THANKYOU SPARKFUN FOR THE TWENTY BUCKS!
THANKYOU HACKHUT FOR THE FOURTY 555 TIMERS!!
I'M DRUNK ON TIMERS!!!
Welcome 555 Timer enthusiasts!
I came up with this circuit while designing a workshop series at 3rd Ward last fall. I had already run a class called 'Electro-Lab, Robotics Edition' where we learned analog electronics and built a simple robot that is attracted to light and avoids obstacles (Machina Speculatrix). I wanted to try something new and since Halloween was coming up, I figured "Hey, wouldn't it be great if I could come up with a cool 555 Timer circuit for Halloween...". Here it is.
Haunted House Bones is a spooky, multi-media Halloween party kit. Build this circuit to get the basics, and by then you'll be so damn good at working with 555s you'll have 30 more ideas for tricky treats. I'll explain what's going on and how it works after the video.
Step 1: Spooky Sounds ~555 Timer~
I wanted to make that classic B-movie ghost sound, a kind of warbling low "Oooooohhh" often heard on the Scooby-Doo. There are three oscillations that make up the sound. First there is the Wailing Zombie tone itself, then there's the Chilling Vibrato, and then the Creepy Warble. Making an evil tone is easy with the 555 in A-Stable, as most of you already know, but I had to somehow add two more overtones on top of the Wailing Zombie... I dug around '555 sirens' circuits online and tuned one to get the Creepy Warble part of the circuit. It's based on tweaking numerous examples. Since the Creepy Warble sound came from driving the Control Voltage (pin 11) of my Wailing Zombie oscillator, I played around with those for a while, to no avail. After scratching the old noggin, I built the Chilling Vibrato oscillator, and simply tied various parts of it to various parts of the Wailing Zombie tone generator. Trial and error lead me to discover the great effect of connecting the two Trigger/Threshold's together with a large resistor (smaller that 100K won't work as well. Go ahead, try it). I haven't probed it with a scope (yet), so I don't know what the hell is happening, but hot damn! It Works!
I have a 10K trim-pot to adjust the tone of the Wailing Zombie tone generator. You can dial in a tone that sounds like a Spooky Ghost or a Screaming Banshee or any freaking creepy thing in-between. I know you're a smarty-pants and you are thinking, "Hey, I bet if I replace the Wailing Zombie trim-pot with some other 555 output, It could get even MORE creepy!". That, my friends, is the true path to drooling insomnia.
*** An important note. In my diagrams, the connections have black dots. If there is no black dot, there is no connection. Just keep banging away at it, it will start to oscillate soon :)
Step 2: The 'Trick' Part. ~one Shot~
"All I need now is an infrared trip-wire and some evil eye LEDs."
I built the IR trip-wire off of an LM386 rigged as a comparator. The IR transistor (EL-PT204-6B , the IR emitter is EL-IR204-A )is connected to the inverting input of the Op Amp, along with a pullup resistor. I also have a trimmer connected to the non-inverting input for tuning. The output of the Op Amp is connected to a 555 Trigger. When the circuit is tuned correctly, here's what happens: If the IR beam is interrupted, the inverting input sees a voltage more positive than what the (tuned) trimmer is supplying to the non-inverting input and so the output is driven to GND. That pulls the Trigger pin on the 555 timer down well past 1/3V (here's my one-shot), and the 555 asserts its output (drives it to +V). The output of this Mono-Stable 555 is connected to the Reset pin of the Wailing Zombie circuit.
In a dimly lit room, I was able to achieve a usable IR trip-wire range of about 3 feet. not bad for doorways, hallways, sidewalks.....
*****I will not be liable for any damage to property, real or imagined. Nor by publishing this documented how-to am I an any way recommending that the above and/or below be used bult destroyed hidden given away for or toward any purpose plot or party whatsoever. < :D
In this configuration the One-Shot only controls the Wailing Zombie, while the Chilling Vibrato and the Creepy Warble circuits are free-running. An improvement would be to switch all the Reset pins with the IR trip-wire (?). That would reduce the current consumption, but I'm not sure how it would effect the spookiness of the sound.
Step 3: Evil Eyes ~555 Timer~
Here are some more oscillators.Who can resist? It's Halloween for Hell's sake.
The Spooky Blinking Eyes is a classic. Rigged up with a short 'off' time and long 'on' time to simulate an unnerving blinking stare.
The Spooky Fading Eyes uses an RC relaxation oscillator to fade on and off a pair of googlies. I'm getting nightmares already!
Play around with the R's and C's on these circuits and see if you like it better.
Step 4: Go on Now, Haunt Your House.
By now you're already thinking about strobe lights, bottle rockets, and ceiling fans. Or hell why not strobe the whole damn house? If you want to interface with high voltage AC, you're on your own, but let me recommend the Sharp S216S02 Sold State Relay. Here's some features:
~ Minimal current. Unlike magnetic relays, these use an internal LED to make the magic happen. Use a high value series resistor with the + or - pins!
~ Zero Crossing. That means when it turns on, the High Voltage side of the circuit waits until the AC wave crosses 0V. No joke. I don't know how it works either. Something to do with a Triac and/or a Diac or maybe a Dalek. Doesn't matter. This will not work on any DC circuits! RTMFDS!
Have fun! And if you can't be safe, be careful.