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From: ehsjr on 14 Jun 2010 13:32
John Fields wrote:
> On 14 Jun 2010 04:08:08 -0700, Winfield Hill
> <Winfield_member(a)newsguy.com> wrote:
>
>
>>John Fields wrote...
>>
>>>Winfield Hill wrote:
>>>
>>>>John Fields wrote...
>>>>
>>>>>On Fri, 11 Jun 2010 07:02:03 -0500, John Fields wrote:
>>>>>
>>>>>>On 10 Jun 2010 13:23:55 -0700, Winfield Hill wrote:
>>>>>>
>>>>>>
>>>>>>>In a ringing bell application, as the supply voltage sags,
>>>>>>>and the amplitude drops, I imagine the circuit will move
>>>>>>>from class C back to class A operation, before stopping.
>>>>>>
>>>>>>Why imagine?
>>>>>>
>>>>>>Here's a circuit list that'll show it all _and_ it'll create
>>>>>>a .wav file, "bong.wav" in whatever folder the cicuit's in,
>>>>>>so you can hear it.
>>>>>>
>>>>>>Enjoy! :-)
>>>>>
>>>>>Oops... Here it is: [ big snip ]
>>>>
>>>>Thanks, John. I like the bong! [snip]
>>>
>>>---
>>>Sorry for the delay...
>>>
>>>Better yet, I chose a real-world inductor, included the specified
>>>parasitic R, and added, arbitrarily, an ohm as the ESR for the cap
>>>since I was too lazy to go shopping for that.
>>
>>Excellent.
>>
>>
>>>Here's the circuit, oscillating at around 675Hz.
>>>Sounds pretty good, I think, and the bong doesn't
>>>last as long as it used to.
>>
>>I didn't see, what did you change to lower the Q?
>
>
> ---
> The wire resistance of L1 and the ESR of C1.
> Right click on the components and a little dialogue will pop up which
> can be edited to modify the component attributes.
> ---
>
>
>>I had meant to suggest tying a series resistor on
>>Q1's emitter signal path.
>
>
> ---
> It does little more than attenuate the initial amplitude of the bong
> and disturb its symmetry, so the rate of decay seems to be controlled
> by the current C3 supplies into R2 and the base of Q3 after Q2 turns
> off.
>
> With C3 being 7.5�F and zero leakage, the range of decay varies from
> 1.9s with R2 open to 0.4s with R2 = 50k.
> ---
>
>
>>John Larkin commented that the ringdown was more
>>due to the LC's stored energy than Q1's amplifying
>>role. I wonder, if you took the same LC, ignore
>>your new secondary, leave out Q1, etc., and you
>>gave it a short current spike to get it started,
>>what would the result look like?
>
>
>
> Something like this, I'd suspect:
> ---
> Version 4
> SHEET 1 936 680
> WIRE -704 16 -752 16
> WIRE -592 16 -624 16
> WIRE -448 16 -512 16
> WIRE -448 64 -448 16
> WIRE -352 64 -448 64
> WIRE -448 80 -448 64
> WIRE -352 80 -352 64
> WIRE -752 96 -752 16
> WIRE -576 96 -576 64
> WIRE -448 176 -448 144
> WIRE -352 176 -352 160
> WIRE -352 176 -448 176
> WIRE -752 224 -752 176
> WIRE -576 224 -576 176
> WIRE -576 224 -752 224
> WIRE -528 224 -528 64
> WIRE -528 224 -576 224
> WIRE -448 224 -448 176
> WIRE -448 224 -528 224
> WIRE -752 320 -752 224
> FLAG -752 320 0
> SYMBOL ind2 -368 64 R0
> SYMATTR InstName L1
> SYMATTR Value 5.6e-3
> SYMATTR Type ind
> SYMBOL cap -464 80 R0
> SYMATTR InstName C1
> SYMATTR Value 10e-6
> SYMBOL voltage -752 80 R0
> WINDOW 123 0 0 Left 0
> WINDOW 39 0 0 Left 0
> WINDOW 0 -44 8 Left 0
> WINDOW 3 -26 108 Left 0
> SYMATTR InstName V2
> SYMATTR Value 5
> SYMBOL voltage -576 80 R0
> WINDOW 0 -45 9 Left 0
> WINDOW 3 -242 110 Invisible 0
> WINDOW 123 0 0 Left 0
> WINDOW 39 0 0 Left 0
> SYMATTR InstName V3
> SYMATTR Value PULSE(0 1 .1 1E-6 1E-6 1e-2)
> SYMBOL sw -496 16 M270
> WINDOW 0 32 15 Left 0
> WINDOW 3 32 44 Left 0
> SYMATTR InstName S1
> SYMBOL res -608 0 R90
> WINDOW 0 0 56 VBottom 0
> WINDOW 3 32 56 VTop 0
> SYMATTR InstName R1
> SYMATTR Value 1
> TEXT -672 256 Left 0 !.model SW SW(Ron=.01 Roff=1000Meg Vt=0.5Vh=0)
> TEXT -664 288 Left 0 !.tran 1 uic
>
> Zoom in on the current through R1 at about 1ms and you'll see smething
^
100ms
> pretty neat. :-)
>
> JF

Nice.

