I am looking for a simple tilt sensor circuit that will sound an alarm and that will run off a 9V battery? If anyone could point me to some designs or a predesign circuit I could buy; I would be most greatful.
Thank you for your time.
A mercury switch can do that:
HTH Wolfgang
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Sorry... but that wont work... It can't self set. I am looking to build a tilt alarm... one that can be set anywhere at any angle and will go off when moved... A mercury switch can not self level and set at any angle... where a tilt sensors can be used in a circuit to read and remember the angle and be design to set-off an alarm when moved. This is the circuit I am seeking.
Maybe you want a vibration alarm? A mercury switch that can be rotated?
You could use an (1, 2 or 3-axis) accelerometer to measure gravity, but that would be expensive and might consume too much power for batteries even if it was pulsed.
Best regards, Spehro Pefhany
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Spehro Pefhany wrote in news: snipped-for-privacy@4ax.com:
The simplest way I know is a vibration switch, like you said, with an SCR in series with the alarm, and the switch to trigger it. To untrigger it, you have to momentarily disconnect the supply.
Maplin used to sell a small switch in the UK, and I still have one around, it is sensitive to small hand movements but insenstive to orientation so long as it's still. I can't remember the part code though, and I don't think they sell them now.
It will NOT detect tilt, if applied very slowly, but is that really what you want? If it is, then you'll have to use three, one in each axis, sum their switched voltages, then detect the change in the summed output to trigger the alarm.
To make things clear I will not use mercury switchs!!!
I could though use a two axis accelermeter.... I am looking at Memsic 2125 Dual-Axis Accelerometer. With Low current operation: less than 4 mA at 5 vdc... it has Simple, pulse output of g-force for X and Y axis but am have trouble locating what the X Y output is when moved.
Sorry, got confused to who I was answering.. first bit, to the poster I answered, last bit, to the first poster. Also, meant three mercury tilt switches (not vibration type).
Also, how much tilt do you want? if it's less than about 45° from horizontal, and if you want proportional sensing not switching, then maybe a tiny joystick, mounted upside down, with a small weight on the toggle? You'll have to experiment with the mass, and the length of toggle extension, but it's cheap, and might be accurate. You can use op-amp based comparison to a preset voltage made equal by reading the current value at will, copying it to a sample and hold (LF412's are good for all these tasks), and if the thing is moved, the voltage change can be detected. Adjust sensitivity by gain (in the sensor amp) and hysteresis (in the comparator stage). You could do this for both axes but you might get good results from summing them and watching the combined output if it's not important exactly what degree of movement occured in which axis.
Forget my sample/hold, got a simpler idea. Charge a big capacitance. :) That way slow changes won't set the alrm off, but fast ones will, and it won't droop over time, and you get better control of what respose speeds you want. The current value can be passed to the capacitor via a high resistance, and to set the device you short that resistance to level the charge with your signal, then arm the detector, which compares the capacitor charge with the sensor voltage and shouts if they change.
"Imp" wrote in news:xI5bg.8944$ snipped-for-privacy@news20.bellglobal.com:
Ok, well, we might be able to help you more if you said more about what you do want. Do you want to stop a thief? Or to stabilise a space station?
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Dunno if this is closer to what you're looking for, but pinball machines have long used a very simple device to detect a tilt. It's a long, thin metal rod with a weight on the end of it, surrounded by a conducting ring. It's essentially a pendulum that can swing in any direction. If the pendulum hits the ring, the alarm goes off. It's just a big switch.
What's more, you can adjust the sensitivity simply by adjusting the height of the pendulum. If you want more sensitivity, you lower the surrounding ring so that the very end of the pendulum will touch it. If you want the sensitivity to be less, then you move the surrounding ring further up the pendulum so that it must swing futher before touching.
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