low power, HV-in regulator with depletion mosfet

On Monday, June 3, 2013 4:08:48 PM UTC-4, Phil Hobbs wrote:
> On 06/03/2013 03:36 PM, bloggs.fredbloggs.fred@gmail.com wrote:
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> > On Monday, June 3, 2013 3:16:47 PM UTC-4, Phil Hobbs wrote:
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> >
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> >>
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> >> No, you do not want to do that.  If the load gets disconnected,
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> >> you'll
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> >>
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> >> be sourcing current into the output of the 78Lxx.  The input will
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> >> likely
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> >>
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> >> rise until Bad Things Happen.  You'd have to add another zener at
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> >> the
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> >>
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> >> output to prevent this, at which point you have 8 parts instead of
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> >> the
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> >>
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> >> original 4.
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> >
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> > That's what Ra2 is about, to sink the zener (or whatever is used)
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> > bias current. You're no more likely to require an OVP clamp in this
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> > circuit as in any other 78LXX circuit.
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> >
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> >
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> >>
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> >>
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> >>
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> >> BTW 78Lxx devices _stink_.  Their ripple rejection is horrible
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> >> compared
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> >>
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> >> to the 78xx or LM317L.  I used to use them occasionally, having
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> >> beguiled
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> >>
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> >> myself into thinking that they were just low-power 78xx, but then
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> >> I
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> >>
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> >> actually read the datasheet. :(
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> >
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> > That is probably another non-issue here taken care of by the choice
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> > of input side capacitor to the 78LXX. The FET is operating in its
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> > active region so I would expect at least a few 10s of K-Ohms
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> > impedance between the HV+ and the 78LXX input.
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> >
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> > It's good to nitpick all the various failure mechanisms of any
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> > circuit, but just don't try to make out that the original Larkin
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> > kluge is some kind of failsafe innovation when it is even more
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> > vulnerable to failure than this one.
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> >
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> > Figure 8 http://www.ti.com/lit/ds/symlink/lm78l12.pdf is showing a
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> > ripple rejection of 60dB flat out to 20KHz or something, at 5V
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> > differential, not spectacular, but not real bad either. Maybe you
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> > didn't have enough headroom in your measurement circuit?
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> >
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> I don't have a dog in this fight.  JL's circuit was a reworked version=20
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> of one dating back to the tube days, as he said himself, and similar=20
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> ones have appeared in every one of those interminable Circuits=20
>=20
> Encyclopedias that people used to publish.  (I had to buy a bunch of=20
>=20
> those a couple of years ago, in order to cite them as prior art against=
=20
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> a really dumb patent.  They're even more horrible than I remembered.)
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> The tube version would have been a lot more robust against transients=20
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> and shorts and stuff, but its regulation would have been very poor by=20
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> modern standards.
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> Why not discuss circuits, rather than getting into pissing contests?  I=
=20
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> mean, it's not as though Figure 10 in the IXYS app note is your own=20
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> personal masterpiece or anything.
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> Back to the circuit.  Using a voltage divider to protect the regulator=20
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> requires fairly tight constraints on the component values vs the HV=20
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> voltage, and you haven't shown any values.  It also wastes a lot of=20
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> power in general.
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> A zener would be very much safer, would waste no (additional) power at=20
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> all in normal operation, and would protect against regulator failure as=
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> well.
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> And with all the HV transients potentially running round that circuit at=
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> turn-on, I wouldn't agree that it's unlikely to need an OVP clamp.
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> Shorting the HV supply to ground (e.g. some sensible tech discharging=20
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> the capacitors before working on the equipment) could be exciting as=20
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> well--inductive spikes everywhere, plus the usual 78xx failure mode when=
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> their inputs are shorted to ground.
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> Cheers
>=20
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> Phil Hobbs
>=20
>=20
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> --=20
>=20
> Dr Philip C D Hobbs
>=20
> Principal Consultant
>=20
> ElectroOptical Innovations LLC
>=20
> Optics, Electro-optics, Photonics, Analog Electronics
>=20
>=20
>=20
> 160 North State Road #203
>=20
> Briarcliff Manor NY 10510
>=20
>=20
>=20
> hobbs at electrooptical dot net
>=20
> http://electrooptical.net

