Re: Morse tutor
¿ªÔÆÌåÓýThanks Bruce. Good information. On my displays, there is a driver transistor, Q1, a J3Y = S8050, with a 1k resistor at the base, and the other end of the resistor to the LED pin. So that must be the componenets you refer to. I haven¡¯t downloaded you new BP program yet, so I don¡¯t know the PWM pin number. But that, I¡¯m sure, could be seen in the program or in another of the GitHub files. ? OZ1QZ / John ? Sendt fra til Windows 10 ? Fra: Bruce Hall ? Hello John, ? Nice to hear from you again! ? I have all of the software on GitHub.? I updated the software for the 'old' tutor,?which is here: ? The display updates will work on your old STM32 device, except for backlight control.? ? I have not updated the ESP32 code yet. ? For backlight control, the?old tutor requires a hardware change.? The first step in the procedure is to look at the back of the display pcb, where the components are mounted, and determine if there is a driver transistor for the backlight circuit.? It will consist of a 3-pin transistor (SOT23 package) and adjacent 1K resistor.? I have discovered that some displays have this driver.? Other displays connect the backlight LEDs directly to the backlight pin.? If you need help locating this transistor I can send you a photo of it. ? The new code controls the backlight by varying the duty cycle of a PWM signal.? ?If there is a transistor driver, we can solder a single wire from the PWM signal to the backlight pin and we are done.? ?If there is no transistor driver on-board, the backlight current (about 90mA) is too much for the.microcontroller to handle.? ?In that case we would need to add our?own transistor driver.? ?The pocket tutor pcb has a transistor driver, which can be bypassed if not needed. ? Does that help at all?? ? ? Bruce ? On Sun, Jul 19, 2020 at 5:37 AM John Kristiansen <john.k@...> wrote:
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