I did the same thing using small 6 electrolitic caps which connected as parallel to base pin of driver transistor and ground path. But non adjustable for tail lighting effect.
Each these 12V LED strips draw 100 to 150mA of current. The maximum current of BC547 is 100mA and not enough. Also the pin configuration of BC547 is different compared to BD139. So it is not a good replacement. You can use BD135, BD137, D400, C2383 to replace BD139.
Mata me wage circuit ekk hadaganna one me wage led segment 20kin.mata puluwan nm help ekk denawada.circuit diagram ekk denna puluwanda e wage circui ekaka
You can download its datasheet with circuit diagram and specifications here 👉 datasheet.lcsc.com/lcsc/1809131811_Jiaxing-Heroic-Elec-Tech-HT8691_C97638.pdf
Nice circuit using 3 LED's per light. I used a PWM module in mine to be able to dim certain LED's in order to get the tail. Here's mine. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-gmc_PM1_iro.html
@@hobbyelectroniccircuits7391 Thanks. It took me 2 1/2 years to make the software, PCB Maker, by NewRAD. And then about 35 minutes to mill the board with my CNC machine. But I did it for about $2. PCB Way wanted to charge me $48 for a board that big, and take 3 to 7 days. To do it in 35 minutes for $2, and with the added benefit of not having to use their software, or upload Gerber files, or use their website. To avoid all of that mess is priceless.