Greetings to All: There are RF mixers such as the SBL-1 which works well in the MHz range. I am interested in mixing 25KHz with 20KHz to get 5KHz and 45KHz such that I can hear the difference thru an amp & spkr. Does anyone have any ideas as to what to use for an ultrasonic mixer? Thank you 4 your time & attention.
The mixer can be air. MIT gave an award for the invention of the year around 2005 : Two ultrasonic loudspeakers send 20khz and 25khz airwaves to a point where they converge. People cannot hear either ultrasound, but the non-linear aspects of air cause a mixing of the two inaudible signals and people can sit at the point of convergence and hear the 5khz sound!!! No electronic mixer is needed, just ultrasound and air !!!!!!!!!
I independently invented this in 1987, but did not publish it. Imagine how a halloween ghost voice could be used to haunt a paranoid rival ! Ha ha.
***************************************************** I'm sorry ! I have absolutely no clue what this list of #s means and/or what it is used for fredander
*************************************************************************** I'm sorry! I did not mean to cause any problems. I apologize! ! ! I will try not to ask any more questions of this forum. fredander
LTSpice is available, free, from the Linear Technology website. Download and install it, copy the lines of the newsgroup article (from "Version 4" thru the last "TEXT" line) into any old text editor, and save it as, say, "jfields_mixer.asc", then start LTSpice, and open your saved .asc file there.
John's schematic should appear before your eyes, and you can run analyses on it, plot waveforms, and edit the schematic.
LTSpice is becoming the de facto standard for exchanging, comparing, and discussing circuit suggestions on sci.electronics newsgroups, principally because its source files are pure ASCII text.
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
If your signals are pure sinewaves, a good mixer is a multiplier circuit (F1 and F2 inputs give an output that has (F1+F2) and |F1-F2| frequencies). If, on the other hand, your signals are squarewaves, like from a simple NE555 type oscillator, all it takes is an XOR gate, like (in CMOS through-hole package) CD4030 or CD4077. A dollar will buy you two, each has four XOR gates.
The range of analog mixers is large, and includes almost all nonlinear electronic parts: diodes, transistors, FETs. With some care in design, any of these can mix down ultrasound. The MiniCircuits mixers are based on matched diodes, Gilbert cells use matched transistors (usually in integrated circuit form). These cover more RF range than you need. One can wire the LM13700 into two multiplier circuits, and that's about a dollar.
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