There's also a slight gain function from the HV ripple developed across the=
 zener modulating Vgs of the FET. I'm not going to speculate about a bunch =
of what-if's as to what kind of environment the circuit has to tolerate, ju=
st too open ended. The original post said something about just 10mA load or=
 so and a 48V supply, so that means he can easily power limit his source to=
 something workable and eliminate all this crazy conjecture about spikes, b=
lown junctions, unlimited rise times, and megalithic energy storage reservo=
irs all over the place ready to unleash destruction.

On Mon, 03 Jun 2013 15:06:35 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 06/03/2013 12:42 PM, John Larkin wrote:
><snip>
>> Electronic designers need imagination, not to just conceive circuits, but also
>> to imagine all their hazards.
>
>Well, sorry to introduce discussion into this wonderfully artistic 
>pissing contest, 

Well, I am talking about electronics. 

>but I'll take that invitation.
>0.  As you already mentioned, the IXYS FETs don't have a pinchoff 
>voltage that's guaranteed to be high enough to accommodate the 78Lxx's 
>dropout voltage.

Yeah, that's the serious one. 78Lxx doesn't even specify a max
dropout, just a typ.

>
>1. The 78Lxx can't sink any significant current from its output, so as 
>Jamie or somebody mentioned, C2 had better not open up, or the 78Lxx is 
>liable to blow up when the HV is applied.
>
>2. The usual 78xx vulnerability to shorting the input to ground, if C2 
>is too big.
>
>3. No protection, and possible danger if the FET shorts.
>
>4. No HV supply reversal protection.
>
>Did I miss any?
>
>Cheers
>
>Phil Hobbs

I was thinking

The thermal shutdown of the 78L12 is defeated by the low in-out
voltage. So if the load is shorted, the depletion fet gets all the
heat and could unsolder itself. The "peak output current" spec of a
78L is 2.2 amps!

Shorting the load could blow the fet gate. Well, probably not.

The fet might do the RF oscillation thing.


-- 

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation

On Monday, June 3, 2013 4:32:17 PM UTC-4, Jamie wrote:

>   If the initial charge/transients on the drain to gate do
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> not damage the reg output, the elevated voltage could force the
>=20
> reg into an unloaded state on the input and cause the fet to
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> supply too much voltage for the reg input.

A very clear demonstration of your complete misunderstanding of circuit ope=
ration. As the 3-terminal unloads the FET, the source-gate junction reverse=
 biases turning the FET off. Since the 78LXX has approximately 3mA load ind=
ependent internal bias drain through its GND pin, FET leakage to the point =
of overvoltaging the regulator is out of the question.
=20
>=20
=20
>=20
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>   Just a thought..
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More like fantasy...

On Mon, 3 Jun 2013 11:55:49 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

>On Monday, June 3, 2013 12:29:10 PM UTC-4, Jim Thompson wrote:
>>
>> 
>> 
>> But, if you see problems, what don't you spell them out, rather than
>> 
>> bloviating?  You criticize others for being vague, yet you are the
>> 
>> most obtuse poster in this group.  Maybe it's you who is the "senile
>> 
>> old git", huh ?>:-}
>> 
>> 		
>> 
>>                                         ...Jim Thompson
>
>Larkin is throwing the typical "not invented by me" hissy-fit, how childish. There are any number of ways to make the Supertex circuit bullet-proof. This, or anything obviously equivalent to it, takes care of the "That's OK, but it probably doesn't guarantee the 78L12 dropout voltage" problem.
>Please view in a fixed-width font such as
>                Courier.
>
>.
>.            HV+
>.             |
>.             |
>.             +-----
>.             |     |
>.             |   [Ra1]
>.             |     |
>.             |     |
>.             |     |  +  V   -
>.             |_||  |    \ z
>.  depletion    ||--+-----|<|---
>.    FET       >||         \    |
>.             |                 |
>.             |                 |
>.             |    V   > V      |
>.             |  +  IO -  z  -  |
>.             |     -------     |
>.             |    |       |    |
>.             +----| 78LXX |----+----+---
>.             |    |       |    |    |
>.             |     -------     |    |
>.            ===       |       === [Ra2]
>.             |        |        |    |
>.             |        |        |    |
>.          ---+--------+--------+----+---
>.
>.
>.
>.

