1. Home
  2. Hobby Electronics Basics
  3. Spike!

Spike!

Greetings,

I read an article on a transformer test recently where the term "spike" was used. I didn't give it much thought then but, It stuck in my mind because the last few words in the article contained: "Be careful when you turn it off, there's a huge spike..."

I recall discussions on Inductors and how they release thier energy back toward the source but, in this case, once the circuit is broken, how do the coil/coils discharge? Is the spike fired back into the mains or into other circuits in the panel? Is this a source of "Noise"?

Randy

Reply to
Randy Gross
Loading thread data ...

Any inductance has the following relationship between current and voltage:

V=L*(di/dt) Or the voltage (volts) across the inductor is proportional to the time rate of change of the current through it (amps per second). The inductance (in henries is the constant of proportionality. If a transformer or other inductor is connected to an AC source, and happens to be switched off (I goes toward zero very fast) at the moment when the current happened to be quite large, the voltage produces can be very high. This is the spike they are talking about. This is the same process used to produce sparks from an ignition coil.

If you measure the resistance of a transformer with an ohm meter and disconnect it while your fingers touch both sides of circuit break, the transformer may produce enough voltage that the small current built up by the ohm meter may be pushed through your fingers and give you a small shock.

--
John Popelish
Reply to
John Popelish

These are sobering statements. From knowledge gathered from this group and books on basic electricity, I have reconfigured and tested many transformers and overlooked one basic fact about them, they are inductors and capable of delivering a vicious bite when they are turned off. I've been lucky!!

I try to conduct all of my experiments safely, for myself and those around me. What safeguards can I institute to guard against an accidental encounter?

Reply to
Randy Gross

an acidental encounter is an accident, cannot always be avoided when experimenting... ..... unless you begin building protetion circuits before experimenting, but i wonder what real techie always does that at least i've never seen one do it in over 24 years

These are sobering statements. From knowledge gathered from this group and books on basic electricity, I have reconfigured and tested many transformers and overlooked one basic fact about them, they are inductors and capable of delivering a vicious bite when they are turned off. I've been lucky!!

I try to conduct all of my experiments safely, for myself and those around me. What safeguards can I institute to guard against an accidental encounter?

Reply to
peterken

don't work drunk; don't work tired. Keep one hand in your back pocket at all times; eclectricy and water don't mix; don't stand in puddles; low voltages at *high* currents are just as dangerous; remove all metallic jewelry.... And more? I'm sure there are! Bring'em on...

--

Fat, sugar, salt, beer: the four essentials for a healthy diet.
Reply to
Steve Evans

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.