Re: [APD] DIY jobs

["Mariano F. Bonfante" <mariano_bonfante at hotmail_com>]

Adding a rectifier is inexpensive and looks worthwhile as a prevention, but 
I have neither specific data of effects on fish and plants. The current 
through the system is 0.5 amp , which is not neglectable.

Controlling temperature to a precise point has it drawbacks IME. For 
example, in winter heater is on and water temperature is 25ºC. In summer 
water temperature is 29ºC, and heater is off.

Once I try with a switching bulb sensing temp close to the heaters, 
maintaining it constant. What I saw was too much heat in winter, no heating 
in summer, so constant adjustment was needed. Therefore, I prefer a constant 
differential temperature system instead, keeping the temperature difference 
instead of absolute values.

Mariano



>From: Nicolas Munro <nmunro at qld_yokogawa.com.au>
>Reply-To: aquatic plants digest <aquatic-plants at actwin_com>
>To: stuart at stuarthalliday_com,        aquatic plants digest 
><aquatic-plants at actwin_com>
>Subject: Re: [APD] DIY jobs
>Date: Wed, 07 Sep 2005 13:07:10 +1000
>
>Have you looked into this AC vs DC?   I would have thought/assumed (non
>researched) that the fish would be more affected by the AC signal as its
>always changing. EMF goes one way then back the other way, 50 or 60
>times a second??
>
>Either way do the fish just get use to it and accept the EMF / magnetics
>after a while?
>
>
>
>=Nick
>PS: use a diode in reverse direction and a opamp to measure the temp of
>the resistor, you should (with a fancy circuit) make it stable and self
>regulating to reduce the amount of current required.
>
>
>
>Stuart Halliday wrote:
>
> >Mariano F. Bonfante wrote:
> >
> >
> >>Local outlets has 220V 50Hz, so I am using a 60Vca (typical en CATV
> >>industry), galvanic insulation transformer for feeding the resistors. 
>There
> >>is also a dimmer circuit, to allow two phases: day and night. Daytime
> >>permits the substrate to be 1ºC above the water, nigh phase just a bias
> >>voltage.
> >>
> >>
> >
> >
> >
> >>I spent some time with these systems, but it is fun and I like it.
> >>
> >>
> >
> >Cute.
> >I'm a IT engineer, who was a electronic engineer, so I've often built my
> >own low powered heaters for small Aquariums.
> >
> >I put the resistors in a test tube and fed them 18V DC @ 1.1A from a
> >basic regulated off the shelf DC power supply.
> >So no risk of electric shock or it failing like normal heaters.
> >
> >It has as a side effect, a low electromagnetic field due to its use of
> >DC as oppose to using AC. Some say fish are sensitive to these fields.
> >
> >
> >
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