Lots of parts. And why use a depletion fet now that you have the gate
drive parts? Enhancement fets are cheaper.

This is simple:

V+-------+-----+
         |     |
         |     |
         |     |
         R     |
         |     |
         |     |
         |     d
         +----g   nfet, either kind
         |     s
         |     |
         Z     |
         |     +-------78L12----out
         |     |         |
         |     C        gnd
       gnd     |
              gnd





-- 

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation

On Monday, June 3, 2013 5:56:52 PM UTC-4, John Larkin wrote:

> 
> The thermal shutdown of the 78L12 is defeated by the low in-out
> 
> voltage. So if the load is shorted, the depletion fet gets all the
> 

Not the 78LXX, that would be defeated by low input voltage relative to GND, not relative to output.

On Mon, 03 Jun 2013 14:45:09 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:


>You quit thinking when you reply to my posts. That's silly.

---
There's very little thinking required to refute your nonsense, so my
replies may seem silly to you.

-- 
JF

On Monday, June 3, 2013 6:03:49 PM UTC-4, John Larkin wrote:
> On Mon, 3 Jun 2013 11:55:49 -0700 (PDT),
>=20
> bloggs.fredbloggs.fred@gmail.com wrote:
>=20
>=20
>=20
> >On Monday, June 3, 2013 12:29:10 PM UTC-4, Jim Thompson wrote:
>=20
> >>
>=20
> >>=20
>=20
> >>=20
>=20
> >> But, if you see problems, what don't you spell them out, rather than
>=20
> >>=20
>=20
> >> bloviating?  You criticize others for being vague, yet you are the
>=20
> >>=20
>=20
> >> most obtuse poster in this group.  Maybe it's you who is the "senile
>=20
> >>=20
>=20
> >> old git", huh ?>:-}
>=20
> >>=20
>=20
> >> 	=09
>=20
> >>=20
>=20
> >>                                         ...Jim Thompson
>=20
> >
>=20
> >Larkin is throwing the typical "not invented by me" hissy-fit, how child=
ish. There are any number of ways to make the Supertex circuit bullet-proof=
. This, or anything obviously equivalent to it, takes care of the "That's O=
K, but it probably doesn't guarantee the 78L12 dropout voltage" problem.
>=20
> >Please view in a fixed-width font such as
>=20
> >                Courier.
>=20
> >
>=20
> >.
>=20
> >.            HV+
>=20
> >.             |
>=20
> >.             |
>=20
> >.             +-----
>=20
> >.             |     |
>=20
> >.             |   [Ra1]
>=20
> >.             |     |
>=20
> >.             |     |
>=20
> >.             |     |  +  V   -
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> >.             |_||  |    \ z
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> >.  depletion    ||--+-----|<|---
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> >.    FET       >||         \    |
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> >.             |                 |
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> >.             |                 |
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> >.             |    V   > V      |
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> >.             |  +  IO -  z  -  |
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> >.             |     -------     |
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> >.             |    |       |    |
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> >.             +----| 78LXX |----+----+---
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> >.             |    |       |    |    |
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> >.             |     -------     |    |
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> >.            =3D=3D=3D       |       =3D=3D=3D [Ra2]
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> >.             |        |        |    |
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> >.             |        |        |    |
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> >.          ---+--------+--------+----+---
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> >.
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> >.
>=20
> >.
>=20
> >.
>=20
>=20
>=20
> Lots of parts. And why use a depletion fet now that you have the gate
>=20
> drive parts? Enhancement fets are cheaper.
>=20
>=20
>=20
> This is simple:
>=20
>=20
>=20
> V+-------+-----+
>=20
>          |     |
>=20
>          |     |
>=20
>          |     |
>=20
>          R     |
>=20
>          |     |
>=20
>          |     |
>=20
>          |     d
>=20
>          +----g   nfet, either kind
>=20
>          |     s
>=20
>          |     |
>=20
>          Z     |
>=20
>          |     +-------78L12----out
>=20
>          |     |         |
>=20
>          |     C        gnd
>=20
>        gnd     |
>=20
>               gnd
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
> --=20
>=20
>=20
>=20
> John Larkin         Highland Technology, Inc
>=20
>=20
>=20
> jlarkin at highlandtechnology dot com
>=20
> http://www.highlandtechnology.com
>=20
>=20
>=20
> Precision electronic instrumentation
>=20
> Picosecond-resolution Digital Delay and Pulse generators
>=20
> Custom laser drivers and controllers
>=20
> Photonics and fiberoptic TTL data links
>=20
> VME thermocouple, LVDT, synchro   acquisition and simulation

