Backyard Aquaponics
A place to discuss aquaponics

Also, WTF does "be link programmed" mean?

Kuda...

It's all about "programmable specitivity"....ask Kev... now I know where he got it from...

Low Cost Programmable Interval Timer

Ref: Silicon Chip Magazine June 2008
Here's a new and completely updated version of a very popular project: an easily programmed low cost electronic timer. It operates from 12VDC, with low current drain: <50mA when relay is on, <5mA when relay is off. It is link programmed for either a single ON timing period, or continuous ON/OFF cycling and can be link programmed for any of 48 different time periods, separately for ON time and OFF time. Selectable periods are 1/2/3/4/5/6/7/8/10/20/30/40/50/60/70/80 seconds, minutes and hours. It may be restarted at any time simply by pressing reset pushbutton. Kit includes PCB and all specified electronic components.

Parts List:
One solid-state relay (you choose the amperage to suit, I used 18 Amp / 120V, (US$6.50 used).
Others available like it at allelectronics.com

A DC power supply (anything from 5 to 9V DC is fine, from an old
"DiskMan").

One power-strip.

One "Bread Board" (We will build our little circuit on this, US $3 or less).

Four chips, some jumper wires of various lengths, a couple capacitors, and some
resistors.

Two wires approx 1’ (use some cord from the DC power supply mentioned above).

you won't believe they charge US$90 for these in many Grow shops!

Note that EXACT product codes are not important in selecting circuit parts. But, what IS important is for the numeric part of the code to match mine and for the number of pins to be the same. For example, if you found a 16PIN "TC4013BP" that would be fine even though the one I have says "TC4013BF". The capacitor can be any type, but if you get a polar one
like I did, make sure it goes in the proper direction. The resistors don't
matter so much, just get the res values correct. If you cant get a 130kohm resistor use a 100kohm and a 30kohm connected together, the same goes for the capacitors.


Setting up the breadboard
The Breadboard has two sides, which are electrically insulated from each other.We will call the left side GROUND and the right side POWER. We supply power and ground to the board by plugging our DC Power supply leads into bottom of the board (as shown). I recommend soldering these connections to pieces of (more rigid) jumper wire. You must match the positive wire from the power supply to the positive (right) side of the breadboard, and the negative lead to the left side. Usually, the positive wire will look different (e.g. have a white stripe like mine). The outermost holes on each side of the board are used to distribute power and ground (respectively) to an entire row of the board
The chips have either 8 or 16 pins each. The pins are numbered counter-clockwise (from bottom left of chip) as shown.

Building: You may connect the power and ground connections from the DC power supply anytime but DON’T PLUG IN BOARD DURING ASSEMBLY!

Note: When putting on the chips exact row positions don’t really
matter, just as long as the chips go in the order specified and are "down
the middle" of board, with lettering READABLE FROM THE GROUND SIDE.

Install all the chips

Chip#1 is the 555 timer chip.

Chip#2 = 4020B counter chip.

Chip#3 = another 4020B chip.

Chip#4 = 4013BF dual D-type Flip Flop.

Connecting the relay:
The Solid State relay has two ends, the DC control end, and the AC power end. ***Caution*** AC current can kill you, so please be careful. Make sure the power strip is UNPLUGGED.

We begin by slicing through the outer plastic of the Power Strip's insulation, about a foot or so from the plug. Peel back the insulation to reveal three wires (white, green, and black). The black one is the POWER wire, the one we will splice into the AC side of the relay. Cut the black wire and cut and peel back some insulation from each cut end. Make a small loop on each cut end, and screw down these loops under the relay's screws (AC end). [See picture for details]

Connect two small (8-12") pieces of wire [see parts list] to the Relay's DC
power and ground screws. Tape up the entire relay (especially the AC end) with black electrical tape (or duct tape). This will prevent any contact shorts and improve safety.

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To Set ON/OFF times:

Chip #3 controls OFF time.
Chip #2 controls ON time.

To change these times, simply plug the Yellow or Green wires into other pins (on Chips 2 and 3) as follows:

The following times are valid for chip 2 (ON time) and chip 3 (OFF time):

***Remember that the pins are numbered from 1-16 and arranged counter clockwise from bottom left of chip. Do not plug into any other pins besides those listed in table above!***


The board and relay could be fastened inside of a small plastic case with holes cut for the power strip cord ends. Make sure to keep components from touching though. Simply plug in your appliance into a spot on the power strip, plug in the strip and DC power supply, and set the ON/OFF times.

Here's the schematic of the completed cyclestat.

Be sure to add a filter capacitor as the schematic indicates to ensure proper timer functioning.

Below is the timer layout, featuring an "automatic on" function that restarts the timer in the ON position when power is applied. The resistance/capacitance values on the RC circuit are subject to what works. (The stated values worked for me, It's all about resetting the chips for long enough time intervals when power up occurs -- play around to find what works best for your timer.)

Shown Values:
Res. at bottom (added RC circuit) = 1K ohm
Res at middle = 10K ohm
Cap. at bottom (RC circuit) 68 uF.

-Don Piano

This can also be used to control co2. with This timer, a cheap thermostat ($20), dehumidistat ($30) and a couple of relays can substitute for a climate controller with co2 sequence control.

If you cant get a 130kohm resistor use a 100kohm and a 30kohm connected together, the same goes for the capacitors.

You lost me after So... !

oww....my head hurts......

to quote a country and western song

"I sometimes feel like roadkill on the information highway...."

All right. I know many people out there are interested in repeat cycle timers. I also know that to by a ready made repeat cycle timer is usually way over priced (between 60 and a few hundred dollars depending on type etc.)