Well, this is my first instructable (yay) so, here it goes!
This is a Dark Detector circuit that utilizes 1) the astable ocillator that you can make with a 555 to drive a piezo and 2) the reset threshold of the chip.
Credits to Tony van Roon for the circuit diagram.
For Halloween:
I'm planning to either
1) combine it with a strobe light so with each "off" cycle, it screeches or
2) Put it over the doorbell (so it can be used seasonally too! : ] )
This is a Dark Detector circuit that utilizes 1) the astable ocillator that you can make with a 555 to drive a piezo and 2) the reset threshold of the chip.
Credits to Tony van Roon for the circuit diagram.
For Halloween:
I'm planning to either
1) combine it with a strobe light so with each "off" cycle, it screeches or
2) Put it over the doorbell (so it can be used seasonally too! : ] )
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Signing UpStep 1: Step One: Gather the Parts
_Parts_
555 Timer IC (I used a Texas Instruments NE555P, you can use pretty much any other brand)
A breadboard (doesn't have to be big)
Some wire; bare or stripped (you can use staples if they are thin enough)
One 1 megaohm resistor
One 100K resistor
One 100 ohm resistor (a 100 ohm potentiometer is better but optional)
One 1000 picofarad capacitor (in nanofarads: 1 nF in microfarads: .001 uF)
A Cds cell
A Piezo siren/buzzer
_Notes_
The resistor values can be experimented with but I reccomend these values for the most sucess.
The piezo can also be a speaker.
The capacitor value should probably stay the same.
You can try different Cds cells.
A great place to find components is the Electronic Goldmine: http://www.goldmine-elec.com
555 Timer IC (I used a Texas Instruments NE555P, you can use pretty much any other brand)
A breadboard (doesn't have to be big)
Some wire; bare or stripped (you can use staples if they are thin enough)
One 1 megaohm resistor
One 100K resistor
One 100 ohm resistor (a 100 ohm potentiometer is better but optional)
One 1000 picofarad capacitor (in nanofarads: 1 nF in microfarads: .001 uF)
A Cds cell
A Piezo siren/buzzer
_Notes_
The resistor values can be experimented with but I reccomend these values for the most sucess.
The piezo can also be a speaker.
The capacitor value should probably stay the same.
You can try different Cds cells.
A great place to find components is the Electronic Goldmine: http://www.goldmine-elec.com
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what i have to do
1:pin 1 ground.
2:pin 2 connected with capacitor which is grounded also it also short with pin 6 and connected with one end of potentio meter,pin 7 with other end of potentio meter
3:one leg of ldr connected with ground and othr goes in pin 4 which is reset
pin 3 is output pin.
but matter is i cant understand the function of reset pin,please explain me in digital\logic lang.
Et omnis as in "the page should cover all problems" which unfortunately, it doesn't, as evidenced by many of the comments.
Gotta get those latin phrases down!
So, when the capacitor value is increased and the buzzer is replaced with an led and the light threshold of the circuit is reached, the led would ocsillate at the same frequency that the buzzer would (ie about 100 - 5000 Hz)
Though I'm not entirely sure, I am fairly certain that above is what would happen.
Hoped that answered your question!
what's the output of your schematic?
could it drive a BLUE led? with a smaller voltage supply?
The output of the circuit is pretty much the same voltage that you pump into it. Generally, blue leds can be run at about 4.5 volts DC.
The 555 has a voltage range of 4.5 volts to 15 volts, more than enough to drive a blue led.
Hope that answered your question!
Atleast mention him in the instructable!