Re: SillyAmp

Mar 23, 2007 7 Replies


>


>>Jim Thomps>>>
>>>>>> I thought about that last one as a replacement to the HV optos
>>>>>> when you first 'published' your idea here a couple of years ago.
>>>>>> But now that's 4 active parts. Well six, including the leds.
>>>
>>>> v+
>>>> |
>>>> |
>>>> r
>>>> |
>>>> +-----------out
>>>> |
>>>> | Supertex
>>>> d depletion-mode
>>>> in--/\\/\\---, g ---,
>>>> | s |
>>>> | | |
>>>> a c |
>>>> k ---> b |
>>>> | opto e |
>>>> | | |
>>>> gnd +-----+----- v-
>>>
>>>>> 3 parts total! And you can get low-voltage optos as duals, so
>>>>> you can make it full totem-pole, class B, 500 volts p-p out,
>>>>> with three parts!
>>>
>>>> Awesome. Don't forget a resistor for the opto.
>>>
>>>>> Apex, cry your heart out.
>>>>> John
>>>
>>> Another silly KYAG circuit ;-)
>>
>> ?? Really? KYAG? How so? ??
>
>Concern for opto NPN punch thru during power-up... I could go for a
>zener or some-such in there.
>
>> That looks like a relatively-well
>> behaved circuit, with excessive gain. But it does cry out for a
>> feedback loop.
>
>I've been musing really retro... maybe a mixed toob/silicon amplifier
>stage ;-)
>
> ...Jim Thompson

You want silly? How about a parametric amplifier using the nonlinearity of ceramic caps!


John



Bring it on! I'd love to see anything about parametric amplifers-- the only thing I can find on them is "they work by varying some part of the circuit"...drrrrr...okay...

Ceramic caps would be a very accessible way to demonstrate one.

Tim

-- Deep Fryer: A very philosophical monk. Website @

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see if you can find anything on a "paraformer". Wanlass & Wanlass dreamed it up when I was an itch in my daddy's pants IIRC.

the trick was to get a tap-wound C core, and cut it in half, then rotate one half 90 degrees ?! The flux from one wouldnt couple to the other, but it would modulate the permeability....

Cheers Terry

I couldn't make sense of that so I had a look.

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is probably what you were speaking about.

That one works because there's an additional *shared* piece of core (flat plate between both C halves) that sees the two orthogonal fluxes, hence it has its permeability modulated by one winding without influencing the other.

Thanks, Fred.

fun stuff eh Fred?

It was a long time ago I looked at the paraformer, but Im pretty sure it was as I described it. I was interested in magamps at the time....

Cheers Terry

I've seen that applied to a toroid. Normal toroidal windings, with another winding across the outside of everything. The outside winding was supposed to reduce the permeability. I still don't know whether it was an April Fool's or not.

Tony Williams.

My first thought was that they're related, but mag amps windings are coupled.

I still can't see how you can arrange 2 C cores halves to achieve permeability modulation.

I've posted on abse another arrangement that can be used with 2 identical 'C' cores. But the C is almost closed.

Thanks, Fred.

Tony Williams a écrit :

I've seen that too. A more effective way is to make the toroid hollow (for ex. 2 C halves used as the toroid section) so that both flux path are closed.

I've also seen, when searching about flux gates, some ways of making 3 orthogonal fluxes within one core. Can't remember what they were used for.

Thanks, Fred.

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