Need help with home brew project

[Roff]

No, counting isn't necessary. The brushing of the poly speaker will be a constant,It will always be the same. but being able to adjust the time between when the brushing starts and the 555 fires is a must. For example, During "Set Up" I can adjust the time it takes when I start the brushing of the speaker and when the 555 fires, and change it if necessary. Maybe giving between 1-15 minutes between when the brushing starts and the timer fires.

You didn't answer this question from my previous post:

What is the maximum and minimum time between successive touches?

The answer is important.
Another question: What might be the minimum and maximum number tof touches required for triggering, i.e., you want it adjustable, but over what range?

 

[Roff]

Hee, hee.
I am a dirty old fondler!

We always suspected that.

 

[G_Man]

Once the brushing starts, it will continue at a constant, it would be milliseconds between brushes. Imagine brushing your finger back and forth on the speaker. Maybe 500 brushes to start, like one minute, going up from there to 15 minutes before the timer fires.

 

[audioguru]

I am an audio guy but I have never fondled a speaker.
Most girls can't speak anymore after being fondled 500 times in one minute.
I got slapped once.

 

[G_Man]

Aww, c'mon we all know you have fondled at least one speaker.

 

[audioguru]

Aww, c'mon we all know you have fondled at least one speaker.

Is her moaning almost the same as speaking??

 

[G_Man]

One more thing that might clarify things, I don't want any stray brushing to do anything only trigger the timer when it's sustained for a few minutes, hence charging the cap idea.
George

 

[Roff]

One more thing that might clarify things, I don't want any stray brushing to do anything only trigger the timer when it's sustained for a few minutes, hence charging the cap idea.
George

Capacitor leakage time constants pretty much preclude your cap charging idea. I have hacked out a circuit that basically keeps a cap charged to a fixed voltage so long as the brushing is continuous, and that voltage trips a comparator. The output of the comparator starts an oscillator which clocks a counter, and it simultaneously removes the reset from the counter. If the brushing stops before the counter times out, the comparator detects that condition, turning off the oscillator and resetting the counter.
If the counter does time out (time adjustable 1-15 minutes), it stops the clock but does not reset itself, effectively latching the counter output until the brushing stops. You can take the counter output and trigger a timer, or whatever. It might not work with your speaker without some tweaking, because I don't know what the actual signal out of it looks like.

 

[G_Man]

I thinkI might have most if not all of that sitting on my desk right now. Will a CD4017BCN work for the counter? I also have a LM339 quad comparator.

That sounds like it'll work.

 

[Roff]

I thinkI might have most if not all of that sitting on my desk right now. Will a CD4017BCN work for the counter? I also have a LM339 quad comparator.

I'll post the schematic tomorrow. I used a CD4040 as the counter. With some modifications to the circuit, you could use CD4020 or CD4060 instead. CD4017 does not count high enough to be useful in this application. I used LM393 for the comparator, but you can use an LM339.
You also need a CMOS 555 and an op amp such as TL071 or TL072, and a handful of resistors, capacitors, diodes, etc.

 

[G_Man]

Thank you, Thank you, Thank you!

 

[Roff]

Do you know what you'll be using for your power supply?
I'm going to bed.

 

[G_Man]

9 volt battery.

Me too, late here as well.

 

[Roff]

Here it is. There may be a better way to do this (like with a microcontroller), but I'm guessing you don't want to go that way, and even if you do, I ani't gonna program it for you!
Like I said, I'm just guessing about the speaker signal properties. I ran some simulations, based on a few milllivolts due to background noise, and a few tens to hundreds of millivolts of "brushing" signal, and it seemed to work, but the lowest signal frequency I considered was 100Hz, so you may have to C1 and/or C3 larger. Or it might not work at all. You get what you pay for.

 

[G_Man]

Thanks Roff, I'm gonna give that a try. I have to order a CD4040, don't have one of those. In the meantime I thought of this. I've been playing with it but no luck as of yet. Speaker driving a darlington array driving a small LED so you can see each light tap on the LED.

 

[Roff]

Thanks Roff, I'm gonna give that a try. I have to order a CD4040, don't have one of those. In the meantime I thought of this. I've been playing with it but no luck as of yet. Speaker driving a darlington array driving a small LED so you can see each light tap on the LED.

You said

Once the brushing starts, it will continue at a constant, it would be milliseconds between brushes. Imagine brushing your finger back and forth on the speaker. Maybe 500 brushes to start, like one minute, going up from there to 15 minutes before the timer fires.

OK, I didn't calculate the time based on 500/1min. That's over 100ms per brush. True, it is still milliseconds, but I was thinking maybe 10 or 20 at the most. You may have to increase C3 to 100uF.
Your LED idea is a phenomenon known by engineers as "feature creep" (or creature feep). The marketing guys say, "Hey, those engineers really can make it do all the stuff we wanted. Heck, I'll bet they could add a swizzle binder and a twinkling light!".

 

[G_Man]

LOL, Being a software engineer, I know all about "feature creep".
Seriously tho, not in addition to but instead of, until I receive some parts.

Is this possible? I've been goofing around with a darlington-tip120, trying to get a led to light with each tap.

 

[Roff]

I think software is even more prone to feature creep than hardware.
You won't get enough voltage from the speaker to drive the Darlington unless you bias it into class A operation. I think you can use one of the left-over comparators in the main circuit, once you get it built.

 

[G_Man]

Can you give me a general circuit breakdown for this? I have a comparator sitting here along with a tip120.

Already ordered the counter from newark.

 

[audioguru]

Like I said on the other website, my "fondling" (hee, hee) of a speaker made a low voltage as seen on my 'scope.
It is a 5" 4 ohm speaker.
1) Rubbing it pretty hard produced a peak voltage of 0.1V.
2) Hitting it pretty hard produced a peak voltage of 1.0V.

Not enough to turn on a darlington transistor.