Basically when a pendulum swings in a clock it will break the beam of light to the light sensor (photo transistor) when this happens the the 555 will run for a given amount of time sending power through to an external device.For the purpose of the experiment I used and LED. for the external device.This does happen but the 555 does not time out.I want the 555 to time out after about 3 sec's.
When the transistor is receiving the light then the circuit runs ok (no power going through to the external device)
Due to my lack of electronics knowledge I am now at a loss.I have been at this for hours trying to get it to work.
The timining resistor and capacitor should be chosen according to this formula: T = 1.1 R C; for 3 s you can use 68kΩ and 47 uF, for example. As you know, tolerances affect the ideal behaviour.
You didn't placed a current limiting reistor at pin 3.
Have you checked the output with a multimeter, without the LED?
The timining resistor and capacitor should be chosen according to this formula: T = 1.1 R C; for 3 s you can use 68kΩ and 47 uF, for example. As you know, tolerances affect the ideal behaviour.
You didn't placed a current limiting reistor at pin 3.
Have you checked the output with a multimeter, without the LED?
I did as you sugested and put a multimeter inplace if the LED. and when no light going through to the transistor the meter shows the 9v that is flowing through the circuit.
Markelecto, I agree with eng1 you still need a current limiting resistor in series with the LED on pin 3. I have also found that most electrolytic capacitors greater than about 10uF cause timing problems because of the leakage current. A better solution is use a higher value of resister in the timing calculations.
Sheldorstv, your diagram for your circuit should have about a 1K resistor in series with the 1M pot if the pot is adjusted near 0 ohms the current to pin 6 and 7 could exceed maximum value.
Lower the resistor, brigther the LED. Did you a use 560 ohm resistor? I expect the LED current to be about 10 mA with a 560 ohm resistor. That's reasonably enough?
Cheers eng1 for that.I got my resistor values mixed up.
You will now see the led. glowing like a light house.thanks to hm:
Cheers audioguru for the new schema!!! I added mine a logic level just so you all could see the flow.I am now very happy to see it up and running corectly.I THINK!!!