Warning about Mr. Thumpy!
As of 10/02/97, this page contains TWO warnings about the Radio Shack Thumper
device. One is concerned about lethal voltages, the other about mercury
poisoning from fillings.
Date: Sun, 24 Aug 1997 22:43:02 -0700
Subject: Re: Thumpy----Please read this!
I just browsed through the Mr Thumpy article, and I'm very concerned about the
potential for electrocution. Please let me explain:
Typically, 35mm strobes feature an oscillator driving a small transformer to
step up battery voltages to the hundreds of volts necessary to charge the
The flash capacitor is connected to the strobe tube, but cannot light it
unless the trace gas in the tube is ionized.
To accomplish this, part of the of the flash cap charged is dumped into a
trigger coil which produces about 4kv or so to ionize the tube.
Once the tube starts conducting, the flash capacitor dumps its remaining
charge directly into the strobe tube.
Personally, I wouldn't want to be "thumped", either with the 4kv trigger
voltage (which would probably hurt like hell) or the flash capacitor voltage
(which could actually burn you.) But this is NOT why I wrote you.
Later in the article, the author talks about his enhanced "thumper" made from
a party strobe sold by Radio Shack.
If this strobe is the unit I am thinking of, DO NOT DO IT! If the strobe is
the unit I think it is, the flash capacitor is NOT charged with a battery-
powered oscillator, but is instead charged directly from the 110v main!
If you expose yourself to any of the components inside of the strobe, you are
running the risk of shorting the utility main to ground THROUGH YOUR BODY, and
exposing yourself to a profound ELECTROCUTION HAZARD.
I fear that some idiot will end up killing himself. The last thing we all need
is a reason for big brother to start regulating internet content. Do everyone
a favor and take that piece of "science" off of your web page.
...A concerned reader...
Date: Thu, 02 Oct 1997 15:50:20 -0600
From: Malina Schindel
To: Jerry Decker
Subject: Mr. Thumpy
I feel compelled to add my own warning to the Mr thumpy files. The magnetic
impulse of this device is very similar to induction hardening of tools.
This technique uses a heavy magnetic pulse to heat the surface of steel which
momentarilly melts and rehardens.
If you use Mr thumpy next to gold crowns or mercury amalgum filings, the
thermal shock is going to knock them loose and may free mercury to be
From a friendly regular reader of your website.