J
Jon Danniken
- Jan 1, 1970
- 0
Hi, I am trying to take advantage of an extra flip/flop output in an
existing circuit. The driving signal is either 0V or +5V, but the emitter
voltage (to drive the switched load) is +18V.
This is the circuit I am planning to use:
+18V
|
Rb |
___ |/
On=0V ---|___|-----| PNP
Off=5V |<
\
|
.-.
| | Load (15mA)
| |
'-'
|
|
===
GND
I am going to try getting the base resistor to be such at the transistor is
off when the IC is at 5 VDC, and on when the IC is at 0 volts.
Besides fiddling with the base resistor, is there a different topology, or
modification I can make to the existing one to make this work better?
I do realize that putting an NPN transistor off of the IC's output would
solve this nicely, but space is at a premium, and I would like to do this
with just the one transistor.
Any ideas?
Thanks,
Jon
existing circuit. The driving signal is either 0V or +5V, but the emitter
voltage (to drive the switched load) is +18V.
This is the circuit I am planning to use:
+18V
|
Rb |
___ |/
On=0V ---|___|-----| PNP
Off=5V |<
\
|
.-.
| | Load (15mA)
| |
'-'
|
|
===
GND
I am going to try getting the base resistor to be such at the transistor is
off when the IC is at 5 VDC, and on when the IC is at 0 volts.
Besides fiddling with the base resistor, is there a different topology, or
modification I can make to the existing one to make this work better?
I do realize that putting an NPN transistor off of the IC's output would
solve this nicely, but space is at a premium, and I would like to do this
with just the one transistor.
Any ideas?
Thanks,
Jon