Help on what transistor use in cathode row in LED matrix

[cuber18]

can you help what transistor should i connect to a cathode row? and what resistors should i use? my led matrix row is connected with a 74ls154 IC w/c output is active low..

 

[mishra12]

the value of resister depends upon led quantity

 

[cuber18]

im creating a 14x40 led display.. w/c is 14rows and 40 columns. am i on the right track having my rows connected to a PNP transistor?

 

[mishra12]

you can use value 47 ohms

---------- Post added at 16:53 ---------- Previous post was at 16:52 ----------

less than 47 is better because your row is 14

 

[cuber18]

im using 110ohms in my base.. my collector is connected to the ground and my emitter is connected to the row of my led matrix.. my base is connected to the output of my 74ls154.. is my design correct? and where should i connect the 47 ohms resistor?

 

[mishra12]

for base 1k -10k ohm resister and for after collector and led 47 ohms

 

[cuber18]

my collector is in ground.. how about my emitter?

 

[mishra12]

can you post circuit diagram,row scanning or column scanning

 

[cuber18]

you can use sk100 pnp transistor

---------- Post added at 16:59 ---------- Previous post was at 16:58 ----------

can you post circuit diagram


---------- Post added at 17:00 ---------- Previous post was at 16:59 ----------

row scanning or column scanning method ?

---------- Post added at 17:12 ---------- Previous post was at 17:00 ----------

wait a minute since you are using cathode row you should use 40 npn transistors for column

im using tip147 transitor in my row.. and 74hc595 in my columns? should i use transistors in my columns? whats the connection of my tip147? base in 74ls154 output? and collector to led matrix row? and emitter to the ground? am i correct?