Ed
From: John Fields on 14 Jun 2010 20:44
On Mon, 14 Jun 2010 13:32:36 -0400, ehsjr <ehsjr(a)nospamverizon.net>
wrote:

>John Fields wrote:
>> On 14 Jun 2010 04:08:08 -0700, Winfield Hill
>> <Winfield_member(a)newsguy.com> wrote:
>>
>>
>>>John Fields wrote...
>>>
>>>>Winfield Hill wrote:
>>>>
>>>>>John Fields wrote...
>>>>>
>>>>>>On Fri, 11 Jun 2010 07:02:03 -0500, John Fields wrote:
>>>>>>
>>>>>>>On 10 Jun 2010 13:23:55 -0700, Winfield Hill wrote:
>>>>>>>
>>>>>>>
>>>>>>>>In a ringing bell application, as the supply voltage sags,
>>>>>>>>and the amplitude drops, I imagine the circuit will move
>>>>>>>>from class C back to class A operation, before stopping.
>>>>>>>
>>>>>>>Why imagine?
>>>>>>>
>>>>>>>Here's a circuit list that'll show it all _and_ it'll create
>>>>>>>a .wav file, "bong.wav" in whatever folder the cicuit's in,
>>>>>>>so you can hear it.
>>>>>>>
>>>>>>>Enjoy! :-)
>>>>>>
>>>>>>Oops... Here it is: [ big snip ]
>>>>>
>>>>>Thanks, John. I like the bong! [snip]
>>>>
>>>>---
>>>>Sorry for the delay...
>>>>
>>>>Better yet, I chose a real-world inductor, included the specified
>>>>parasitic R, and added, arbitrarily, an ohm as the ESR for the cap
>>>>since I was too lazy to go shopping for that.
>>>
>>>Excellent.
>>>
>>>
>>>>Here's the circuit, oscillating at around 675Hz.
>>>>Sounds pretty good, I think, and the bong doesn't
>>>>last as long as it used to.
>>>
>>>I didn't see, what did you change to lower the Q?
>>
>>
>> ---
>> The wire resistance of L1 and the ESR of C1.
>> Right click on the components and a little dialogue will pop up which
>> can be edited to modify the component attributes.
>> ---
>>
>>
>>>I had meant to suggest tying a series resistor on
>>>Q1's emitter signal path.
>>
>>
>> ---
>> It does little more than attenuate the initial amplitude of the bong
>> and disturb its symmetry, so the rate of decay seems to be controlled
>> by the current C3 supplies into R2 and the base of Q3 after Q2 turns
>> off.
>>
>> With C3 being 7.5�F and zero leakage, the range of decay varies from
>> 1.9s with R2 open to 0.4s with R2 = 50k.
>> ---
>>
>>
>>>John Larkin commented that the ringdown was more
>>>due to the LC's stored energy than Q1's amplifying
>>>role. I wonder, if you took the same LC, ignore
>>>your new secondary, leave out Q1, etc., and you
>>>gave it a short current spike to get it started,
>>>what would the result look like?
>>
>>
>>
>> Something like this, I'd suspect:
>> ---
>> Version 4
>> SHEET 1 936 680
>> WIRE -704 16 -752 16
>> WIRE -592 16 -624 16
>> WIRE -448 16 -512 16
>> WIRE -448 64 -448 16
>> WIRE -352 64 -448 64
>> WIRE -448 80 -448 64
>> WIRE -352 80 -352 64
>> WIRE -752 96 -752 16
>> WIRE -576 96 -576 64
>> WIRE -448 176 -448 144
>> WIRE -352 176 -352 160
>> WIRE -352 176 -448 176
>> WIRE -752 224 -752 176
>> WIRE -576 224 -576 176
>> WIRE -576 224 -752 224
>> WIRE -528 224 -528 64
>> WIRE -528 224 -576 224
>> WIRE -448 224 -448 176
>> WIRE -448 224 -528 224
>> WIRE -752 320 -752 224
>> FLAG -752 320 0
>> SYMBOL ind2 -368 64 R0
>> SYMATTR InstName L1
>> SYMATTR Value 5.6e-3
>> SYMATTR Type ind
>> SYMBOL cap -464 80 R0
>> SYMATTR InstName C1
>> SYMATTR Value 10e-6
>> SYMBOL voltage -752 80 R0
>> WINDOW 123 0 0 Left 0
>> WINDOW 39 0 0 Left 0
>> WINDOW 0 -44 8 Left 0
>> WINDOW 3 -26 108 Left 0
>> SYMATTR InstName V2
>> SYMATTR Value 5
>> SYMBOL voltage -576 80 R0
>> WINDOW 0 -45 9 Left 0
>> WINDOW 3 -242 110 Invisible 0
>> WINDOW 123 0 0 Left 0
>> WINDOW 39 0 0 Left 0
>> SYMATTR InstName V3
>> SYMATTR Value PULSE(0 1 .1 1E-6 1E-6 1e-2)
>> SYMBOL sw -496 16 M270
>> WINDOW 0 32 15 Left 0
>> WINDOW 3 32 44 Left 0
>> SYMATTR InstName S1
>> SYMBOL res -608 0 R90
>> WINDOW 0 0 56 VBottom 0
>> WINDOW 3 32 56 VTop 0
>> SYMATTR InstName R1
>> SYMATTR Value 1
>> TEXT -672 256 Left 0 !.model SW SW(Ron=.01 Roff=1000Meg Vt=0.5Vh=0)
>> TEXT -664 288 Left 0 !.tran 1 uic
>>
>> Zoom in on the current through R1 at about 1ms and you'll see smething
> ^
> 100ms
>> pretty neat. :-)
>>
>> JF
>
>Nice.
>
>Ed

---
Aarghhhh!!!

Good catch, thanks. :-)

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