Looks like the main advantage to the original SuperTex circuit was that the=
 gate was tied to a tightly regulated node which in turn improves the rippl=
e reduction at the 78LXX input, making for a exponentially quieter circuit.=
 How about using the FET to make a nominal current source feeding a zener s=
hunt pre-regulator for the 78LXX, that's pretty simple. I don't think ultra=
-low power is a big consideration for a line operated circuit.

On Mon, 03 Jun 2013 09:42:09 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

>On Mon, 03 Jun 2013 09:29:10 -0700, Jim Thompson
><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>
>>On Mon, 03 Jun 2013 09:16:11 -0700, John Larkin
>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
>>
>>>On Mon, 03 Jun 2013 08:41:02 -0700, Jim Thompson
>>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>>>
>>>>On Mon, 03 Jun 2013 07:02:36 -0700, John Larkin
>>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
>>>>
>>>>>On Mon, 03 Jun 2013 09:35:49 -0400, Jamie
>>>>><jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>>>>>
>>>>>>John Larkin wrote:
>>>>>>
>>>>>>> On Sun, 2 Jun 2013 20:11:22 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com wrote:
>>>>>>> 
>>>>>>> 
>>>>>>>>On Saturday, June 1, 2013 1:52:53 PM UTC-4, John Larkin wrote:
>>>>>>>>
>>>>>>>>That's amateurish. See the write-up for Figure 10 and use a cheap $0.17 78L12 that gets you where you need to be.
>>>>>>>>http://www.ixys.com/Documents/AppNotes/IXAN0063.pdf
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> That's OK, but it probably doesn't guarantee the 78L12 dropout voltage. 
>>>>>>> 
>>>>>>> 
>>>>>>The gate being connected directly to the output with HV on the other 
>>>>>>side of the fet, does not give ma a warm and fuzzy feeling with
>>>>>>fast transients with all that miller, hope the caps don't fail.
>>>>>>
>>>>>>  I think that circuit needs a crowbar if that was ever seriously put in
>>>>>>use. Maybe plant some 1.5k or better type TVSes on those nodes.
>>>>>>
>>>>>>  I don't know if sims would reveal enough collateral damage, the models
>>>>>>in Ltspice seem to think they can operate beyond infinity.
>>>>>>
>>>>>>Just my opinon, don't pay no mind to me, just a foot hill hick.
>>>>>>
>>>>>>Jamie
>>>>>
>>>>>If Fred had bothered to check the part data sheets, and not just swallow
>>>>>appnotes intact, he would have seen that the Supertex thing is flakey.
>>>>>
>>>>>It has another big problem, two actually, but I'll, as fatheads Fred and Jim
>>>>>like to say, "leave it to the student" to figure out.
>>>>
>>>>Explain to us "fatheads" just how is it flakey [sic]?  (You misspelled
>>>>"flaky" :-)
>>>>
>>>>Which request you will ignore, because you fit the mantra, "Stupid is
>>>>as stupid does".
>>>>
>>>>I keep saying, and you, and many others, keep ignoring... the models
>>>>provided by LTspice are "more perfect than nature", and I've provided
>>>>examples.  If you want some assurance of circuit performance, seek out
>>>>models provided by the manufacturer, or a private source.  
>>>>
>>>>And also apply some mental reality checks.  Simulations are only as
>>>>valid as the quality of the models.  Fortunately, for me, I/C
>>>>foundries provide very accurate models, with a large support team to
>>>>validate their accuracy.  Jelly bean discrete part manufacturers
>>>>rarely do.
>>>>		
>>>>                                        ...Jim Thompson
>>>
>>>Sterling lecture. Now get practical and find the two additional problems (I've
>>>pointed out one already) with the Supertex 78L12 bootstrap.
>>>
>>>Hmmm, there could even be one more!
>>
>>Well!  As a start, Figure 10 says "78L05", NOT "78L12".  Displaying,
>>again, your deficiency in reading comprehension.
>
>
>Fred, not I, pointed to the Supertex figure and suggested using a 78L12.
>Interesting suggestion, coupled with a stupid insult.
>
>But that doesn't matter. The bootstrap, as shown, has several hazards with any
>78Lxx.
>
>>
>>But, if you see problems, what don't you spell them out, rather than
>>bloviating?  You criticize others for being vague, yet you are the
>>most obtuse poster in this group.  Maybe it's you who is the "senile
>>old git", huh ?>:-}
>>		
>>                                        ...Jim Thompson
>
>It's incredible that you can't see even one of the problems.


