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Conference napalm::commusic_v1

Title:* * Computer Music, MIDI, and Related Topics * *
Notice:Conference has been write-locked. Use new version.
Moderator:DYPSS1::SCHAFER
Created:Thu Feb 20 1986
Last Modified:Mon Aug 29 1994
Last Successful Update:Fri Jun 06 1997
Number of topics:2852
Total number of notes:33157

2707.0. "phase-inverter" by HEART::MACHIN () Tue Aug 27 1991 16:30


	Anyone know of a device, or plans for building a device,
	that inverts the phase of an audio signal?

	I saw one used in a stuidio once (compensated for delay induced
	by long cables) but I think it was home-made.

	Ta

	Richard.
T.RTitleUserPersonal
Name
DateLines
2707.1Do it yourself...CSC32::MOLLERFix it before it breaksTue Aug 27 1991 17:0937
				
     Using Radio Shack parts. this should set you back about $5.00

						47k
				       +------/\/\-------+
				       |                 |
				       |  |\   |V+       |
	    In	    + 10uf       47k   |  |  \ |         |
		0-----||---+-----/\/\--+--| -  \         |
		           |              |      \       | + 10 uf
	        >- gnd     |              |        >-----+--||----0  out
                           /              |      /
                           \ 1 meg    +---| +  /	  gnd   -->
                           /          |   |  / |	
                           \          /   |/   |V-
                           |          \ 47k
			   gnd        /
				      \
				      |
				      gnd


	Use the TLO82 chip (2 op amp's per 8 pin chip) & make 2. You could use
	2 9 volt batteries to drive this:

			       gnd
				|
		+ ------+   +---+---+   +------ -
			|   |       |   | 
			
			+   -       +   -

			  9V          9V


	It's a very simple unity gain inverter with about 50K input 
	impeadance.
2707.2HEART::MACHINWed Aug 28 1991 10:0410

	Thank you -- just what I needed. I'm not at all handy
	with a soldering-iron, but for a fiver I reckon it's worth
	a go. 

	Incidentally, could you stick a variablr resistor in here
	somewhee to vary the phase shift a bit either side?

	Richard. (ready to get his fingers burnt)
2707.3RGB::ROSTFart Fig NewtonWed Aug 28 1991 11:4510
    Re: .2
    
    No, you can't vary the phase shift, it's a solid 180 degrees.
    
    BTW, for those using balanced XLR lines, you can get 180 degree phase
    shifting by simply reversing the connections to pins 1 and 2 on the
    cable, no circuit needed.  
    
    
    							Brian
2707.4HEART::MACHINTue Sep 03 1991 10:238

	Many thanks for the diagram -- it works fine!

	And the pound-sterling cost was LESS THAN THE DOLLAR
	COST (i.e. 3.40). Is this a record? (No -- just a phjase-inverter).

	Richard.
2707.5KERNEL::IMBIERSKIThu Sep 05 1991 08:259
2707.6HEART::MACHINThu Sep 05 1991 10:256

	Well, it was just that with every other piece of electronic
	music gadgetry I've bought, pound = dollar or less.

	Richard.
2707.7QUIVER::PICKETTDavid - Live free or live in Mass.Thu Sep 05 1991 18:205
    From our end: pounds = 1.6(dollars) The conversion changes daily. The
    1.6 is a rough approximation of recent exchange rates.
    
    dp