There is no schematic.Thanks for the replies, I have tried replacing the relay with an led and I have tried replacing the 555 timer itself but it still did not work. When I checked the voltages on pins 6 and 7 as suggested I found that the capacitor was not discharging. Any suggestions would be appreciated.
Edit: here is a drawing of my circuit
Are you using 9V or 18V? It seems that you wanted to use 9V, evaluating the LED resistor, but you have 18V depicted there. I think you meant +9V and 0V (or GND).
Your circuit seems to be OK, so if you are having misbehaviour, check the connections that you are making. Check for bad joints.
Your circuit should have the LED on for 0.76s and off for 0.69s, so you should see the LED blinking if you follow your schematic. Formulas are:
Ton = ln (2) x (R1 + R2) x C (charge will be done through R1 and R2)
Toff = ln (2) x (R2) x C (discharge will be done through R2)
Also, check if you have a protection diode in parallel with the relay coil. This diode should be reversed. If your relay doesn't have a protection diode built in, you might need this external relay. Without this diode, the 555 timer will be triggered by the back emf generated by the coil, thus behaving erratically. I know this because I happened to have this diode disconnected in a similar circuit. Eventually, you may damage the 555 timer (the LMC555, since it is a CMOS IC, would be damaged pronto).The schm works. I've tested it with the said RC values and Ton(fosc)=0.79s(approx)
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