There is no physical electrical connection from the house power circuit to the electronics powered by the transformer, thus the transformer provides isolation from the power source. The power transformer magnetically couples energy to its secondary side WITHOUT electrical connection. Contact with ONE part of this circuit, and simultaneously touching an intentional, or unintentional ground can be deadly. Usually a switch and fuse will also be in the circuit. This power transformer is connected to the HOT and NEUTRAL wires of the house power system.
The third GROUND wire started appearing in homes as a safety feature in the 1960's, but a three wire cord for electronic equipment was not mandated until 1969.
Technically the power lines, and therefore the electrical outlet that powers the radio has a HOT wire, and a NEUTRAL wire. The transformer provides “galvanic isolation” which effectively isolates the internal electronics from the power lines, such that the user could not be shocked by the radio as long as he did not touch the stuff INSIDE the radio. The house current was fed to a transformer (often called the power transformer) which converted the 110 volt house power to lower voltages which powered the tubes. In the 1930's, radios became available that ran from house current. In the early days of radio (1920's) most of them ran on batteries, as many homes and farms did not have electricity, especially in rural areas. I doubt that too many people would intentionally grab onto a metal object and stick it into the wall outlet while otherwise grounding themselves, however this is EXACTLY the scenario that can occur in one of three ways with our vintage electronic equipment. This can also be true of the ground outside, damp wood, or other surfaces. SO, to repeat touching a live (connected to power line HOT, even if through some electronic parts) circuit while standing on concrete with bare feet, or leaning against a concrete or steel wall can cause a serious or possibly fatal electric shock. Concrete, and cement based flooring (Terrazzo was the source of many shocks, some serious, during my childhood) contains enough trapped moisture to conduct enough electricity to cause a lethal electric shock. What is not obvious are some sources of unintentional grounding. For example many plumbing fixtures are grounded through copper plumbing. Many metal objects in the home are intentionally grounded and some are grounded due to the way that they were built or installed. This means that touching the HOT wire from the electrical outlet while simultaneously touching ANY grounded object will deliver a potentially lethal electric shock, just as if the person were to touch both the HOT and NEUTRAL wires. In many areas there is a connection from NEUTRAL to GROUND at the fuse or breaker panel. There is also a ground wire on nearly every power pole, reinforcing this ground system. In North America the NEUTRAL wire is connected or “bonded” to the metal water pipes in most buildings, or other conductive material that is buried in the ground. The power system in most countries is connected to an earth ground for protection against lightning and accidental short circuits between 120 volt house current and high voltage distribution lines, say when a car hits a power pole and wires touch each other.
#AIRLINE GUITAR AMP SCHEMATIC HOW TO#
Let’s explore all three, and discuss how to make these old electronic devices safe to use. There are three ways that a vintage piece of electronic equipment can kill you, one or two of them are likely present in nearly ALL electronics made before 1970. So, yes your vintage amp, HiFi, guitar or PA can KILL YOU DEAD!!!! These are just the players famous enough to get written up in a major publication. Searching for "guitar player electrocuted" will bring up a few more names, notably Keith Relf of the Yardbirds. I suggest the searching by manufacturer to get to the right part of the page.So, what is a "Death Cap" and can my vintage guitar of HiFi amp really kill me?Ī quick Google search with band name "Stone the Crows" will tell you that their lead guitar player, Les Harvey was electrocuted on stage before a live audience in 1973 due to a malfunction in his guitar amp when he touched a grounded microphone. It’s all laid out in a very large, 1-page table. This page has a lot of guitar amplifier and distortion pedal schematics on it.
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