Differences between version 4 and predecessor to the previous major change of Adding 4th, 5th, and 6th Harmonic Percussion.

Other diffs: Previous Revision, Previous Author

Newer page: version 4 Last edited on January 19, 2012 5:44 am. by
Older page: version 2 Last edited on April 24, 2011 2:59 pm. by
@@ -1,8 +1,8 @@
 Adding the 4th, 5th, and 6th Harmonic to the Hammond (B3, C3, RT3, or A100) Percussion allows for much more percussion variation by making 3 more harmonics available in addition to the 2nd and 3rd standard harmonics. With the first 3 drawbars out (the usual setup) there is much more contrast between the drawbar setting and the percussion tones. The sharp percussive bite is now available much lower on the keyboard. To get the full effect of this harmonic addition EliminatingThePercussionVolumeDrop is very desirable since this will restore full volume control to the drawbar settings. Two miniature, four pole switches (one for the percussion on/off and one for the 4th, 5th, 6th harmonic selection) and some stranded hook up wire is all that is needed. The switches are available from Mouser electronics (part No.’s below). Note with this design, the 4th, 5th, and 6th harmonics are not available at the drawbars when the percussion is on. The usual percussion setting is some combination of the first three drawbars so this shouldn't be a problem. 
  
 <br> 
-__DESIGN SCHEMATIC__ 
+__DESIGN SCHEMATIC--TWO SWITCHES FOR HARMONIC SELECTION __ 
 <verbatim> 
 The schematic below shows the switches S1, S2 and the associated hookup to the 
 AO28 preamplifier and the drawbars. 
 S1 is shown in the ON state and S2 is shown DOWN with the 4th harmonic selected. 
@@ -96,6 +96,54 @@
  
 <br> 
 __ADDED BONUS---ParadiseButton FOR 4th, 5th and 6th HARMONIC PERCUSSION__<br> 
 The B3 percussion switch must be on for the 4th, 5th and 6th harmonics to work. When the B3 percussion switch is off, you automatically go into the ParadiseButton mode for the 4th, 5th and 6th Harmonics. In this mode the percussion will not decay and the 4th, 5th and 6th harmonics (depending on the selection of S2) will sound much louder. If the ParadiseButton mode is not desired, just turn off S1. 
+  
+!—JohnMihevic  
+------  
+The 4th, 5th , 6th percussion harmonic selection described above uses two switches. Below is a description using three switches. The wiring concept is simpler and multiple harmonics can be selected for percussion.  
+  
+<br>  
+__DESIGN SCHEMATIC--THREE SWITCHES FOR HARMONIC SELECTION__  
+  
+<verbatim>  
+The schematic below shows three switches S4, S5 and S6 for harmonic selection.  
+  
+S5 is shown in the ON state with the 5th harmonic selected.  
+S4 and S6 are shown in the OFF state.  
+  
+ |------|----------|-----------|  
+ | | | |  
+ | | | |  
+ | . /.-| .\ .--| . /.-|  
+ | S4-1/ | \S5-1 | S6-1/ |  
+ | . | . | . |  
+ | | | | | | |  
+ | | | | | | |  
+ | DB6W DB6 DB7W DB7 DB8W DB8  
+ | 4th Harm 5th Harm 6th Harm  
+ |  
+ |  
+ | . /.-| .\ .--| . /.-|  
+ | S4-2/ \S5-2 | S6-2/ |  
+ |--------. | . | . |  
+ | | | | | |  
+ | | | | |  
+ | |------| |-----| |  
+ | |  
+ H HW  
+  
+S4 4th harmonic DPDT On/Off switch; Mouser Part No. 633-M202201-RO  
+S5 5th harmonic DPDT On/Off switch; Mouser Part No. 633-M202201-RO  
+S6 6th harmonic DPDT On/Off switch; Mouser Part No. 633-M202201-RO  
+  
+Other descriptors (H, HW, DB6, DB6W, etc.) are as described above.  
+</verbatim>  
+<br>  
+__THEORY OF OPERATION__<br>  
+  
+The “1” set of contacts on the S4, S5 and S6 selects the appropriate harmonic from the drawbar wire and routes it to the “H” (percussion input on AO-28) terminal. The “2” set of contacts are wired in series to isolate “HW” from terminal “H” anytime a harmonic is selected. “HW” comes from the percussion switchbox for 2nd or 3rd harmonic input to the AO-28 when none of the harmonics (4th, 5th or 6th) is selected.  
+  
+An additional feature of the three switch configuration is that harmonics can be combined, i.e; 4&5, 4&6, 5&6 and 4&5&6.  
+  
  
 !—JohnMihevic 

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