On Wed, 19 Apr 2017 01:57:47 +0000 (UTC), bob prohaska
<bp@www.zefox.net> wrote:
>I recently bought a gas water heater and made a point of getting one
>that didn't require external electrical power to operate.
>
>To my astonishment, it nonetheless came with what behaves like a digital
>controller, complete with a green LED status light that must require close
>to 3 volts to turn on.
>
>The electronics are operated from a standard Honeywell thermopile generator
>producing 750 mV open circuit with a 3 ohm source impedance. I expected to
>find an explanation of how it's done via a quick Web search, but have so
>far come up with nothing very informative: Only that one can get MOSFET
>transistors "programmed", evidently by something like charge trapping,
>to have arbitrary gate threshold voltage, down to zero. That seems rather
>exotic for a water heater 8-)
>
>Can somebody point me to an application note explaining how this is done?
>
>Thanks for reading,
>
>bob prohaska
>
>
Google "energy harvesting" and/or "Joule thief"
just for entertainment.
w.
Reply by Phil Allison●April 20, 20172017-04-20
bob prohaska wrote:
>
> Phil Allison
> >>
> > ** The first LT device I linked came from " 700mV boost converter" and the LT3108 is mentioned at the top of the first LT page .
> >
> > Couldn't have been easier.
> >
> >
> 8-)
> "boost converter" never occurred to me......
>
** Shame on you - there simply had to be one of 'em in some form.
I didn't know specific thermopile input ones existed.
Using a 1:100 input tranny IS a neat idea.
.... Phil
Reply by bob prohaska●April 20, 20172017-04-20
Phil Allison <pallison49@gmail.com> wrote:
>>
> ** The first LT device I linked came from " 700mV boost converter" and the LT3108 is mentioned at the top of the first LT page .
>
> Couldn't have been easier.
>
>
8-)
"boost converter" never occurred to me......
thanks,
bob
Reply by bob prohaska●April 19, 20172017-04-19
John Larkin <jjlarkin@highland_snip_technology.com> wrote:
>
> That sounds like the Honeywell Frankenstat. It is powered by the
> thermocouple, probably with some sort of switching regulator voltage
> booster.
>
> They occasionally screw up, and there are Youtube videos about how to
> prevent it, and how to reset them after they throw an error.
>
> http://learnbyblogging.com/honeywell-water-heater-thermostat-woe-how-i-fixed-it/
>
>
Mine looks essentially the same, apart from color scheme. No battery, which
is good, but it sounds like reliability is an issue.
Once the warranty expires I'll likely have to become an expert.....
Thanks for writing,
bob prohaska
Reply by Phil Allison●April 19, 20172017-04-19
bob prohaska wrote:
> Phil Allison:
> >>
> >
> > ** Or this one, specially for thermopiles.
> >
> > http://cds.linear.com/docs/en/datasheet/3108fc.pdf
> >
> >
> > ..... Phil
> >
>
> That's plausible, it mentions Honeywell by name.
>
> What search terms did you use? I tried thermopile in
> various combinations and never came close....
>
>
** The first LT device I linked came from " 700mV boost converter" and the LT3108 is mentioned at the top of the first LT page .
Couldn't have been easier.
..... Phil
Reply by bob prohaska●April 19, 20172017-04-19
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
> I have one like that. There's a battery in the control box.
>
Hmm, I hope not. Nothing said in the (very skimpy) instructions
about batteries, but there could be a battery. The entire heater is
warranted only for six years, so a lithium coin cell as a backup
would have a long enough life.
Time will tell......
bob prohaska
That's plausible, it mentions Honeywell by name.
What search terms did you use? I tried thermopile in
various combinations and never came close....
Thank you!
bob prohaska
Reply by John Larkin●April 19, 20172017-04-19
On Wed, 19 Apr 2017 01:57:47 +0000 (UTC), bob prohaska
<bp@www.zefox.net> wrote:
>I recently bought a gas water heater and made a point of getting one
>that didn't require external electrical power to operate.
>
>To my astonishment, it nonetheless came with what behaves like a digital
>controller, complete with a green LED status light that must require close
>to 3 volts to turn on.
>
>The electronics are operated from a standard Honeywell thermopile generator
>producing 750 mV open circuit with a 3 ohm source impedance. I expected to
>find an explanation of how it's done via a quick Web search, but have so
>far come up with nothing very informative: Only that one can get MOSFET
>transistors "programmed", evidently by something like charge trapping,
>to have arbitrary gate threshold voltage, down to zero. That seems rather
>exotic for a water heater 8-)
>
>Can somebody point me to an application note explaining how this is done?
>
>Thanks for reading,
>
>bob prohaska
>
>
That sounds like the Honeywell Frankenstat. It is powered by the
thermocouple, probably with some sort of switching regulator voltage
booster.
They occasionally screw up, and there are Youtube videos about how to
prevent it, and how to reset them after they throw an error.
http://learnbyblogging.com/honeywell-water-heater-thermostat-woe-how-i-fixed-it/
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by Tim Wescott●April 19, 20172017-04-19
On Wed, 19 Apr 2017 01:57:47 +0000, bob prohaska wrote:
> I recently bought a gas water heater and made a point of getting one
> that didn't require external electrical power to operate.
>
> To my astonishment, it nonetheless came with what behaves like a digital
> controller, complete with a green LED status light that must require
> close to 3 volts to turn on.
>
> The electronics are operated from a standard Honeywell thermopile
> generator producing 750 mV open circuit with a 3 ohm source impedance. I
> expected to find an explanation of how it's done via a quick Web search,
> but have so far come up with nothing very informative: Only that one can
> get MOSFET transistors "programmed", evidently by something like charge
> trapping,
> to have arbitrary gate threshold voltage, down to zero. That seems
> rather exotic for a water heater 8-)
>
> Can somebody point me to an application note explaining how this is
> done?
>
> Thanks for reading,
>
> bob prohaska
I get 45mW from the thermopile -- that's enough to light up the LEDs in
interior light, and have enough left over to run a thrifty microprocessor.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
I'm looking for work -- see my website!
Reply by Phil Hobbs●April 19, 20172017-04-19
On 04/18/2017 09:57 PM, bob prohaska wrote:
> I recently bought a gas water heater and made a point of getting one
> that didn't require external electrical power to operate.
>
> To my astonishment, it nonetheless came with what behaves like a digital
> controller, complete with a green LED status light that must require close
> to 3 volts to turn on.
>
> The electronics are operated from a standard Honeywell thermopile generator
> producing 750 mV open circuit with a 3 ohm source impedance. I expected to
> find an explanation of how it's done via a quick Web search, but have so
> far come up with nothing very informative: Only that one can get MOSFET
> transistors "programmed", evidently by something like charge trapping,
> to have arbitrary gate threshold voltage, down to zero. That seems rather
> exotic for a water heater 8-)
>
> Can somebody point me to an application note explaining how this is done?
>
> Thanks for reading,
>
> bob prohaska
>
>
>
I have one like that. There's a battery in the control box.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net