutral (VDE, UV, IEC, ANSI...).

Look165 <look165@numericable.fr>: Dec 07 01:54PM +0100 Maybe your wall plug is not respecting the norm.   So, what you call neutral should be the phase line.   Seen from you, the phase should be on the right, neutral on the left (plug in the wall).   It's easy to check, take a voltmeter (scale 500V AC), take one end (barefoot), and put the other one in the plug (each holes, one by one). You have no risk ; if it is the phase line , the meter should move a little. Don't forget that if you put the meter in Amperes, you will reach the cieling.   To comply to safety rules, manufacturers must protect the phase line, not the neutral (VDE, UL, IEC, ANSI, ISO...). So your wall plug connexions might be inverted.     Look165 a écrit :

Fox's Mercantile <jdangus@att.net>: Dec 07 07:14AM -0600 > both the switch and fuse in the hot line? > Thanks, > Eric   Almost all of those projects aren't done by engineers. They're done by people parroting one another.   Back in the "good old days" of two wire non-polarized line cords, the standard procedure was one side went to the fuse, if it had one, the other side went to the switch. There was no engineering behind that decision, it was strictly manufacturing, "We need one less tie point."   Look at it as a series loop. It doesn't matter the sequence that anything is connected in.   Three wire line cords: Hot, to fuse holder (The point at the far end of the fuse) then to the power switch. Not that you should rely on an open fuse to keep your fingers off the hot side of a line inside a chassis.   -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com

Look165 <look165@numericable.fr>: Dec 07 02:47PM +0100 I said with a voltmeter 500 VAC (some 1MOhms) in between you and the phase, The measure should show about 5-10 VAC if you don't come from the shower but barefoot.   The neutral is easy to check ; around 5-10VAC betweent neutral and ground (a water pipe for instance or a heater in case of collective heating).   Fox's Mercantile a écrit :

jurb6006@gmail.com: Dec 07 03:50AM -0800 On Tuesday, December 4, 2018 at 1:59:29 PM UTC-5, Fox's Mercantile wrote: > Jeff-1.0 > WA6FWi > http:foxsmercantile.com   You have all the fun.

rndus5572@gmail.com: Dec 06 11:51PM -0800 > Solution Manual and Test bank Absolute Java (6th Ed., Walter Savitch) > Solution Manual The Art and Science of Java (Eric Roberts) > Solution Manual Buildi... i want Solution Manual Electronic Principles (8th Ed., Albert Malvino, David Bates) .my email id is rndus5572@gmail.com

Phil Allison <pallison49@gmail.com>: Dec 06 08:01PM -0800 Ralph Mowery wrote:   > > ** DMMs don't come with shielded leads, only scopes do.   > You missed the part where it is a VTVM, not a DMM.   ** I was particularly interested in the fact the Eico is a VTVM.   > The old VTVMs I have seen often have a shielded probe.   ** Mainly because they are such wide band meters, covering the range up to several MHz. Most only have one input connector, a coaxial type, switched between DC and AC use.   However, the Eico has a separate DC voltage jack and that is the one the OP asked about.   Modern DMMs have similar input impedances to VTVMs ( like 10 or 11 Mohms) and full scale DC ranges starting from 2V rms.   So very comparable.       ..... Phil

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