4017 as a variable resistor??

[k7elp60]

This is a circuit that may do what MR. Deb wants.
1/2 of the 556 operates as a one-shot when triggered by a negative trigger from the PIR. The one-shot is high for about 11 seconds and turns on the other half of the 556 which is a astable with a high period of 2 seconds and a low period of 2 seconds. On PIEZO is on when the astable is high and the other one is on when the astable is low.

 

[MrDEB]

Deer sound hearing abilities

As I read some info Deer hear 2khz to 6khz
I figure (hope) that cycling between the two frequencies (2khz, 3khz,4khz,5khz,6khz) then 5khz,4khz,3khz) would drive them deer away by being annoyed. by the sound.
have seen numerious circuits that use an 8ohm speaker unless there is a better solution??
I may have to breadboard one and try it out??

 

[audioguru]

The better solution is to use the 556 oscillators as oscillators and use a power amplifier to drive the speaker.
You don't need two speakers. A single speaker can produce thousands of sounds at the same time.

Calculate that the output high voltage of a 556 is about 7V when it has its max allowed output current of 200mA and a 9V supply.
But 7V across an 8 ohm speaker is a current of 875mA and the 556 will smoke then die.

 

[MrDEB]

any suggestions on amp?

maybe an op amp but ???

 

[blueroomelectronics]

When your Junebug arrives you'll probably want a simple amplifier that can be driven by a square wave or simple integrator. I've been looking for such a design myself (LM358?)

 

[MrDEB]

how about an lm386?

looking through my Forest Mims circuit book for simple amp.
looking at an LM386
has a fixed gain of 20 but can be increased to 200
them deer don't stand a chance---lol

 

[MrDEB]

just need a weather resistance

speaker or ??
are mylar speakers for out-door usage??

 

[Roff]

If this thing goes off at night (when deer feed), neighbors may be more annoyed than the deer. Unless, of course, there are no neighbors.

 

[audioguru]

An LM386 has a whopping power output of only 450mW into 8 ohms at clipping with a 9V supply.
Like a cheap clock radio.

 

[colin55]

Do you want a wailing siren circuit that goes from 2kHz to 7kHz and back again?

 

[be80be]

looking through my Forest Mims circuit book for simple amp.
looking at an LM386
has a fixed gain of 20 but can be increased to 200
them deer don't stand a chance---lol

You have love him he wrote some real good books I have all of his min note books use your lm386 your not wanting to play mp3 just make noise. or try it like this

 

[MrDEB]

may fry the 555

audioguru recommends against driving an 8 ohm speaker off the 555. draws too much current (see his post about 4 before this one)

 

[be80be]

One uses Dc decoupling and one is driving by a transistor They both work with a 555. the capacitor is charging and diving the speaker on the one on the right. and a transistor is driving the one on the left. So his thinking does not apply. he saying you can't drive it from the chip it self which is right. these to circuits are not driving by the 555 it self.

 

[be80be]

(see his post about 4 before this one)

I read all the postings

 

[audioguru]

Forrest Mimms shows the 555 driving the 8 ohm speaker with a 51 ohm current-limiting resistor and a coupling capacitor.
Then the current in the speaker is only (9V - 2V)/2 divided by 8 ohms + 51 ohms = 59.3mA. The total power is 59.3mA squared x 59 ohms= 0.2W for the square-wave. The power in the speaker is only 28mW (like a loud earphone).

 

[be80be]

I didn't say it would be loud but it works if he wants loud he has to use a amp. But deer can hear you walking in the grass at 50 to 100 yards. I don't think you'll need it to loud. Maybe he wants to run them out of town.

 

[MrDEB]

just to the local forest

deer season come fall.
got my first deer last season (the DFG had a special doe only season)
mighty good eats. no gamey flavor associated with a buck.

 

[MrDEB]

as for adjustable resistors/4017

downloaded Multisim and started playing around. not sure how accurate but got a 555 with variable frequency output.
the screen shot is just to see if my idea will work.
planed to control the resistors/transistor section with a 4017
use a 555 for the timer for incrementing the 4017 . A 556 for generating the 2 seperate frequencies with the 4017 driving the 2n2222(2 per output) A 556 has the timing resistors in parallel to output the 2 seperate frequencies to chase them deer away hopefully.
the N.O. mont switches are just to see if it would work
basically the 2n2222 put a resistor in parallel with the timing resistor on the 555/556
need to calculate the values for frequency output.

 

[audioguru]

You have the duty-cycle of the 555 so that the capacitor charges (which makes the output high) for 500 times as long as when the capacitor discharges (which makes the output low).
For a duty-cycle that is close to 50:50 then the upper resistor needs to be the low value and the lower resistor needs to be the high value. But then changing the value of the upper resistor will barely change the frequency.

Look at the datasheet of the LM555. The "pulse position modulator" shows that changing the voltage at pin 5 changes the frequency a lot. The duty-cycle changes a little. A resistor to ground will make the frequency the highest then add a resistor to a positive voltage with the CD4017 driving a transistor to make the frequency lower.

 

[colin55]

Do you want a wailing siren circuit that goes from 2kHz to 7kHz and back again?