cook@stout.ucar.edu (Forrest Cook) (07/20/89)
In article <790@serene.UUCP> gbell@pnet12.cts.com (Greg Bell) writes: >I'm wondering two things: What's the best/easiest way of making an electronic >doorbell? I'd prefer the attention-getting sound of a "ding-dong", that's why >I'm going to all this trouble. Greg, here is a possible solution that could be programmed to make many sounds: [oscillator]->[4040 counter]->[EPROM]->[DAC]->[low pass]->[amp]->[speaker] ^-----[flip flop]<---stop---| start----------^ You could store both the ding and the dong waveform as a sequence in the EPROM, which could drive the DAC and output a digitized waveform. Generate the desired wave form with a program and burn it into the EPROM. The low pass could be built into the amplifier. You could use an RS flip flop for the start/stop control, the button sets the flip flop, causing the oscillator to start and count through the wave table. You could use 7 bits for the DAC control and the 8th bit to reset the flip flop at the end of the pattern. A 27256 EPROM (32K X 8) would give you 4 seconds of sound at a sample rate of 8 Khz. There are many variations on this basic circuit, don't be afraid to experiment. A single chip micro could be substituted for the osc, counter, eprom, and start/stop logic. Personally, my doorbell is coupled into my "house computer" and causes a speech synthesizer to say "ding dong" in a mechanical sounding voice (SC-01). ^ ^ Forrest Cook - Beware of programmers who carry screwdrivers - LB /|\ /|\ cook@stout.ucar.edu (The preceeding was all my OPINION) /|\ /|\ {husc6|rutgers|ames|gatech}!ncar!stout!cook /|\ /|\ {uunet|ucbvax|allegra|cbosgd}!nbires!ncar!stout!cook
torkil@psivax.UUCP (Torkil Hammer) (07/21/89)
In article <790@serene.UUCP> gbell@pnet12.cts.com (Greg Bell) writes:
#
#I recently took on a somewhat dumb "home project". I wanted to build a
#door-bell extension since the downstairs bell isn't audible from upstairs.
#
Sears, Roebuck et Cetera (catalog sales) carries a cordless doorbell.
You mount a battery powered transmitter at any convenient point near the door
and plug in bell units in 110V outlets in the rooms where you want them.
Simple, flexible and convenient. Units are like $20 each.
The range is advertised as being something like 50 ft.
[I don't have one so I don't know how good they are.]
Of course it is not a hack. But if you want maximum credit for
minimum work at a modest expense that is the way to go.
have fun
torkilgene@cooper.cooper.EDU (Gene (the Spook) ) (07/21/89)
in article <790@serene.UUCP>, gbell@pnet12.cts.com (Greg Bell) says: > > I'm wondering two things: What's the best/easiest way of making an electronic > doorbell? I'd prefer the attention-getting sound of a "ding-dong", that's why > I'm going to all this trouble. In addition, how do the sine wave generators > that use the PTC of a particular light bulb work??? 1) You might try the piezo element, complete with "ding-dong" driver IC, that Radio Shark used to, and possibly still does, sell. Loudness is ok in a reasonably quiet room, but don't expect to hear it above your vacuum cleaner or power tools. 2) Those light bulbs act as variable resistances in a feedback network. To oscillate properly, the loop gain must be exactly unity. If it's less, the signal won't regenerate and it will die out; if it's more, the output will saturate and your sine wave will become badly distorted (chopped off at the extremes). You might want to try a ~wave-generator-in-a-chip like an XR2208 (Exar) or an 8048 (Intersil). Loads of fun. Spookfully yours, Gene
gbell@pnet12.cts.com (Greg Bell) (07/21/89)
cook@stout.ucar.edu (Forrest Cook) writes: >In article <790@serene.UUCP> gbell@pnet12.cts.com (Greg Bell) writes: >>I'm wondering two things: What's the best/easiest way of making an electronic >>doorbell? I'd prefer the attention-getting sound of a "ding-dong", that's why >>I'm going to all this trouble. > >Greg, here is a possible solution that could be programmed to make many sounds: > >[oscillator]->[4040 counter]->[EPROM]->[DAC]->[low pass]->[amp]->[speaker] > ^-----[flip flop]<---stop---| >start----------^ > >You could store both the ding and the dong waveform as a sequence in the >EPROM, which could drive the DAC and output a digitized waveform. >Generate the desired wave form with a program and burn it into the EPROM. I've thought of that, but thought there'd be a better/cheaper way of doing it... a more "conventional" way perhaps. It just so happens I have an A-D, D-A, some RAM, a monitor EPROM, and an 8031 sitting in breadboard form on my desk in front of me. I was basically trying to record sound and play it back. My goal is to have a telephone ringer that screams instead of rings 8-). Could do any number of other sounds too. Biggest problem is getting the audio digitized, and burned into an EPROM. My experimentation with A-D and D-A is producing questionable results. I really need to ad an anti-aliasing filter to the input, some low-pass on the output, and a sample and hold circuit. Problem is, I'm outta breadboard space! I need to wire-wrap the 8031 brain portion so I can free up the breadboarding sockets for more fooling around. Greg Bell_________________________________________________________ Hardware hacker | Electronics hobbyist | UUCP: uunet!serene!pnet12!gbell EE major at UC San Diego |
pec@necntc.nec.com (Paul Cohen) (07/21/89)
NEC has a line of speech generation components which can also be programmed to generate various tones of which a sine wave (up to about 3 KHz) would be the simplest example. DTMF signals are examples of somewhat more complex sounds that are possible. Code for the DTMF signals is available as a library. Since so many frequencies are possible, sine waves would have to be custom programmed, but this is not difficult. An open question for the readers of this news-group: what frequencies of sine waves do you want? We could add them to our library fairly easily. The parts, uPD775x (x = 5, 6, 7) come as mask ROM parts with various sizes of ROM. There is also a version, uPD7759 which uses external memory (RAM or ROM) and a one-time programmable version the uPD77P56. All of these parts include a D/A and filter circuitry and require only an external ceramic resonator for clocking. Call (508) 655-8833 or (800) 366-3782 for more information.