Instead of waving your hands in the air, why don't you tell us what is
wrong with the circuit?

>
>Electronic designers need imagination, not to just conceive circuits, but also
>to imagine all their hazards.

Na-a-a-aw!  Really!  I didn't know that >!-)

Quit whining and tell us what is wrong with the circuit.

Are allusions all you have to offer... besides condescending
Pecksniffian crap?
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| San Tan Valley, AZ 85140   Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

bloggs.fredbloggs.fred@gmail.com wrote:

> On Monday, June 3, 2013 4:32:17 PM UTC-4, Jamie wrote:
> 
> 
>>  If the initial charge/transients on the drain to gate do
>>
>>not damage the reg output, the elevated voltage could force the
>>
>>reg into an unloaded state on the input and cause the fet to
>>
>>supply too much voltage for the reg input.
> 
> 
> A very clear demonstration of your complete misunderstanding of circuit operation. As the 3-terminal unloads the FET, the source-gate junction reverse biases turning the FET off. Since the 78LXX has approximately 3mA load independent internal bias drain through its GND pin, FET leakage to the point of overvoltaging the regulator is out of the question.
>  
> 
>  
> 
>>
>>  Just a thought..
>>
> 
> 
> More like fantasy...
really?

   For someone that is always in trouble presenting their case, does
not seem to be in the right corner for making such assessments.

   I understand it very clearly, holes in it all over the place.

  Get real, take it like a man, drag queen or what ever you are.


