Hello.
I just wanted to give a brief introduction of the type and purpose of my circuit.
The circuit is designed to turn on (go high) for a time determined by 0.693R1C1 and do this (go low) periodically after a time determined by 0.693R2C2.
I got this operational by using two diodes D1 and D2 on the to block the current for the normal operation of the the low state which was determined by 0.693(R1+R2)C2.
I got the circuit to function but the time I computed from the equation is about 40% off in both high and low states. The high time varies between 1013 seconds and low is between 4mins 20seconds to 4mins 40 seconds.
This is my first time operating on such a circuit so I'm not to sure where to look to troubleshoot it. So far I've guessed that it was a faulty IC but this is about the 4th circuit that I've done with basically identical values. I've measured the capacitances of my capacitor and determined that those are not the fault. Any idea of what could be going wrong?
I have enclosed a circuit diagram of my circuit:
I just wanted to give a brief introduction of the type and purpose of my circuit.
The circuit is designed to turn on (go high) for a time determined by 0.693R1C1 and do this (go low) periodically after a time determined by 0.693R2C2.
I got this operational by using two diodes D1 and D2 on the to block the current for the normal operation of the the low state which was determined by 0.693(R1+R2)C2.
I got the circuit to function but the time I computed from the equation is about 40% off in both high and low states. The high time varies between 1013 seconds and low is between 4mins 20seconds to 4mins 40 seconds.
This is my first time operating on such a circuit so I'm not to sure where to look to troubleshoot it. So far I've guessed that it was a faulty IC but this is about the 4th circuit that I've done with basically identical values. I've measured the capacitances of my capacitor and determined that those are not the fault. Any idea of what could be going wrong?
I have enclosed a circuit diagram of my circuit:
Attachments

34.2 KB Views: 39