bill@videovax.tv.Tek.com (William K. McFadden) (07/22/89)
In article <790@serene.UUCP> gbell@pnet12.cts.com (Greg Bell) writes: >I recently took on a somewhat dumb "home project". I wanted to build a >door-bell extension since the downstairs bell isn't audible from upstairs. > >The easy way to do this would be to put another doorbell in series (or >parallel?) with the one downstairs. I tried both ways, but neither worked. >Either one bell would ring, or neither. But not both. In series there would too little voltage to operate (e.g., 12v each instead of 24v). In parallel they would probably have too little current (power xfmr too small). You can get this to work by doubling the voltage or current, respectively. I'd be in favor of doubling the transformer current and hooking them in parallel, since the other solution uses higher voltages (e.g., more dangerous). >So, I thought it would be fun to build a simple circuit that would sense the >drop across the xformer or bell downstairs and generate two sine waves in >sequence, each decreasing in volume (ie. "Ding-dong"). I know this is cheating, but Radio Shack has a beeper that does this (ding- dong, I mean, not sense the voltage drop). You would still have the challenge of designing the "voltage drop sensor." -- Bill McFadden Tektronix, Inc. P.O. Box 500 MS 58-639 Beaverton, OR 97077 UUCP: bill@videovax.Tek.com, {hplabs,uw-beaver,decvax}!tektronix!videovax!bill GTE: (503) 627-6920 "The biggest difference between developing a missle component and a toy is the 'cost constraint.'" -- John Anderson, Engineer, TI
gbell@pnet12.cts.com (Greg Bell) (08/15/89)
I recently took on a somewhat dumb "home project". I wanted to build a
door-bell extension since the downstairs bell isn't audible from upstairs.
The easy way to do this would be to put another doorbell in series (or
parallel?) with the one downstairs. I tried both ways, but neither worked.
Either one bell would ring, or neither. But not both.
So, I thought it would be fun to build a simple circuit that would sense the
drop across the xformer or bell downstairs and generate two sine waves in
sequence, each decreasing in volume (ie. "Ding-dong").
I didn't know what I was in for! Sine wave generators aren't too trivial. I
tried one using a 741 with a twin-T circuit in the feedback loop. This worked
OK, but was hard to tweak into working right. Also, making the amplitude
decrease turned out to be difficult.
I opened up National's Linear App book and found a zillion different sine wave
circuits.
I'm wondering two things: What's the best/easiest way of making an electronic
doorbell? I'd prefer the attention-getting sound of a "ding-dong", that's why
I'm going to all this trouble. In addition, how do the sine wave generators
that use the PTC of a particular light bulb work???
Greg Bell_________________________________________________________
Hardware hacker |
Electronics hobbyist | UUCP: uunet!serene!pnet12!gbell
EE major at UC San Diego |c37189h@saha.hut.fi (Suomalainen Harri Olavi) (09/05/89)
In article <790@serene.UUCP> gbell@pnet12.cts.com (Greg Bell) writes: > >I recently took on a somewhat dumb "home project". I wanted to build a >door-bell extension since the downstairs bell isn't audible from upstairs. You could do it with a extremely simple device: Rectify voltage your bell works with, smooth it with a capasitor and connect a piezo buzzer on it! --- E-mail: c37189h@saha.hut.fi * If you're feeling good, don't * UUCP: ...!mcvax!santra!saha!c37189h * worry - You'll get over it! *
ISW@cup.portal.com (Isaac S Wingfield) (09/07/89)
Greg Bell writes:
I'm going to all this trouble. In addition, how do the sine wave generators
that use the PTC of a particular light bulb work???
The light bulb's non-linear resistance is (hopefully) used to
control the amplitude of the oscillation to keep the amp in
it's linear region (necessary for good sines). Messers Hewlett
and Packard made a bunch of money off that kind of oscillator!
For the doorbell, try a big L-C set up for damped ringing (sorry)
Maybe you can synthesize the L from an op-amp.
Isaac isw@cup.portal.commyers@hpfcdj.HP.COM (Bob Myers) (09/09/89)
>Greg Bell writes: > >I'm going to all this trouble. In addition, how do the sine wave generators >that use the PTC of a particular light bulb work??? > >The light bulb's non-linear resistance is (hopefully) used to >control the amplitude of the oscillation to keep the amp in >it's linear region (necessary for good sines). Messers Hewlett >and Packard made a bunch of money off that kind of oscillator! Specifically, find a good reference to the "Wien-bridge" oscillator circuit; the bulb is used as one of the resistances in the resistive-divider side of the bridge, and so provides "automatic" amplitude adjustment. Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not Ft. Collins, Colorado | those of my employer or any other myers%hpfcla@hplabs.hp.com | sentient life-form on this planet.