Twin T circuit wanted
in [Basics]
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From: default on 6 Jun 2010 08:19 On Sat, 05 Jun 2010 12:17:03 -0500, "krw(a)att.bizzzzzzzzzzzz" <krw(a)att.bizzzzzzzzzzzz> wrote: >On Sat, 05 Jun 2010 12:59:28 -0400, default <default(a)defaulter.net> wrote: > >>On Sat, 05 Jun 2010 10:55:09 -0500, "krw(a)att.bizzzzzzzzzzzz" >><krw(a)att.bizzzzzzzzzzzz> wrote: >> >>>On Sat, 05 Jun 2010 10:49:18 -0400, default <default(a)defaulter.net> wrote: >>> >>>>On Sat, 05 Jun 2010 09:54:04 -0400, Jamie >>>><jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote: >>>> >>>>>default wrote: >>>>>> Can someone supply a single transistor circuit that will give a damped >>>>>> sine wave when a pulse is applied? to emulate a bell sound >>>>>Damped? Do you mean compressed to a sequare wave? >>>>> >>>>> >>>>> You can do a 180 degree phase shift in a double T RC network how >>>>>ever, that produces a sine wave. etc.. >>>>> >>>>> >>>>> >>>>> >>>>> Feed back --||---+---||----+---||-----Base of tranny.. >>>>> | | >>>>> | | >>>>> R R >>>>> | | >>>>> com com >>>>> >>>>>ect. >>>>> >>>>> >>>>> >>>>Damped as in decaying, just like a bell. >>>> >>>>Seems to me John Larkin or Jim Thompson posted something like this a >>>>long time ago. Searching didn't find exactly what I want. I'm >>>>building a set of mechanical chimes but wanted something to use until >>>>I work out the kinks - and test the pic timing. >>> >>>If you've got a PIC, why not use it? >> >>The pic is just putting out de multiplexed pulses (only 4 outputs on >>the chip expanded to 12) to operate solenoids to strike chimes. Pics >>don't make sine waves very well without a lot of extra effort. The >>end goal is a mechanical chime system that can be programmed for >>different melodies. > >If all you're doing is debugging (getting the timing right), just PWM the >chimes. Even a PIC oughta be able to handle that. It'll do pwm easily. A bell is a decaying sine wave (or two or three). frequency constant (although the harmonic mix may change as it rings) with the amplitude decreasing. Sine wave is necessary for a good (clean) sound. > >>I have a goal in mind, I'm not interested in changing the goal, and >>this is just a little side excursion to aid in testing. > >Right, so use the PIC, then throw away the code. It's often easier than >building hardware, to be thrown away. Yeah I guess. The project is intended for a specific purpose, but I figure I might just keep the test set and use it as a unique doorbell. Who wants to listen to boring Westminster chimes when you can have something like "Pictures at an Exhibition?" or something different each time it is used? The ultimate goal is not to make noise - but to drive actual chime bars mechanically. I'm finding home-made strikers more of a challenge than I thought they would be. --
From: default on 6 Jun 2010 08:41 On Sat, 05 Jun 2010 10:06:01 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Sat, 05 Jun 2010 10:49:18 -0400, default <default(a)defaulter.net> >wrote: > >>On Sat, 05 Jun 2010 09:54:04 -0400, Jamie >><jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote: >> >>>default wrote: >>>> Can someone supply a single transistor circuit that will give a damped >>>> sine wave when a pulse is applied? to emulate a bell sound >>>Damped? Do you mean compressed to a sequare wave? >>> >>> >>> You can do a 180 degree phase shift in a double T RC network how >>>ever, that produces a sine wave. etc.. >>> >>> >>> >>> >>> Feed back --||---+---||----+---||-----Base of tranny.. >>> | | >>> | | >>> R R >>> | | >>> com com >>> >>>ect. >>> >>> >>> >>Damped as in decaying, just like a bell. >> >>Seems to me John Larkin or Jim Thompson posted something like this a >>long time ago. Searching didn't find exactly what I want. I'm >>building a set of mechanical chimes but wanted something to use until >>I work out the kinks - and test the pic timing. > >I did a bell simulator once, but I used several, three or four, >damped-ringing LC resonators. A single one didn't sound very >bell-like. Turns out that bells have a number of nearby resonant >modes, each with not-quite harmonics. Complex. > >The thing I did drove loudspeakers in the bow of a ship to go >bong-bong-bong every 30 seconds in the fog, so a crew guy didn't have >to stand there all night whacking a bell. > >Why not use the PIC and a dac? The code would be interesting. > >John > I want the finished product to have mechanical chimes, the electronic bells (twelve, with the ability to strike 2-4 at the same time, or strike one while another is still ringing down) To get the timing for the music I thought a little excursion into electronic bells would be helpful, because the mechanical parts are unwieldy, and I haven't committed to a mechanical design I'm satisfied with - then I thought this might also make a killer doorbell . . . a bit of "mission creep" is setting in. --
