no meriam tam nulu
Steps to follow if the shift light doesn't work when you construct it:
1. With the engine running check the input to the circuit (rev counter input) for a pulse. An oscilloscope is ideal, otherwise check that the input has an AC component to it, which should rise with increasing revs.
2. With the circuit powered up check that you get 7.5V at pins 8 & 9 - this is set from the internal zenier diode in the LM2917.
3. With everything connected together check for a voltage on pins 5 and 10. This should rise as the revs increase. If it does not then you will need to adjust the capacitor on the input to pin 1. I used a prototype board to try out many different capacitor/resistor combinations, and picked the ones that gave the lease ripple on the output from the LM2917.
4. Check the voltage fed into the op-amp from the variable resistors. When the output from pin 5 gets above the output from the variable resistor the light should go on.
5. If everything checks out so far then you need to check the polarity of the LEDs. For testing I used two LEDs wired in opposite polarity so one would light even if I connected them to the circuit backwards.
6. Have you connected the LEDs to ground, not +12V?
robil som to podla tohto.. tak teraz ked tam nemaram to napetie tak co by som mal skusit pozriet?