Thanks to God & Thank you so much everyone , I really can't thank you all enough
Les Jones indeed both BC548 & BC337 wiring weren't correct, for that purpose I used several parts of IC sockets to make the components that are likely to fail easily replaceable
I blown the few remaining BC548s & BC337s I had, despite the correct pin out.
I have seen SL100 used in many circuits online, & it's hard to find an equivalent that fits in directly.
I tired to measure the current drawn during charging, the Fast Charging mode the battery draw about 700 mA & the Float Charging mode it draw 300 mA
I used a small 12v 4Ah to test the circuit, but I plan to connect it to a car battery 12v 70Ah & I really have no idea how will it perform
Misterbenn Special thanks to you sir, your advice did the job
I did exactly as you said & it finally worked you saved the last two BC548 & BC337 I had
now when I adjust the POT connected to pin 2 I can safely make the relay (energize - de energize) but I'm afraid that if I let that happen normally during charge, that the relay will behave erratically.
as I have mentioned that I made the voltage monitoring circuit on a separate PCB, I thought to add more functionality to it, so I connected a digital Panel Meter, it has 4 pins, I connected the +5V to the output of IC4 (
(I put a small switch to turn it off when not needed), ground to ground & the 4th pin to the Battery positive terminal, but sometimes when I turn the panel on it causes the relay to behave erratically by that I mean
switching on/off rapidly , switching the panel off/on solves that but I don't know exactly why ?!, could it be the negative terminal connected to Pin 4 of IC1 & Pin 11 of IC5 ?! or small current/voltage fluctuations drawn from IC4 disturbing the reference voltage of IC5 ?!
I do agree the circuit is far from perfect , as I don't have enough knowledge or experience so the circuit seemed pretty convincing to me.
ericgibbs that seemed to be the case before connecting the 10K & 1K resistors , thanks a lot for you efforts simulating the driver circuit
JimB I do agree, I really had no Idea but I have searched about those two opposing Zeners, & found out that they perform full wave clipping
audioguru thanks a lot for the useful information, I will never do it again, although I have learned a lot of interesting stuff while making this charger circuit.
AnalogKid thanks a lot for your interest
gophert that's exactly what I have thought about it before going through all that pain.