24 Jan 2020 22:17 #1
I do have a question now. TR1 and TR2 on the FK112 are listed as two SC458 NPN transistors, But my kit includes two SC1815 NPNs. But also I see SC1815 is listed as an alternative transistor on your sheet. SC458 is drawn from the front drawing as ECB, but when I look at SC1815 drawings, the front view seems to be BCE. I'm not sure if I have to reverse the pins, so that they are the opposite of the D shape drawn on the circuit board.
I notice that the emitters of the C458s connects to GROUND, the bases to either R1 or R2, and the collectors to either R3 & R4 or R5 & R6.
I quess it is different with the SC1815s. It might be best to show me a new circuit diagram, to make sure I get it right :-) Email me that if you can please.
Thanks for any advice available!
26 Jan 2020 22:51 #2
Well, I decided to proceed with using the alternative transistors in the orientation shown on the kit leaflet. I got the flasher to work, and it is also setable with the pot.
But now another slight problem: only one red LED and two green LEDs are actually working. This might be due to my rather clumsy soldering style, but it looks like it is partly due to one red LED either being damaged or of a higher resistance to the other red LEDs in the set. The good thing is i am actually learning something from my clumsiness and mistakes.
I should be able to get a replacement LED locally. It will be interesting to see how much that helps. In the meantime, i have also found that I have an old helmet lamp LED array with 12 white LEDs. I found that if i attached its wires to various places on the circuit board, I could get the whole twelve ( and the orginal two green and one white) white LEDs to flash with the 9 volt battery. My experience with bicycle LED sets is that multiple array flashing LEDs last a very long tome on one battery. I even found this arrangement would work with some old flat 9v batteries. So I reckon that is how I will configure my kit. It might look a bit unconventional, but i don't really care; as I can see it will make a good bicycle flashing front light. Very easy to see, but not blinding. So I will also probably put the kit in some unconventional home-made container. I have used an old silicon sealant tube in the past, with a moisturising cream pot as a diffuser. ;-)