Re: Liquid level indicator

Hi Chris

I did once get the .pdf from Maplin that you refer to. It's just a
scan of the instructions which come with the module - assuming you have
the same file. Perhaps I'm learning some of this electronics lark as I
too came to the conclusion that I wouldn't be able to drive my relay
from the tiny current available from the module.

I assumed that a Darlington pair would help me out here. Is there any
reason why you suggest the NPN-PNP cct in particular?

The temperature control is definitely a luxury thing, and by the look
of things is best left until version 2 of this setup which is already
tring to achieve a lot.

The heating side of things I can see getting used in two ways -
1.) To perform stepped mashes - only for a tiny proportion of brews
(luxury)
2.) To keep the wort at a set temperature when recirculating - losses
may occur at the pump and in the pipework.

I have heard about homebrew systems existing called RIMS (RecIrculating
Mash System) and HERMS (HEated Recirculating Mash System), and they
rely recirculating the wort and for HERMS, heating it at the same time,
so it must be possible.

The pump will be pumping the liquid at all times when the heater is on,
so the liquid shouldn't be in contact with the heater element for any
length of time, so the liquid temperature level should be rising very
slowly and steadily with any luck, but perhaps you're right, manual
control and a normal glass thermometer may well be a better solution.
But it's not very geeky, is it! :)

There's two things which need to happen heat wise;
1). The heat of the liquid in the container must *never* go over 70-75C
(well, not for long) as enzymes in the wort, which are performing the
starch conversion of the grain, can de-nature and become useless for
the mash and render the brew unfermentable - not desirable! This limit
may be even lower (say 60C) at some stages for stepped mashing.
2). Heating and pumping/recirculating must stop when the temperature in
the mash tun (not the underback where we'll be heating the wort and
pumping from) is at the desired step temperature, say 66C

So thinking about it, an even more custom solution is required with not
one, but two temperature probes.

I was wondering - I have PIC microcontrollers 16F628A at home, with
necessary programming hardware and software development tools.

I could make something to perform a controlled level out to the heating
element, using the reference voltage generator of the 16F628A rather
than simply turning the heater on and off. Of course the problem here
is that I don't know how to scale up a 0-5v variable range to what's
required for the heater element running on mains voltage. i.e. do I
need to vary the current/resistance or the voltage peak-to-peak of the
heater element, I'm not sure how to achieve either.

Hmmm, maybe on/off is ok for the <= 70C part, but that still leaves me
wondering how to physically measure the temperature. I don't mind
making my own sensor out of stainless steel rod (somehow?) and
performing the calibration etc, and using a cct/PIC microcontroller to
act on the levels and perhaps drive an LCD display for the underback
and the mash tun.

>>From reading the FE33L manual, they suggest any probe will work as long
as it has a resistance < 30 ohms and that the shorter the wire, the
more accurate it will be. Any suggestions on making a probe form
stainless steel rod?

I take it a GFCI is different to an RCD? I was always planning on
using an RCD in the 240v cct.

Thanks once again,
Mark

.

Relevant Pages

  • Homebrew Digest #5425 (October 01, 2008)
    ... OCTOBER'S HOME BREW DIGEST BROUGHT TO YOU BY: ... Mash Temp and Color ... Subject: pH and temperature ... wort provided that your meter is ATC equipped as nearly all are these ...
    (rec.crafts.brewing)
  • Re: Still a few bugs in the system (very long)
    ... water, push connectors that were not supposed to leak. ... temperature of 120, which I maintained for 20 minutes. ... I had just read that if you don't mash out, ... I put the chiller in the boiling wort, waited a couple more minutes, ...
    (rec.crafts.brewing)
  • Still a few bugs in the system (very long)
    ... water, push connectors that were not supposed to leak. ... temperature of 120, which I maintained for 20 minutes. ... I had just read that if you don't mash out, ... I put the chiller in the boiling wort, waited a couple more minutes, ...
    (rec.crafts.brewing)
  • Re: Still a few bugs in the system (very long)
    ... fermentation temperature, I had a gallon of wort as a starter, ... water. ... I had just read that if you don't mash out, ...
    (rec.crafts.brewing)
  • Re: OT: SETI Shutdown
    ... >>keeping a room at constant temperature and heating it up every time from ... house at constant temperature. ... It's all about the balance between cost and comfort. ...
    (uk.media.tv.misc)
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