Adding an LED, buzzer or toggle switch to your auto top-off system
Important notes: to add aquahub's
you must use a 12V Wall Transformer in your system. A 9V battery
cannot handle these and battery life will be unacceptable. See
How to build your own aquarium auto top-off system for instructions
on converting from 9V battery to
transformer power. Also, you must
have a DPDT
Relay. Relays purchased at aquahub prior to March 1,
2006 are SPDT and do not allow for addition of LEDs or buzzers as
PLEASE NOTE: The following text describes a
do-it-yourself project involving household 120 volt electricity, which,
if mishandled, can cause shock or death by electrocution. Do not
attempt this project if you are not comfortable working with
electricity. Proceed with this project at your own risk.
Follow these steps carefully to add an LED to your
auto top-off system. The LED will light up when your system turns
the reservoir pump on, alerting you to system operation. Note:
the directions below describe the process for installing an LED with a
built-in resistor. A regular LED without a resistor cannot
withstand the voltage from the transformer. We no longer stock
1. UNPLUG YOUR SYSTEM FROM THE WALL!
How to build your own aquarium auto top-off system in its entirety before attempting this add-on.
3. Your float switch circuit (the two float switches
wired in tandem) connect to one transformer wire. Make sure that
these connect to the solid (not white striped) transformer wire and add
the blue wire from the LED into this connection by twisting it into the
connection (strip the end first). Add or replace the wire cap. See
the photo below.
4. Securely crimp a
clip to the red
lead of the LED and connect to post 3 of your relay.
5. Strip at least 1" off the end of the white striped
wire from the 12V transformer. Carefully divide the copper strands
and twist each to divide the power that will come from the transformer
into two separate bare wires. Attach quick connect clips to each
of these. Be sure to bend the strands over themselves a couple
times to create a thickness that can be securely crimped into the quick
connect clips. Connect one clip to post 5 of the relay and the
other to post 7, as shown in the photo below.
Posts 4 and 6 of the relay turn on the reservoir pump
by completing the 120V circuit from your extension cord when the float
switches complete the 9V power circuit to the relay coil (thus turning
the relay on). Similarly, we are now using the other side of the
relay - posts 3 and 5 to complete a 12V circuit through the LED when the
relay coil is powered. We are simply using the 12V power from the
transformer to power both the relay coil and the LED (that's why we
divided the strand from the white striped wire in two).
6. Re-insulate the relay connections with heat shrink
or a project box before plugging the transformer or extension cord back
into the wall.