PID Still Controllers
- Hello to everyone. I'm new to the newsgroup, but have been distilling
for quite a while.
I have seen a few queries regarding PID controllers and decided to
throw in my 2 cents worth.
I currently use a PID controller on my still. The guts of it is an
OMRON E5CW (The specs are available from here -
www.mikrokontrol.co.yu/pdf/tempcontrol.pdf). As with most of these
units, they provide a control voltage but you will need to build some
circuitry to get this to switch the power to yur heating elements.
I have an electronics background and have built my own controllers in
the past but would recommend against it as you can't compete with the
functionality of a unit like the E5CW. It cost me about AU$400 with
the additional circuitry another AU$100.
Why should you bother?
As you probably all know, the boiling point of an ethanol/water
solution is predetermined. The % of ethanol in the vapour produced is
also predetermined (by the temperature at that point). If you can
hold the temperature at the top of your column fixed, you will get a
consistent % of ethanol produced throughout the entire distillation
The narrower the temperature range, the less opportunity there is for
other compounds to come across with the ethanol. The still is the
best place to be removing undesirables.
While it is possible to distil a 5% wash with the output temperature
set to 78 degrees in practise its so damn slow that it isn't worth
A better method is to do an initial distillation (without removing
the heads and tails). Redistil the output, with the temp at the top
of the tower set to 76 degrees, venting anything that comes across.
Once that stops, set the output to 78. The entire process is carried
out at 78, making the output very pure. When the alcohol has all gone
the set temperature is too low for anything else to come across so
the still just sits there simmering (the controller hunts a little,
and it uses electricity, but does little else until I shut it off).
I have a 125 litre still and ferment in a 200 litre barrel. Using my
still controller I am able to leave the still unattended.
Apart from the OMRON controller all the other bits and pieces were
purchased from Dick Smith Electronics. I would be happy to supply the
circuit details to anyone who knows enough to not electrocute