Twin T circuit wanted
in [Basics]
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From: whit3rd on 5 Jun 2010 13:09 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.
From: John Larkin on 5 Jun 2010 13:06 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
From: krw on 5 Jun 2010 13:17 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. >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.
From: David Eather on 5 Jun 2010 17:04 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
From: Jasen Betts on 6 Jun 2010 06:00
On 2010-06-05, default <default(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 I once powered a CD4047 based oscilator driving a 50 ohm speaker from a 1000uF capacitor. it made a gong-like sound if you charged the capacitor and then used the capacitor to power the circuit. --- news://freenews.netfront.net/ - complaints: news(a)netfront.net --- |