First idea:

Eliminate a lot of the electrical energy required by powering the mixing
actuator hydraulically using mechanical amplification.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

----- Original Message -----
From: "Gennette, Bruce" <bruce.gennette@TAFE.NSW.EDU.AU>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Tuesday, May 01, 2001 8:08 PM
Subject: [PIC]: Project Idea :- Water Mixer Controller (Temperature)


> Project Idea :-  Water  Mixer  Controller  (Temperature)
>
> A small, cheap, modular device to automatically adjust the mixing of hot
and
> cold water to produce a desired water temperature when a mixer valve is
> opened.
>
> Applications :-
> Domestic - pre-set bath temperatures for babies, children and elderly,
> pre-set dishwashing water temperature, pre-set washing machine
> temperature(s), etc.
> Industrial - car wash, process control, . . . actually lots and lots of
auto
> temperature applications, and not just for water (how about mixing hot and
> cold fuel to the optimum injector temperature?).
>
> Features :-
> Powered by the temperature differential in the two input streams.
> Controller easily replaced WITHOUT dismantling the tap (faucet for the
> Americans)
> Software to be fault tolerant, supply water temperature variation tolerant
> and FAIL SAFE.
>
> First Thoughts :-
> * Powered by a thermopile (series of thermocouples) in the supply streams
> feeding into a super cap. [Mounted semi-permanently in the tap]
> * Input / Output monitoring by thermocouples.
> * Output monitored by a small bellows which trips an over-ride spring if
too
> hot (re-set button required).
> * Controls a solenoid by pwm through a H-bridge to drive it to any of
> thousands of positions. The solenoid moves the middle plate in a ceramic
> slide gate to control the mixing of the two streams. (Ceramic slide gates
> have high friction, so will remain in place without needing the H-bridge
to
> hold the 'set' position) . [Mounted semi-permanently in the tap]
> * PIC to monitor and control the whole system. [Mounted in a socket at the
> rear of the tap]
> * Long-life, rechargeable, low power battery built into PIC module.
>
>
> Electronics Desired (whished for?) :-
> A low voltage microcontroller with at least 2 analog inputs, 2 outputs
> (operate the failsafe and to charge the battery) and a pwm H-bridge
output.
> Standby power source (battery), solenoid operating power source
(thermopile)
> and power storage device (super cap).
>
>
> Any thoughts Piclisters ?
>
> I can see a market for billions of these if it is possible to make them
> cheaply enough.
>
> Bye.
>
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>

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