In my application, I should control 4 display composed of 7 segments. I want to use a classic method with 4 BJT and segments all driven by a Micro. An update rate will show up each value on the powered display.
Particularly is that I'd like to have the possibility to interchange between Common anode screen and Common Cathode.
Is there an optimized or right way to do that?
Test I've done: - Two BJT, single gate, single resistor; - Single BJT with inverting lines using jumpers;
I'll post some images in some hours, but despite my schematics. How do you advise to proceed?
Here's my BJT tests, power supply is a single buck regulator that regulates form 24v to 5v. There's a resistor on each port that goes from my Micro (PIC16F15354) on a single segment bus.
In the Test 1, all were fine, I've tested both CA and CC displays without problems, One were brighter than other because a voltage drop on BJT when used with LEDs between emitter and ground. I measure a voltage of 5v on my gate.
In the Test 2, no leds lights on, I've tried to measure voltage and I see 0.8v on each BJT gate.
What is wrong?