Need help with timer project!

[SteveCPerrino]

I'm relatively new to electronics, I've been studying them in my free time for about a year, and I just recently attempted one of my first builds. The schematic, stripboard layout, and parts list are available here:

Adjustable 1-10 Minute Timer Project

I did everything I was supposed to (I think), and the green LED isn't turning on (it doesn't work at all).

Can anyone look at these pictures I took of my circuit and maybe help me see what I did wrong?

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[MikeMl]

Your pictures are too fuzzy to see a miswire. Does the red led/buzzer come on after the delay?

Have you tried reversing the green LED?

 

[ronv]

Timer

Interesting.. Bad circuit.
Remove 33k and .1 ufd.
Move pin 7 to junction of 1 meg and 100k
Tie pin 2 to pin 6 and to junction of 100k and 220 ufd.

 

[MikeMl]

Ron, he is not trying to build a free-running oscillator, he wants only one cycle. The RC network on the TRIG pin is there to trigger the 555 ONCE as power is applied.

 

[SteveCPerrino]

Yeah, I'm sorry, I was worried about the picture quality haha

The red led/buzzer don't come on after the delay, and reversing the green led didn't do anything either.

All the components are in their proper places and I'm pretty sure I wired everything according to the schematic.

 

[ronv]

Oh. I get it. Time for the voltmeter. Strange neither one is on. Sounds like no 9 volts or no ground.

 

[SteveCPerrino]

I figured out something, haha, I realized that the 0.1ufd was misplaced, so now the green LED turns on, but when the green LED turns off, the red LED nor the buzzer turn on. I checked every connection and placement and everything is where it's supposed to be

 

[MikeMl]

The anode of the LED goes to the switched +9V?

The cathode of the LED goes to the red buzzer lead?

The black buzzer lead goes to pin 3 of the 555?

 

[SteveCPerrino]

yep, I checked and I wired all that correctly

 

[SteveCPerrino]

do you think that it's because I have a 12V buzzer? The schematic said that it would be okay, but the fact that there's only 9V in the circuit, would that maybe be the problem?

 

[MikeMl]

Could be. Replace the buzzer with a 470 Ω resistor. If the Red LED lights as expected, you have found your problem.

Try the buzzer directly across a fresh 9V battery.

 

[SteveCPerrino]

I replaced the buzzer with the 470ohm resistor and the same thing happened, I don't know if this information helps, but when the two red LED leads are connected the buzzer goes off.

 

[MikeMl]

Then you have a shorted RED Led. If that is a true buzzer (coil, vibrating points), then the inductive kick that happens as the points open will blow up a Led. I think the circuit designer was thinking of a Solid-state Sonalert, not an electromechanical buzzer.

 

[SteveCPerrino]

ohhhhhh, okay, that makes a lot of sense, thank you so much for all your help