Using UDN2981 instead of ULN2803

MIDIfication
1

Hello to everyone

This is my first post to the forum. My project is pipe organ midification (More about the organ later. Let’s get something working first). I have a working core and MIDIO128 using ULN2803’s. But, like several others, I have positive keying. Reading the forum directed me to the UDN2981, but these devices do not work in the DOUT’s. I have the + and - connected as shown in the UDN data sheet. One forum post stated the the DOUT boards will not work with the UDN’s and Trevor, in one of his posts, mentioned “swapping pins 9 and 10”. Has anyone successfully used UDN’s, and if so, how should I proceed?

Thanks

Al Earhart

Kilgen Opus 3972 theatre pipe organ

2

The two chips have the same pinouts EXCEPT that the power supply pins are reversed. 

If you can solder jumper wires, you may be able to get around this or use lots of stripboard and connectors.

Outputs of DOuts go to inputs of driver chips, output to the magnets of the pipes.

HTH

Sparx