Touch circuit sound, led. 555 timer

[eTech]

Notice that the BC327 has pin out reversed from most - reading with the flat side to you and pins down -
Collector, Base, Emitter.

The BC327 on my bench circuit is good.
I tried reversing the leads on my bench circuit as a test, but it didn't match the behavior the TS was seeing.

 

[ThomsCircuit]

Fairchild.
BC32740

 

[ThomsCircuit]

I'm using a BC327-40. but a 2n3906 or 2N4403 will work also.

I do have 2n3906. I did try it with all schematic configurations restored. Same result. Tried it with x8 disabled and the lead that went to pin3 of the 555 to ground. Voltage remained low while the lead was inserted to ground or removed.
I documented the voltage readings of the 555 in idle, ontimer, and expired timer.
1) 0.0 - 0.0 - 0.0
2) 5.2 - 5.2 - 5.2
3) 0.0 - 4.7 - 0.0
4) 0.0 - 4.7 - 4.7
5) 3.4 - 3.4 - 3.4
6) 0.0 - 2.5* - 0.0
7) 0.0 - 2.5* - 0.0
8) 5.2 - 5.2 - 5.2
* steadily climbed passed 3.0

 

[eTech]

I do have 2n3906. I did try it with all schematic configurations restored. Same result. Tried it with x8 disabled and the lead that went to pin3 of the 555 to ground. Voltage remained low while the lead was inserted to ground or removed.
I documented the voltage readings of the 555 in idle, ontimer, and expired timer.
1) 0.0 - 0.0 - 0.0
2) 5.2 - 5.2 - 5.2
3) 0.0 - 4.7 - 0.0
4) 0.0 - 4.7 - 4.7
5) 3.4 - 3.4 - 3.4
6) 0.0 - 2.5* - 0.0
7) 0.0 - 2.5* - 0.0
8) 5.2 - 5.2 - 5.2
* steadily climbed passed 3.0

Huh? Pin 3 is the 555 output. Connecting pin 3 to ground will short circuit the 555 output.
That is why I asked to disconnect the lead of X8 or just remove X8 from the breadboard for this test.

If you need to back track, just restore the circuit as shown in the schematic, remove cap X8, then connect a ground to the junction of R7,D13,R9. That's it.

Current will then flow from the base of Q1 thru R9, then to ground thru the test ground connection. That turns Q1 on and applies 5v to Pin 10 of the 4013. Pin 10 will stay at 5v until the ground is disconnected.

 

[ThomsCircuit]

Connecting pin 3 to ground will short circuit the 555 output.

Your up late. Here's 2 quick pics. Before and after

 

[ThomsCircuit]

I did remove x8. And that blue lead changes to brown then goes to ground.

 

[ThomsCircuit]

I even relocated that part of the circuit to a different location and changed all the components. I was so hopeful it would work. But pin 1 will not go high.

 

[ThomsCircuit]

The 327 is connected as follows
Collector to pin 10 of the 4013 & to ground via a 10k resistor
Base goes to 5v via a junction of 3 resistors and 1 diode.
Emitter goes directly to 5v
On the other side of the junction is a lead that goes to ground.
The result from this test is the collector remains low.

 

[eTech]

Hi

Here is a photo of my working circuit. This uses a 2N3906.
It is shown with the orange test jumper connected to ground. The measuremet at the test point is 5v
When this jumper is disconnected, the voltage measured at the test point changes to 0v.

 

[ThomsCircuit]

I began just setting up an isolated circuit to just test the transistor. Im going to hook mine up like you have and try this.

 

[ThomsCircuit]

Here is a photo of my working circuit.

Somtimes a picture is worth 1000 posts.

 

[ThomsCircuit]

Im going to hook mine up like you have and try this.

Well well. That worked.
I've completed the test. While I had it set up I tested all 327 transistors.
The breadboard is now reconfigured with the correct layout. The 16 second timer test works. I think, if you agree, we can now increase the buzzer duration to .5 - .75 seconds. I think this photo shows the buzzer portion.

 

[ThomsCircuit]

Here is a photo

I do want to thank you for the detailed photo. I did take the time and try to understand why my interpretation of that portion of the schematic was so wrong.

 

[eTech]

Well well. That worked.
I've completed the test. While I had it set up I tested all 327 transistors.

Cool..
.

The breadboard is now reconfigured with the correct layout. The 16 second timer test works. I think, if you agree, we can now increase the buzzer duration to .5 - .75 seconds. I think this photo shows the buzzer portion.

Ok..lets move on to the buzzer.

 

[eTech]

We can adjust the buzzer duration by change the RC constant of both X10/R16 and X9/R19.
This will be manual tuning sort of thing.
Lets try doubling the current duration by doubling the size of R16 and R19.
So change both R16 and R19 from 330k to 680k.
Then try the circuit while listening to the buzzer.

report back.

 

[eTech]

I do want to thank you for the detailed photo. I did take the time and try to understand why my interpretation of that portion of the schematic was so wrong.

So...the take away from this is that our troubleshooting procedure worked well. We were able to "zoom in" and drill down to where the problem existed because we tested each circuit block one at a time.

You did good.

 

[ThomsCircuit]

change both R16 and R19 from 330k to 680k.
Then try the circuit while listening to the buzzer

Updated to 680k. Tested. Unnoticeable difference.

 

[eTech]

Updated to 680k. Tested. Unnoticeable difference.

OK...leave the 680k resistors in and change each cap (X9,X10) to 10u, 10v min.

report back...

 

[eTech]

OK...leave the 680k resistors in and change each cap (X9,X10) to 10u, 10v min.

report back...

Pay attention to the capacitor polarity markings if any.

The + side of X9 should connect to 4013,P12.
The + side of X10 should connect to 4013,P13.

 

[ThomsCircuit]

change each cap (X9,X10) to 10u, 10v min.

Done. Sounds nice. To adjust it i would increase both R & X?
‐---------------------
This last part is the alt power circuit for touch switches over 8 feet from the circuit. I will take a closer look to be certain its wired correctly. I'll return with my results