Maker Pro
Maker Pro

Bells and G Forces

R

Ryan

Jan 1, 1970
0
I'm looking into the idea of home growing a door chime beginning with a
magnet switch on a door. (All the wireless kind I've seen have crap
range and only one receiver and no visual alert.)

I want to make one audio chime and then in a more distant location, make
a second audio chime with a light too.

As a beginner, and sometimes slightly more than that, I'm not sure what
methods exist to activate a short "ding" or electrical pulse that
doesn't continue through the duration of time that the door is open.


~

On another topic, I am interested in measuring G force with
acceleration. I've searched around a little bit, but would appreciate
a pointer in the right direction.

I'm wondering the name of a circuit/device that can be used measure
change in velocity. I'm curious how difficult it is (for an
electronics non-genious) to take measurements / read voltages / design
circuits based on the outputs of this device.

The maximum expected change in velocity is about 15 feet per second per
second.


Thank you.
 
S

Stephen J. Rush

Jan 1, 1970
0
I'm looking into the idea of home growing a door chime beginning with a
magnet switch on a door. (All the wireless kind I've seen have crap
range and only one receiver and no visual alert.)

I want to make one audio chime and then in a more distant location, make
a second audio chime with a light too.

As a beginner, and sometimes slightly more than that, I'm not sure what
methods exist to activate a short "ding" or electrical pulse that
doesn't continue through the duration of time that the door is open.


~

On another topic, I am interested in measuring G force with
acceleration. I've searched around a little bit, but would appreciate
a pointer in the right direction.

I'm wondering the name of a circuit/device that can be used measure
change in velocity. I'm curious how difficult it is (for an
electronics non-genious) to take measurements / read voltages / design
circuits based on the outputs of this device.

The maximum expected change in velocity is about 15 feet per second per
second.


Thank you.

A "one-shot" is a device that generates a single pulse when triggered.
There are many circuits, but the simplest way to generate a pulse when a
switch closes is to put a capacitor in series with the load. The
combination draws a pulse of current, then looks like an open circuit once
the capacitor is fully charged. If the load is the coil of a small relay,
you can drive a bigger load without needing an inconveniently large
capacitor. You will need some path for the capacitor to discharge
through when the switch opens, such as a parallel resistor.

A gadget that measures acceleration is called an accelerometer.
Tiny solid-state ones are made, but I haven't looked up the prices lately.
If you don't need accurate calibration, it's fun to experiment with
homebrew approaches, such as a mass on as spring with some way to measure
the deflection, or a phonograph cartridge (Do they still make cheap ones?
It might be easier to buy an old turntable at a thrift store.) with a
small mass attached to the stylus, or maybe a U-tube with colored water
and an optical liquid-level detector. The acceleration you mention is
about half a gee, so you don't need great sensitivity.
 
B

Bob Masta

Jan 1, 1970
0
On Fri, 23 Feb 2007 04:03:00 -0500, "Stephen J. Rush"

A gadget that measures acceleration is called an accelerometer.
Tiny solid-state ones are made, but I haven't looked up the prices lately.
If you don't need accurate calibration, it's fun to experiment with
homebrew approaches, such as a mass on as spring with some way to measure
the deflection, or a phonograph cartridge (Do they still make cheap ones?
It might be easier to buy an old turntable at a thrift store.) with a
small mass attached to the stylus, or maybe a U-tube with colored water
and an optical liquid-level detector. The acceleration you mention is
about half a gee, so you don't need great sensitivity.

If you are just experimenting, and don't need small size, you
might want to try a speaker as the mass-on-a-spring sensor.
You will need to attach the desired (non-ferrous) mass to the center
of the cone. Measure the response from the speaker terminals.
This system will measure acceleration along the axis of the
speaker; the speaker suspension prevents motion in other
directions.

Best regards,


Bob Masta

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!
 
J

JeffM

Jan 1, 1970
0
Ryan said:
I'm looking into the idea of home growing a door chime
beginning with a magnet switch on a door.[...]
The switch doesn't move and is not mounted on the door.
I'm not sure what methods exist to activate a short "ding"[...]
that doesn't continue through the duration of time that the door is open.
Space the switch off the door frame so that the magnet PASSES it.
Use normally open contacts or invert the state.
 
G

Gareth

Jan 1, 1970
0
Ryan wrote:

[SNIP]
On another topic, I am interested in measuring G force with
acceleration. I've searched around a little bit, but would appreciate
a pointer in the right direction.

I'm wondering the name of a circuit/device that can be used measure
change in velocity.
Accelerometer

I'm curious how difficult it is (for an
electronics non-genious) to take measurements / read voltages / design
circuits based on the outputs of this device.
Have a look at some of the datasheets and see what you think. I think
that in the simplest form they just produce a voltage proportional to
acceleration. Others give out pulses with different duty cycle
proportional to acceleration.

Analog Devices make small accelerometers,

http://www.analog.com/en/subCat/0,2879,764%5F800%5F0%5F%5F0%5F,00.html

Freescale have a range of similar devices

http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=0112691118


--
 
Top