From: default on 6 Jun 2010 08:45 On Sun, 06 Jun 2010 07:04:50 +1000, David Eather <eather(a)tpg.com.au> wrote: >On 5/06/2010 11:54 PM, Jamie wrote: >> default wrote: >>> Can someone supply a single transistor circuit that will give a damped >>> sine wave when a pulse is applied? to emulate a bell sound >> Damped? Do you mean compressed to a sequare wave? >> >> >> You can do a 180 degree phase shift in a double T RC network how ever, >> that produces a sine wave. etc.. >> >> >> >> >> Feed back --||---+---||----+---||-----Base of tranny.. >> | | >> | | >> R R >> | | >> com com >> >> ect. >> >> >> >> > >If you reduce the gain of the amplifier portion of the circuit you will >get what you want Yeah. I tried that with a square wave and fet amplitude control, with a little L-C massaging on the output it doesn't sound bad, but it is too much hardware. Seems to me, back in the day, they used single twin T oscillators to get the sounds of drums, base drum and tom-tom, as well as bells from fairly simple one transistor circuits. --
From: default on 6 Jun 2010 08:47 On Sat, 5 Jun 2010 10:09:05 -0700 (PDT), whit3rd <whit3rd(a)gmail.com> wrote: >On Jun 5, 5:42�am, default <defa...(a)defaulter.net> wrote: >> Can someone supply a single transistor circuit that will give a damped >> sine wave when a pulse is applied? to emulate a bell sound > >A good bell sound takes the first, third, and fifth harmonics (three >sine waves), with damping times of 1, 1/3, 1/5 respectively. >It can be done with three LC sections and some buffer amplification, >for the speaker drive. A good bell sound is made with large heavy pieces of metal. --
From: krw on 6 Jun 2010 11:09
On Sun, 06 Jun 2010 08:19:20 -0400, default <default(a)defaulter.net> wrote: >On Sat, 05 Jun 2010 12:17:03 -0500, "krw(a)att.bizzzzzzzzzzzz" ><krw(a)att.bizzzzzzzzzzzz> wrote: > >>On Sat, 05 Jun 2010 12:59:28 -0400, default <default(a)defaulter.net> wrote: >> >>>On Sat, 05 Jun 2010 10:55:09 -0500, "krw(a)att.bizzzzzzzzzzzz" >>><krw(a)att.bizzzzzzzzzzzz> wrote: >>> >>>>On Sat, 05 Jun 2010 10:49:18 -0400, default <default(a)defaulter.net> wrote: >>>> >>>>>On Sat, 05 Jun 2010 09:54:04 -0400, Jamie >>>>><jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote: >>>>> >>>>>>default wrote: >>>>>>> Can someone supply a single transistor circuit that will give a damped >>>>>>> sine wave when a pulse is applied? to emulate a bell sound >>>>>>Damped? Do you mean compressed to a sequare wave? >>>>>> >>>>>> >>>>>> You can do a 180 degree phase shift in a double T RC network how >>>>>>ever, that produces a sine wave. etc.. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> Feed back --||---+---||----+---||-----Base of tranny.. >>>>>> | | >>>>>> | | >>>>>> R R >>>>>> | | >>>>>> com com >>>>>> >>>>>>ect. >>>>>> >>>>>> >>>>>> >>>>>Damped as in decaying, just like a bell. >>>>> >>>>>Seems to me John Larkin or Jim Thompson posted something like this a >>>>>long time ago. Searching didn't find exactly what I want. I'm >>>>>building a set of mechanical chimes but wanted something to use until >>>>>I work out the kinks - and test the pic timing. >>>> >>>>If you've got a PIC, why not use it? >>> >>>The pic is just putting out de multiplexed pulses (only 4 outputs on >>>the chip expanded to 12) to operate solenoids to strike chimes. Pics >>>don't make sine waves very well without a lot of extra effort. The >>>end goal is a mechanical chime system that can be programmed for >>>different melodies. >> >>If all you're doing is debugging (getting the timing right), just PWM the >>chimes. Even a PIC oughta be able to handle that. > >It'll do pwm easily. A bell is a decaying sine wave (or two or >three). frequency constant (although the harmonic mix may change as >it rings) with the amplitude decreasing. > >Sine wave is necessary for a good (clean) sound. Nonsense. You said you needed this for debug. It doesn't need to be perfect. If the PWM frequency is high enough... Store the waveform, if need be. >>>I have a goal in mind, I'm not interested in changing the goal, and >>>this is just a little side excursion to aid in testing. >> >>Right, so use the PIC, then throw away the code. It's often easier than >>building hardware, to be thrown away. > >Yeah I guess. The project is intended for a specific purpose, but I >figure I might just keep the test set and use it as a unique doorbell. >Who wants to listen to boring Westminster chimes when you can have >something like "Pictures at an Exhibition?" or something different >each time it is used? I'd rather hear nothing, but a simple "bong" beats them all. >The ultimate goal is not to make noise - but to drive actual chime >bars mechanically. I'm finding home-made strikers more of a challenge >than I thought they would be. |