Touch activated Switches

[killivolt]

Can you try it out? It should work, but I wouldn't want to make any predictions.

Thank you Roff Yes, I will.

I would suggest you put some capacitance from the wire to ground on both sides. Maybe about 1000pf or so

Ok, I will. I'll give a report on both.

Thanks to both of you.

Cheers. Report tomorrow. Hopefully, without rabbit trails, caused from work.

 

[Space Varmint]

Thank you Roff Yes, I will.




Ok, I will. I'll give a report on both.

Thanks to both of you.

Cheers. Report tomorrow. Hopefully, without rabbit trails, caused from work.

Is the wire shielded per chance? Some RG-174U would work nicely.

 

[killivolt]

Actually I had some extra 3 conductor mini Microphone Cable. I salvaged it when we moved our rooms over to the new location. It does have some shielding.

If I remember correctly it has a foil covering all the wires. I thought about twisted pair. The previous Fellow that held my position broke the ends off 2 100ft spools of CAT5.

I've been wanting to remove and separate the wire to be re-spooled. When I'm done it won't be of any use for network cable or at least I wouldn't trust it.

 

[Space Varmint]

One thing about shielded cable is, you would need low impedance to send the signal. But then you might have to use a step down transformer and all that. If you ran it through a buffer amp of the emitter follower variety it would give you a low Z out. Actually, that would be the best way to go but let's see what happens first. The circuit may be just fine the way it is. We are getting ahead of ourselves here

 

[Roff]

One thing about shielded cable is, you would need low impedance to send the signal. But then you might have to use a step down transformer and all that. If you ran it through a buffer amp of the emitter follower variety it would give you a low Z out. Actually, that would be the best way to go but let's see what happens first. The circuit may be just fine the way it is. We are getting ahead of ourselves here

You shouldn't need a lower impedance driver, as the capacitance of the cable has been accounted for. Reflections won't be a problem either, since risetimes are slow. This is from the PDF that contains the schematic:

 

[Space Varmint]

Cable? Well I was referring to like coax but I said he had some audio cable. Isn't that about 75 ohms? I see your spec on the length but my concern is with noise. If he used shielded cable that would eliminate any chance of noise getting into the circuit. Now he is using a MOSFET for the line driver, correct? It would tend to have a high impedance output and input and would be a bad match to say some coax cable like RG-174U. It all hinges on rather there is any noise pickup. Even running it through a buffer with a low Z out will reduce noise with open wire. Especially on the receive side.

Hey, but like I said. Let's see what happens first.

 

[killivolt]

Ok, I went over it again tonight and found I based all the connections off the wrong point thinking the 9v supply was doing something it wasn't. I had to redo everything practically.

One last check with the "DMM" then I'll power it up.

 

[killivolt]

Got it.

Now, I put the DMM on it and couldn't see 20khz ? Does it have to be in series ?

Edit: maybe not I got a waveform but I had to turn it way down on the voltage to see it.

 

[Roff]

Where were you probing?

 

[killivolt]

Where were you probing?

Exciter out.

I set it on .1 volt/Dev and 20us Time/Dev and then if I put the bottom of the signal on the center Horizontal line then I get a total of 10 hash marks vertical sign looking similar as the one above the exciter in the diagram.

But if.

Go to the left rail after the 10k.

I set it at 10 Volts/Dev and 20us Time/Dev not quite 3 hash marks vertical with a sign wave that is an exact replica of the one depicted but not the square ones you see above next to the oscillator.

 

[Roff]

Ground to Exciter out.

Try probing at the output of the oscillator. I tried simulating the output stage, but I don't have a spice model of the CD4069. I tried making one from MOSFETs, and I also tried 74CH04 (at 5 volts instead of 9V), and the results were flaky, to put it mildly. Still, it could actually work fine in hardware.

 

[killivolt]

On the left rail after the 10k.

I set it at 10 Volts/Dev and 20us Time/Dev not quite 3 hash marks vertical with a sign wave that is an exact replica of the one depicted above the exciter not the one above and to the right of the Oscillator.

 

[killivolt]

Should I be getting 9v to 0v like the Depiction of the diagram above the Exciter output?

I only have 5.47v on my Dmm to ground at tbe Oscillator and 0.775v on the Exciter output.

Edit: I guess I'll just build the rest of the circuit and try it out.

 

[Roff]

On the left rail after the 10k.

I set it at 10 Volts/Dev and 20us Time/Dev not quite 3 hash marks vertical with a sign wave that is an exact replica of the one depicted above the exciter not the one above and to the right of the Oscillator.

I have no idea what this means. Hash marks? And does your DMM show waveforms? What kind of DMM do you have?

 

[killivolt]

On my scope I have 6 vertical square's inside them are smaller dividing lines which inside each vertical or Horizontal square I counted 5.

I'm calling the smaller dividing line's hash marks. I didn't know how to refer to them.

Edit: The Dmm does not show waveforms.

Edit:Edit: I'm going back into the shop today to try and finish. I just got off a website that shows how to accurately set the ground reference.

When I was able to capture the signal I just laid the bottom of it on the center Horizontal line and recorded the peak vertical with those settings on the scope.

 

[Roff]

I didn't know you had an oscilloscope. What kind is it?
You need to learn how to interpret what you see. Do you have a manual? You should be able to get voltage and frequency from the screen.
If you don't have a manual, Google things like oscilloscope basics and oscilloscope tutorial.

 

[killivolt]

I didn't know we moved another page. Anyway yes, I just got off a website about that and I'll have to do some more measurements using the lessons in the tutorials.

I'm just concerned that I didn't get a square wave at the oscillator output after the 10k resistor.

Edit: I just came back after looking at your profile. I like to fish too, when I can get away from work. But, that's been 2 yrs.

 

[Roff]

You should have a square wave on the left end of the 10k resistor, not on the right end.

 

[killivolt]

You should have a square wave on the left end of the 10k resistor, not on the right end.

Ok, I'm going to eat and head back to the shop. I think it's working but I really don't think I have a high enough voltage.

 

[killivolt]

I don't have a square on the bottom. It slopes up slightly. I'm wondering how clean my power supply is now?

Edit: I had some serious issue's after pulling everything up again. Would you even believe I never Vcc'd the second 4069.

my wife calls me last night and I had to hurry out. When I came back, you guess it. Hopefully I didn't do any damage.