From: Alan Womack <arwbackup@wo...> - 2002-11-30 04:37:30
ok, "I" have the circuit working thanks to Butch's feedback on how to set the =
potentiometer. I think if I hooked it up to the PP port it might work =
Now I need to make a tweak with some assistance for the ibutton. My output on =
pin 7, with the potetiometer tweaked just so is 2.27 volts. When I hit the =
photo cell the output drops to under 1 volt.
If I tweak the pot to bring pin 7 high to 6.3 volts, I then can shine the =
pointer to drop to just over 5 volts. I supposed if I drop my power supply =
voltage down some more, I could get a below 5 volt supply when the pointer is =
I need to change my output from being high, dropped low, to being low brought =
high so that the DS1994 iButton will register the over 5v condition as a pulse.
What changes do I need to make to the circuit for this? The iButton needs to =
see a low signal inorder for the bus to be read by the DS9097U.
Well to change the output direction you should only have to swap pins 5 =
and 6 so that the output stage operates as an inverter. However from =
your description it is not operating as I expected ( I expected the =
output to go high when the light was shone on the sensor) so I may be =
wrong on this. Perhaps someone else can explain it to me. Could the IC =
The other way of changing it is to swap over the sensor and the 10k =
Also it is not really meant to drive a LED, so it might be an idea to =
increase the LED resistor to 1k which will make your output low lower.
Alan Womack wrote,
>I need to change my output from being high, dropped low, to being low =
>high so that the DS1994 iButton will register the over 5v condition as =
>What changes do I need to make to the circuit for this? The iButton =
>see a low signal inorder for the bus to be read by the DS9097U.