Touch circuit sound, led. 555 timer

[eTech]

Perfectly fine. For testing i can change the pot. Ive got a 501 500ohm

Ok...lets leave as is for now but make note of the timeout setting. What is the timeout currently set to?

 

[ThomsCircuit]

Ok...but:

1.6M+1M=2.6M

I dont follow. I only have the 1M Vr

 

[ThomsCircuit]

Ok...lets leave as is for now but make note of the timeout setting. What is the timeout currently set to?

Dialed all the way down to 6.45min

 

[eTech]

I dont follow. I only have the 1M Vr

Yes...but the 1M VR is in series with 1.6 M R6, so...1M+1.6M=2.6M. Meaning the max resistance for timeout calculation is 2.6M.

 

[ThomsCircuit]

Much of the accuracy depends on the quality of the timing cap

Well these are either from an off planet reseller on eBay or recycled from Chernobyl

 

[ThomsCircuit]

Yes...but

Oh. I had my thoughts messed up. I get it.

 

[eTech]

Well these are either from an off planet reseller on eBay or recycled from Chernobyl

LOL

 

[eTech]

Oh. I had my thoughts messed up. I get it.

No....you didn't.

My bad....

I'm not using R6. Just the 1 meg pot to keep the timeout short.

You can set the time to whatever your comfortable with, just keep in mind what is is and let me know what its set to for testing purposes.

 

[ThomsCircuit]

I'm not using R6. Just the 1 meg pot to keep the timeout short.

I'll remove the 1.6m resistor. Give me a bit to get it to around 10 seconds

 

[ThomsCircuit]

Give me a bit to get it to around 10 seconds

I'm at 16 seconds. Good?

 

[eTech]

I'm at 16 seconds. Good?

That's fine. We leave it set at 16 seconds for the remainder of testing..

 

[eTech]

OK...so repeating the test in post #93, using 16 second timeout, can you post results please?

 

[ThomsCircuit]

repeating the test in post #93

Timer range 16.75 - 17.10 seconds
When clicked
red light goes out
Green & orange come on
Relay engaged
Timer expires
Orange light goes out
Green light stays on
Relay remains engaged

I press manually to disengage relay and return leds to normal state. Repeat test.
I did this test 6 times. Behaviour same each time. ALSO No beep from buzzer upon timer expire

 

[eTech]

Timer range 16.75 - 17.10 seconds
When clicked
red light goes out
Green & orange come on
Relay engaged
Timer expires
Orange light goes out
Green light stays on
Relay remains engaged

I press manually to disengage relay and return leds to normal state. Repeat test.
I did this test 6 times. Behaviour same each time. ALSO No beep from buzzer upon timer expire

When the timer times out, a short pulse is generated at the junction of collector Q1 and R10. The pulse resets the 4013(toggle). This also deenergizes the relay and turns off the Grn LED.

Monitor the voltage at 4013, P10, and see if you can see the voltage change from low to high. It will be a very short pulse, your meter might not register the change.

So...
Repeat test post #93 while monitoring 4013, P10. At the moment the time expires, you should see a "low" to "high" pulse at 4013,P10.

report back.

 

[ThomsCircuit]

Monitor the voltage at 4013, P10, and see if you can see the voltage change from low to high

I do not detect the change on my meter. Here is the connection Q1 and surrounding components. It looks correct. The pin on the far right of Q1 is documented as the emitter. Am I correct?

 

[ThomsCircuit]

I've tried monitoring other components that do successfully go from hi to low (the buzzer) and the meter can't see that either

 

[ThomsCircuit]

I also tried a replaced if Q1 with an identical replacement. No change

 

[eTech]

We need to check/test the Q1 circuit

I do not detect the change on my meter. Here is the connection Q1 and surrounding components. It looks correct. The pin on the far right of Q1 is documented as the emitter. Am I correct?

Looks correct.
Can you verify the cap value? If it has polarity markings, please check.

 

[ThomsCircuit]

Cap x8 has a reading of 505.0nf / .50uf

 

[eTech]

We need to confirm the "auto reset" is working.

Disconnect X8 from U2, P3 so it is isolated from the rest of the circuit. We'll try to test maually by touching the junction of X8/R7 to ground.
That should turn on Q1. 4013,P10 should go from low-to-high, and stay high as long as the junction is at ground.

Monitor the voltage at pin 4013,P10
Try this test and report back.
I'll be gone for about 45 minutes.