component-selectiontransistors
I found a one pulse activated automatic trigger circuit and it has A509 and C509 Transistors to be used.
But, these transistors are extremely rare and very hard to find.
eBay has those both, but it is not worth to buy according to huge import charges and shipping fees.
Circuit Diagram:
Please can you recommend best equivalent transistors for A509 PNP and C509 NPN Transistors?
To be as close to the original equipment, I recommend that you should buy the replacement transistor from ebay, it is not that expensive. As you are not greedy, the price should be ok and you get the joy of replacing it yourself.
Joy of fixing your own charger is priceless. Happy holidays.
Your circuit concept is starting in the right direction but it requires some important changes for it to work.
You will require series base resistors for all of the PNP transistors. As drawn you will cook them with no base current limitation.
Secondly the NPN transistor is drawn backwards. Its emitter needs to connect to the GND.
Third you need to do some serious work reorganizing the way the bases of the various transistor are biased. You need to separate the 12V and 5V PNP bases so that the 12V one can shut off when the base drive goes away to the 5V one. After this fix it is necessary to provide also a separate pullup of the NPN transistor.
Don't cringe. Resistors are incredibly cheap.
Lastly this schematic, to be bluntly honest with you, is horribly drawn being that it does a bad job of following conventional standards for how a good schematic is drawn.
Best Answer
Pretty much any el cheapo transistor will do. Don't pick the fancy types.