Re: ... notes and drawbarsettings randomly changing
Verfasst: 28. Feb 2016, 16:23
TRICKY WAY TO REALIZE A//B SWITCHING with ONE WAY SWITCH
Normally with unsoldered resistor R 22 ( 22 K ) You can switch with a TWO WAY SWITCH connected on PL 43 between Drawbar Set A or B
The relevant pins 9,10,11 of the IC´s 74 HC 4053 are then switched between + 3,3 Volt and GND
But with a switch with only one way the second opinion normally is missed.
But the now obsolet R 22 can do us a favour.
When connecting this resistor from pins 9,10,and 11 direct to pin 16 of the 74 HC 4053 the internally switches in these IC´s are switched in one direction. The value of this resistor is high enough to set the pins 9.10,11 to logic high level = 3,3 volt and in second to make no trouble when the pins 9,10,11 are connected to GND too. The function of the resistor R 22 is only a PULLUP RESISTOR nothing else.
So with this tricky way a simple ONE-WAY-SWITCH can be used to realize proper changing of sets A or B of drawbars
The third cable of plug 43 ( connected to + 3,3 volt ) is then obsolete . please isolate it or cut it.
The only thing to do now is the position of the one way switch to mark the direction of wanted drawbar set. If You want it reverse just turn the switch in mounting position.
If there is no way to change mounting position of one way switch ( perhaps used switches from Hammond panel ) it is also possible to change the resistor from PULLUP-function to a PULLDOWN- function
In this case pins 9,10,11 of IC´s 74 HC 4053 must be connected via the resistor 22 K to GND. The function of the resistor is now PULLDOWN .
The internal switches in the 74 HC 4053 will change to opposite switching position because they "see" LOW level via the PULLDOWN resistor.
In case of this now the real oneway-switch must close the middle Contact = A // B to + 3,3 volt to get the other Drawbarset. In the "mode" PULLDOWN of the resistor the cable GND is obsolete and must be isolated or cut
Normally with unsoldered resistor R 22 ( 22 K ) You can switch with a TWO WAY SWITCH connected on PL 43 between Drawbar Set A or B
The relevant pins 9,10,11 of the IC´s 74 HC 4053 are then switched between + 3,3 Volt and GND
But with a switch with only one way the second opinion normally is missed.
But the now obsolet R 22 can do us a favour.
When connecting this resistor from pins 9,10,and 11 direct to pin 16 of the 74 HC 4053 the internally switches in these IC´s are switched in one direction. The value of this resistor is high enough to set the pins 9.10,11 to logic high level = 3,3 volt and in second to make no trouble when the pins 9,10,11 are connected to GND too. The function of the resistor R 22 is only a PULLUP RESISTOR nothing else.
So with this tricky way a simple ONE-WAY-SWITCH can be used to realize proper changing of sets A or B of drawbars
The third cable of plug 43 ( connected to + 3,3 volt ) is then obsolete . please isolate it or cut it.
The only thing to do now is the position of the one way switch to mark the direction of wanted drawbar set. If You want it reverse just turn the switch in mounting position.
If there is no way to change mounting position of one way switch ( perhaps used switches from Hammond panel ) it is also possible to change the resistor from PULLUP-function to a PULLDOWN- function
In this case pins 9,10,11 of IC´s 74 HC 4053 must be connected via the resistor 22 K to GND. The function of the resistor is now PULLDOWN .
The internal switches in the 74 HC 4053 will change to opposite switching position because they "see" LOW level via the PULLDOWN resistor.
In case of this now the real oneway-switch must close the middle Contact = A // B to + 3,3 volt to get the other Drawbarset. In the "mode" PULLDOWN of the resistor the cable GND is obsolete and must be isolated or cut