Re: Bridge Pinger with one side grounded?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jan Wagner by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jwagner-at-cc.hut.fi>

Hi!

On Mon, 9 Dec 2002, Tesla list wrote:
 > Original poster: "Jolyon Vater Cox by way of Terry Fritz 
<twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
 > Is it possible to build a ping tester with a bridge output where one side
 > of the bridge is grounded?
 > I am thinking of adding another 555 to my 555 astable pinger to act as a
 > phase inverter to get a squarewave (between Pins 3 of the two ICs) of twice
 > the voltage of the 555 astable alone.

Like, the first 555 output jumps 0V 12V, which serves as ground for the
second one? So the final output consists of 0V..12V..24V steps?
Unusual, but, well, why not... :)

OTOH, for this you'd have to precisely sync the two 555s somehow,
otherwise you'll end up with an odd beat envelope and unwanted frequency
content on the output which may, or may not, completely mess up your
measurement. Probably requires a comparator and schmitt trigger in the
upper section, no 555, to prevent sync probs.

IMO much simpler would be if you get a small ferrite toroidal
core from somewhere (junk box?), slap a few 10 turns of enameled copper
wire through it for a primary, and twice those turns on the secondary.
One primary and one secondary end grounded. Loose pri end via 1uF
non-polar poly-something cap (FKP/MKP pulse cap) to the 555 section
output.
This gives you twice the output voltage but at the expense of twice the
input supply current.

cheers,
  - Jan

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  Jan OH2GHR