Ace Posted November 21, 2003 Report Share Posted November 21, 2003 Okay folks, here's the dealio: While looking for schematics, I've come across the fact that wiring a ground connection to the bridge can be a possibly lethal danger many times. I've also noticed that some people were trying to alleviate those problems by adding capacitors to their schematic, which do offer a protection, but at the same time render the whole concept of bridge grounding for noise reduction useless. Thinking about the problem, an idea entered my mind that seemed so obvious to me that it led me to the following train of thought: a: This problem has been around for a long time B: The solution seems obvious to me c: I'm not the sharpest tool in the shed conclusion: There must be something wrong with my idea, or else somebody would have come up with it many years ago. Enough beating around the bush, my idea is simply to install a small fuse between the jack and the bridge ground which will blow in case of a power surge from the amp. estimating the body resistance from hand to foot at about 1.2 kOhms and keeping it safe estimating the minimum power surge at 100 vols, the current would equal 83.3 milliamps, which shall be rounded down to 80 milliamps for the fuse. My questions are now: 1) would it change the sound to have a fuse in the signal chain? 2) are 80 mA fuses that act quick enough readily available? 3) how high is the nominal signal current in the guitar? (read: would I blow the fuse during playing?) hoping for some profound answers here, so long ace Quote Link to comment Share on other sites More sharing options...
tsl602000 Posted November 21, 2003 Report Share Posted November 21, 2003 I really don't think that'd work..... I use a wireless all the time... just as safe! Quote Link to comment Share on other sites More sharing options...
Ace Posted November 21, 2003 Author Report Share Posted November 21, 2003 Well, what exactly do you base your theory on, that it wouldn't work. That's exactly what I want to know. And of course, wireless is THE safest thing, but some of us can't afford that, it does alter the sound a bit and it looks funny when you play a club stage that's the size of a standard body blank for each member of the band with a wireless system ;-) so long ace Quote Link to comment Share on other sites More sharing options...
Speedy McFeely Posted November 21, 2003 Report Share Posted November 21, 2003 the cap is probably the best soultion. if you could find a fuse that is small enough, it would most likely be expensive. if you properly shiled your guitar, and in a cap, then you will be safe from a tube amp. however, it is a moot point if you have a solid state amp, use a wireless, or active pick ups. if you use an old (some prefer "vintage") tube amp, then a little protection is diserable, but if you can afford a "vintage" tube amp, then you should be able to afford a $125 uhf system. the idea sounds good on paper, but electricly speaking an electric guitar shouldn't make any sound at all, but FM it works. Quote Link to comment Share on other sites More sharing options...
MikeB Posted November 21, 2003 Report Share Posted November 21, 2003 i dont think itll work, as there are a few governing factors here. 1. fuse blow speed 2. 10mA is enough to stop your heart 3. resistance b/w foot and ground would be in the mega ohm region fuses typically are designed to blow within minutes, some more, even quickblow fuses will take a while to blow, while the damage is done. and 80mA fuses are uunheard of i think, unless specially made or somthing, and these wouldnt break in time. the fuse works by heating a filament up, like a bulb, and when its hot enough the steel/tungsten i think filament breaks, 80mA aint gonna melt it! i dont like the being earthed to the guitar thing, so i bought a pair of active EMG's which dont earth external parts, so its safer! hope this helps mike Quote Link to comment Share on other sites More sharing options...
Speedy McFeely Posted November 21, 2003 Report Share Posted November 21, 2003 there are also ground boxes that you plug your guitar cord into, before the amp, then this box gets plugged into the wall socket, not for power but for building ground, work good, also quiet the signal a little. Quote Link to comment Share on other sites More sharing options...
Ace Posted November 21, 2003 Author Report Share Posted November 21, 2003 Umm, okay mike, but http://www.physics.udel.edu/wwwusers/watso...s/clas0308.html says something else about the amount of current that is lethal, which I've found backed up by a few other pages, too. I also don't understand the "resistance between foot and ground" passage correctly I think. I'm not trying to cling to a dangerous idea only because it's mine, I'm just trying to find out if it is feasible. And yes, I have seen 80 mA fuses at my local electronics suppliers website and if I'd had the time I'd have gone there this afternoon and asked somebody over there, but unfortunately I didn't. The ground boxes that Speedy brought up is an interesting thing however, I had not heard of those before, but I'd like to hear other opinions on that, we all know how anally retentive us guitarists tend to be when it comes to tone... so long ace Quote Link to comment Share on other sites More sharing options...
bluespresence Posted November 21, 2003 Report Share Posted November 21, 2003 I don't think it's all that crazy of an idea however I would disagree with the table listed on the link. 5mA = some muscle paralysis in children (the can't let go syndrome) 10-15mA = same as above for most adults 20-30mA = Houston we have a problem 40mA-60mA = Uhhh, see ya.... I'm an electrician by trade (20+years) and these are the numbers we live by (or die by if you're not careful). Fast blow fuses are available in very small amperages as you found out, but I think you may have a problem with the filament being too fragile and breaking at the most inopportune time, like the middle of the solo you practiced for 3 months and finally played perfect. Like speedy mentioned you can pick up a wireless system on the cheap if you shop around. Find a local music store that does rentals and see if they'll sell you a rental unit for cheap. PS: I play wireless Quote Link to comment Share on other sites More sharing options...
