Single Inversion Discrete Circuit

[jollyrgr]

Back many years ago (early 1980's) I played around with single inversion frequency circuits. Not the single IC type that seem to be everywhere but the audio amp, oscillator, and four diodes. But I cannot recall how the diodes were arranged and the connections to the diodes were made.<p>If I recall correctly, the four diodes were connected such that they were all connected ANODE to CATHODE in a "ring" configuration. The two audio lines were then connected to two oposite corners of the four diodes. The frequency oscillator was then connected to the remaining two corners. Is this correct?

[MrAl]

Hello there,<p>IF you are talking about rectifying an audio
output into dc, then you do the following:<p>Connect a pair of diodes with cathodes connected.
Connect another pair with anodes connected.
You then connect the two pairs together by
connecting their unconnected leads to the
opposite pairs' unconnected leads, which when
layed down on a table top will then look like
a 'square' or 'diamond' shape with a diode
on each side, with four points for external
connections.<p>
The external connections are then as follows:<p>The connection of anodes is the (-) output,
the connection of cathodes is the (+) output.
The two remaining connections are the audio
input leads, polarity doesnt matter.<p>IF this isnt what you were talking about,
then perhaps you can explain a little more
what it is you are trying to do. I assumed
you were using an audio amplifier to create
a dc voltage converter.<p>
Take care for now,
Al<p>[ September 12, 2003: Message edited by: MrAl ]</p>

[Dave Dixon]

That sure seems correct to me. (90 per cent
sure at least) I remember building one in the
80's to listen in on the detectives who used
it on the police band! Those were the good
'ole days!!
Good luck,
Dave

[Ron H]

I think you mean single CONVERSION, not inversion. Your description sounds like an RF modulator, using a diode ring as the mixer. I thing of single conversion as generating the IF signal in a receiver, where the RF signal from the antenna is mixed with the local oscillator, and the outout of the mixer is the IF (intermediate frequency) signal.

[jollyrgr]

Thanks to all who responded.<p>Mr. Al. What you are describing is a full wave bridge rectifier and I know how to make those. <p>Dave Dixon<p>You and I are on the same track. My local police used this method throughout the eighties. I built one of these in high school electronics to decode the "scrambled" signal thinking I was missing interesting things. I had a schematic from "scramble" phones from the OLD OLD Popular Electronics. I perfboarded the diode section and used a cassette player (with recorded scrambled audio from a scanner) as the source. The oscillator was a bench signal generator. I was highly disappointed when the most interesting thing they discussed in "scramble" mode was where to meet for lunch!<p>RonH
Yes, I do mean INVERSION as in SPEECH INVERSION. I know about single and dual conversion in radio receivers. I believe that this is also called a BALANCED MODULATOR as those used with single side band transmitters. The scrambled audio sounds very much like listening to a SSB signal on the wrong sideband. <p>Here is a website that sells kits, one of them a voice scrambler:<p>http://members.aol.com/ctpds49/<p>Below the picture of the parts kit of the portable unit is a link to hear the audio of one of these scramblers.

[MrAl]

Hello there,<p>Sorry 'bout that
I realized you might have been talking about the
other type after reading RonH's post.<p>Good luck with it,
Al

[Edd]

Yep, still sounds like you were utilizing a ring modulator or demodulator, in accordance to its configuration. Making speech inversion in the AF spectrum.
Your referenced site only depicted circuit information, as close as a PCB layout, where one could see the utilization of ~ two discrete bipolars and two IC’s on its layout , no schematic info.
Here’s a comparable circuit that does afford some degree of circuit hook up isolation by virtue of transformer isolation.
REF:
http://home.maine.rr.com/randylinscott/oct99.htm <p>73's de Edd
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