OK, that's not a very clear subject. The ULN2803A has 8 inputs to the base and 8 open collector outputs, with the emitters tied together and grounded.
What I'm wondering is if there is something similar with 8 base inputs and 8 *emitter* outputs, with the collectors tied together and connected to the positive rail.
I've made an 8-digit 14-segment display; it works a treat, but uses 8 discrete transistors for selecting the individual display. So I thought it might be neater to use a driver chip. Actually it just occurs to me that a 3-8 multiplexer would do the trick and also reduce the port pins needed from 8 to 3, but in any case I'd still like to know if such a device exists.
Project photo attached. No circuit diagram available, brief explanation: PORTA 0-3 and PORTB 0-3 select the individual display via the transistors, the display outputs are tied together and routed through a resistor array and 2 ULN2803A's, and PORTC 0-7 and PORTD 0-6 control the segments.
What I'm wondering is if there is something similar with 8 base inputs and 8 *emitter* outputs, with the collectors tied together and connected to the positive rail.
I've made an 8-digit 14-segment display; it works a treat, but uses 8 discrete transistors for selecting the individual display. So I thought it might be neater to use a driver chip. Actually it just occurs to me that a 3-8 multiplexer would do the trick and also reduce the port pins needed from 8 to 3, but in any case I'd still like to know if such a device exists.
Project photo attached. No circuit diagram available, brief explanation: PORTA 0-3 and PORTB 0-3 select the individual display via the transistors, the display outputs are tied together and routed through a resistor array and 2 ULN2803A's, and PORTC 0-7 and PORTD 0-6 control the segments.
