and this is what i did..
i replaced the:
-22M ohm with just 1M ohm
-[variable resistor]940k ohm with 500k Ohm [variable resistor]
i scraped R8 using a scissor, just like cutting an ordinary paper [desperate act..LOL!) but of course i did it with care.
before running the circuit, i tested the scraped resistor's behavior with an ohm meter.
My findings:
-when i hold the scraped part, resistor value lessens
-[this is actually disgusting...sorry about this]i licked my finger then touched the scraped part & surprisingly, the reading approaches 0 fast! then slowly goes back to the original value(1m ohm)
-i tried blowing it, nothing happens
running the circuit
-same test above, same results[ohm meter readings while circuit is on]
-but the LED never lit.
-i expect, it should have lit as i gone biasing..[potentio and R8 test]
-as i vary the potentio[500k ohm] the input at pin3 of lm393 varies[as i expected]
-but when i did the test with R8, which is conected to pin2 of lm393, it never affects the input voltage for the said pin. which means, lm393 output at pin1 is just dependent on the potentiometer
--R7 prohibits high signal for the inverter[always low regardless of the opAmp output since they are parallel], causing it to always output a high resulting to an off state LED..
-but when i short pin1 and pin2 of lm393 the LED lits.,
any comment on this?
Thanks a lot!
-carl-