Ace Posted November 22, 2003 Author Report Share Posted November 22, 2003 I own a wireless system. However I wanted to check out a simple and rather cost-effective possibility. I think I'm going to buy a fuse socket and some quick-blow fuses in assorted amperages, just solder the socket into my strat and experiment with the fuses to see if they're sensitive to the stress of being played in a couple of rehearsals. Gonna have to wait till next week tho because I can't get to the shop tomorrow and have a gig on sunday anyway so I won't have much time for tinkering. Thanks for the advice though, all of you so long ace Quote Link to comment Share on other sites More sharing options...
MikeB Posted November 22, 2003 Report Share Posted November 22, 2003 if you do fit a fuse ffs dont test if it blows quick enough by pluggin your guitar to the mains and earthing yourself!!!!!!!!!!!! mike Quote Link to comment Share on other sites More sharing options...
Ace Posted November 22, 2003 Author Report Share Posted November 22, 2003 lol I didn't plan to...I wanted to test it with our drummer so long ace Quote Link to comment Share on other sites More sharing options...
MikeB Posted November 22, 2003 Report Share Posted November 22, 2003 lmao he probably wouldnt notice anything anyway, if hes like my drummer!!! mike Quote Link to comment Share on other sites More sharing options...
jener8tionx Posted November 23, 2003 Report Share Posted November 23, 2003 Here's my 2 cents... 1. The fuse idea is a good one. With a light fuse, 80ma you protect yourself against sudden surges of electricity, if a large bust comes through the line, it's not going to take minutes to blow, it will be damn near instant, there is a limit to the nuber of electrons that can pass through the wire at a time, if it is lower voltage, and the fuse isn't going to blow instantly, you will FEEL it and be able to react. My Fender has ha this wire on it since the day I bought it, and no problems yet. I didn't even concve of thie problem until now. If you are really scared of being shocked to death, maybe the best solution is to remove the wire and just shield the crap out of the pickup and wiring. If it was me...and it is with my fender, I'd just instal very light gauge wire like the type in pickup wiring that cannot conduct much electricity. Also the fuse won't blow with normal use, I mean think about it, the current is going through the guitar as you play it right? Are you getting shocked all the time? no, so it can't be enough current to blow the fuse with normal use. PS, anyone who sees flaws in my logic/reasoning, please point them out to keep the integrity of this post. Quote Link to comment Share on other sites More sharing options...
westhemann Posted November 23, 2003 Report Share Posted November 23, 2003 umm...well i built my very first guitar 13years ago out of spare parts from friends and i forgot to ground the bridge...on a high humidity day it would shock the piss out of me.i have never been shocked by a properly grounded guitar. Quote Link to comment Share on other sites More sharing options...
lightbulbjim Posted November 25, 2003 Report Share Posted November 25, 2003 I heard of a guy doing what jener8tionx said, and just using very light wire for the bridge grounding. It's a similar sort of concept to the fuse really, I don't know what would be the advantages/disadvantages between the two. Quote Link to comment Share on other sites More sharing options...
rob Posted November 25, 2003 Report Share Posted November 25, 2003 ummm, stoopid question, but how come actice circiuts dont have the bridges grounded? Quote Link to comment Share on other sites More sharing options...
Southpa Posted November 25, 2003 Report Share Posted November 25, 2003 Pretty much all wiring schematics don't show exact ground wiring. They will just show the little ground "arrow" symbol, the rest is up to you. Grounding the bridge, which in turn grounds your strings and tailpiece is to be taken for granted, its just not mentioned. I've never owned a guitar yet that didn't have some sort of bridge grounding. As far as setting up any fusible links, etc. inside the guitar I don't really think its necessary. If you end up with ANY kind of amperage strong enough to fry wires inside your guitar then you better ground your amp properly and stop playing in the rain. The guitar I just built has a stainless steel pickguard. I stripped about 1 1/2" off the end of a wire, pushed the end into the hole for the TOM bridge post and then laid the pickguard down on top of the remaining bare wire. I then hooked the wire to one of my central grounding points, in this case a volume pot. All of my pots are linked together with a ground wire and then a wire from the last pot goes out to my plugin. Along the way I have ground wires feeding in from pickups and pickup selector switch. Sort of like a river with tributaries feeding in, no ground loops. Quote Link to comment Share on other sites More sharing options...
BigG1986 Posted January 12, 2007 Report Share Posted January 12, 2007 (edited) [quote name='westhemann' post='37631' date='Nov 23 2003, 01:39 PM']umm...well i built my very first guitar 13years ago out of spare parts from friends and i forgot to ground the bridge...on a high humidity day it would shock the piss out of me.i have never been shocked by a properly grounded guitar.[/quote] This might be why my mates guitar onlyshock me on certain days manly when we'r jamming in a cold damp garage we as a mechanical engineer who lighty brushed on electrical components and i mean lightly, i think the fuse is a good idea, but the best option seems to be that earth box thing that works inline. But would two diodes in the right direction on the jack point no work as that would mean if a surge did come up throught the ground the dioe wouldn't let it enter the guitar and wouldnt blow meaning that u would have jst lost one guitar for the rest of the set!! just an idea but would it work??? Edited January 12, 2007 by BigG1986 Quote Link to comment Share on other sites More sharing options...
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