  Jamie

On Mon, 03 Jun 2013 15:42:34 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Mon, 03 Jun 2013 09:42:09 -0700, John Larkin
><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
>
>>On Mon, 03 Jun 2013 09:29:10 -0700, Jim Thompson
>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>>
>>>On Mon, 03 Jun 2013 09:16:11 -0700, John Larkin
>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
>>>
>>>>On Mon, 03 Jun 2013 08:41:02 -0700, Jim Thompson
>>>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>>>>
>>>>>On Mon, 03 Jun 2013 07:02:36 -0700, John Larkin
>>>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
>>>>>
>>>>>>On Mon, 03 Jun 2013 09:35:49 -0400, Jamie
>>>>>><jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>>>>>>
>>>>>>>John Larkin wrote:
>>>>>>>
>>>>>>>> On Sun, 2 Jun 2013 20:11:22 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com wrote:
>>>>>>>> 
>>>>>>>> 
>>>>>>>>>On Saturday, June 1, 2013 1:52:53 PM UTC-4, John Larkin wrote:
>>>>>>>>>
>>>>>>>>>That's amateurish. See the write-up for Figure 10 and use a cheap $0.17 78L12 that gets you where you need to be.
>>>>>>>>>http://www.ixys.com/Documents/AppNotes/IXAN0063.pdf
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> That's OK, but it probably doesn't guarantee the 78L12 dropout voltage. 
>>>>>>>> 
>>>>>>>> 
>>>>>>>The gate being connected directly to the output with HV on the other 
>>>>>>>side of the fet, does not give ma a warm and fuzzy feeling with
>>>>>>>fast transients with all that miller, hope the caps don't fail.
>>>>>>>
>>>>>>>  I think that circuit needs a crowbar if that was ever seriously put in
>>>>>>>use. Maybe plant some 1.5k or better type TVSes on those nodes.
>>>>>>>
>>>>>>>  I don't know if sims would reveal enough collateral damage, the models
>>>>>>>in Ltspice seem to think they can operate beyond infinity.
>>>>>>>
>>>>>>>Just my opinon, don't pay no mind to me, just a foot hill hick.
>>>>>>>
>>>>>>>Jamie
>>>>>>
>>>>>>If Fred had bothered to check the part data sheets, and not just swallow
>>>>>>appnotes intact, he would have seen that the Supertex thing is flakey.
>>>>>>
>>>>>>It has another big problem, two actually, but I'll, as fatheads Fred and Jim
>>>>>>like to say, "leave it to the student" to figure out.
>>>>>
>>>>>Explain to us "fatheads" just how is it flakey [sic]?  (You misspelled
>>>>>"flaky" :-)
>>>>>
>>>>>Which request you will ignore, because you fit the mantra, "Stupid is
>>>>>as stupid does".
>>>>>
>>>>>I keep saying, and you, and many others, keep ignoring... the models
>>>>>provided by LTspice are "more perfect than nature", and I've provided
>>>>>examples.  If you want some assurance of circuit performance, seek out
>>>>>models provided by the manufacturer, or a private source.  
>>>>>
>>>>>And also apply some mental reality checks.  Simulations are only as
>>>>>valid as the quality of the models.  Fortunately, for me, I/C
>>>>>foundries provide very accurate models, with a large support team to
>>>>>validate their accuracy.  Jelly bean discrete part manufacturers
>>>>>rarely do.
>>>>>		
>>>>>                                        ...Jim Thompson
>>>>
>>>>Sterling lecture. Now get practical and find the two additional problems (I've
>>>>pointed out one already) with the Supertex 78L12 bootstrap.
>>>>
>>>>Hmmm, there could even be one more!
>>>
>>>Well!  As a start, Figure 10 says "78L05", NOT "78L12".  Displaying,
>>>again, your deficiency in reading comprehension.
>>
>>
>>Fred, not I, pointed to the Supertex figure and suggested using a 78L12.
>>Interesting suggestion, coupled with a stupid insult.
>>
>>But that doesn't matter. The bootstrap, as shown, has several hazards with any
>>78Lxx.
>>
>>>
>>>But, if you see problems, what don't you spell them out, rather than
>>>bloviating?  You criticize others for being vague, yet you are the
>>>most obtuse poster in this group.  Maybe it's you who is the "senile
>>>old git", huh ?>:-}
>>>		
>>>                                        ...Jim Thompson
>>
>>It's incredible that you can't see even one of the problems.
>
>
>Instead of waving your hands in the air, why don't you tell us what is
>wrong with the circuit?
>
>>
>>Electronic designers need imagination, not to just conceive circuits, but also
>>to imagine all their hazards.
>
>Na-a-a-aw!  Really!  I didn't know that >!-)
>
>Quit whining and tell us what is wrong with the circuit.
>
>Are allusions all you have to offer... besides condescending
>Pecksniffian crap?
>		
>                                        ...Jim Thompson

OK, you give up.

I listed my concerns about an hour before you posted this. 


-- 

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation