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Date:	Fri, 16 Feb 2018 16:10:36 +0100
From:	mhx AT iae DOT nl
To:	geda-user AT delorie DOT com
Subject:	Re: [geda-user] (Off-topic) Question wrt driving HV piezo transducer
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On 2018-02-16 12:38, Richard Rasker (rasker AT linetec DOT nl) [via 
geda-user AT delorie DOT com] wrote:
> Hello Marcel,
> 
> Op 16-02-18 om 06:32 schreef mhx AT iae DOT nl:
>> On 2018-02-15 23:02, Richard Rasker (rasker AT linetec DOT nl) [via 
>> geda-user AT delorie DOT com] wrote:
[..]
> For all clarity, I attached the schematic, also because there's
> something else I don't understand: the top MOSFET (Q1) doesn't get the
> burst frequency at all, just the 1.5 ms LF pulses. The bottom one (Q2)
> is supplied with the burst signal as expected.

That must indeed be wrong. But there is something else, the top and 
bottom driver
want 180 degrees out of phase signals. An inverter seems to be missing, 
or
the two exors are wired differently than you think?
[https://wwwee.ee.bgu.ac.il/~pemic/publications/jour3.pdf]

> I carefully checked this against the schematic I was given, and I'm
> positive that I didn't make a mistake here. Could this be a mistake on
> behalf of the original designer? I contacted the supplier, but they
> couldn't tell me anything. Or perhaps Q1 is 'automatically' syncing to
> Q2 via changing voltage levels on the drain? I can't really see this
> happening in any reliable way...

No, this looks like a push-pull allright. Are those two 1uF caps not 
connected
to the center tap? The electrolytic 4700uF might not like the very large 
AC ripple.

> BTW, the circuit isn't really designed for resonance, as the 41 kHz
> given is in reality a selectable frequency between 3 kHz and 300 kHz,
> with 41 kHz being just one of the settings.

That is certainly going to blow when built like this, then. To make it 
work
between 3 and 300 kHz should be impossible. With that specification 
you'll want a
linear amplifier. With a dutycycle of 1.5ms/10s = 1:6666, dissipation is
not the issue, when the SOAR of the devices is respected.

[..]

-marcel

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