Lighthouse Controller
Kit Construction
revise 05-03-10

(Click here to view the article on the lighthouse)

The first step in constructing the lighthouse controller kit uses the parts in this photo.  The parts include:

• Red/Black power cable (connect to source of 6-12 volts DC)

• circuit board

• filter capacitor (note pin marked as positive)

• 2 pin and 3 pin headers

• 7805 voltage regulator

• 10K resistor (brown/black/orange)

• 22K resistor (red/red/orange)

• 470 resistor (yellow/violet/brown) - (x2 - only one shown)

• 1K resistor (brown/black/red)

• TIP101 Darlington transistor

• diode (note silver band at one end)

• 8 pin IC socket

• PICAXE 08M processor

• red or green power LED

• 5mm white LED

• The Halogen Bulb kit includes a 10 watt Halogen bulb (not pictured)

CAUTION: Please do not apply power to the circuit board before reaching the point in the instructions where you are directed to do so.  Also, do not insert the PICAXE processor until asked to.  Even though it is shown inserted in some of these photos it should NOT be inserted until the board is completed.

1. Place and solder the IC socket.  Note that the notch in the socket is at the top.  Be careful when placing the 8 pin socket as the circuit board supports either an 8 or a 14 pin socket.  The 8 pin socket goes all the way at one end as shown in the photo.
   

2. Insert and solder the filter capacitor - note that the "+" on the board must match up with the "+" on the capacitor.  The "+" lead is usually longer, too.  In the photo the black side (unprinted side) is away from the 7805.

3. Insert and solder the 3 pin 7805 voltage regulator.  Note its orientation in the photo.
   

4. Insert and solder the 10 K resistor (black/brown/orange) and the 22 K resistor (red/red/orange) as shown.  The direction of insertion is not important as resistors can be inserted either way.
   

5. Insert and solder the 470 ohm (yellow/violet/brown) resistor

6. Insert and solder the red or green power LED.  Its longer lead goes into the "+" hole and the side with the flat area is negative.

7. Trim all leads flush with the bottom of the board.

8. Solder a red wire to the positive power connection and a black wire to the negative connection as show. 

9. Insert and solder the 3 pin header by the 10 K and 22 K resistors.

To protect the circuit from an incorrect connection to power (reversed polarity) a trace needs to be cut on top of the board and a diode needs to be soldered to the bottom of the board.  The orientation of the diode must be as shown, with the silver band towards the voltage regulator.

The cut trace is shown here, just above the red wire.  Make  sure that the trace is completely cut..

Insert the 1 K (black/brown/red) resistor as shown here.  Solder and clip its leads.

Insert the TIP101 Darlington transistor as shown.  Solder and clip its leads.

Insert the 470 ohm resistor (yellow/violet/brown) and the LED.  The longer (anode) lead  of the LED goes to plus.   You may want to extend the LED's leads with longer wires so that the LED can be placed off of the board.

Here is the completed board. 

... and the bottom of the board.  Check for solder bridges and poor solder joints.

Here is another view of the top of the board.

Make sure that all components are properly mounted and that the PICAXE is NOT installed.  Connect power to the red and black wires.  MAKE SURE YOU OBSERVE PROPER POLARITY or the unit will not work.  Red to positive power and black to negative.

The green or red power LED should light brightly.  If it does not DISCONNECT IMMEDIATELY and check for bad solder joints, reversed components or solder bridges.

Once the LED lights properly insert the PICAXE chip with the notch oriented as shown.  Make sure the label is as shown.  You will also note a small indentation on the left side of the chip.  This denotes the end with pin 1 and must be to the left as shown above.  Be careful to insert the pins directly into the socket.  You may need to bend them in a bit to get them to fit properly.  If you are not sure if they went in properly gently pry the chip out with a small screwdriver and try again.

Halogen Bulb Option

If you are using the Halogen bulb it connects to the two pins just below the TIP101 that are marked "bulb".  You can also connect multiple LEDs to these terminals.  In order to properly illuminate the Halogen bulb you must supply 10-12 volts DC to the power pins.  Do not exceed 12 or 13 volts or the bulb may have a significantly shortened life.

If you are using one or more LEDs with the unit the construction is the same as for the Halogen bulb.  The LED must have an appropriate current limiting resistor wired in series with one of its leads.  I routinely cut the positive (longer) lead and insert the resistor there.  Here the cable that connects to the board has been soldered to the LED's negative lead (white wire) and the positive lead (red wire) - note the current limiting resistor.  In this example the resistor is 200 ohms.

PICAXE Software (from article)

Diode Protection Modification

In order to protect the board from incorrectly applied polarity a minor modification can be made. 

First cut the trace that goes between the positive DC Power connection and the voltage regulator.  The trace to cut can be seen clearly in the pghoto below at the very end of the screwdriver tip.  This trace was cut with a small Dremel drill bit.  You can also use a utility knife.  Once it has been cut apply power and confirm that the board is not working by observing the power LED - it should NOT light.

Next solder the small diode on the bottom of the board as shown below.  Note that the banded end of the diode MUST go towards the voltage regulator.

Carefully trim the diode's leads and check to make sure there are no shorts or solder bridges.

 Test by applying power.  The power LED should work when the power is applied correctly.  It should not light but no harm will be done if it is BRIEFLY connected backwards.

Time adjustment modification

The time between flashes is normally adjusted in software.  This modification makes it adjustable by means of a small potentiometer.  This modification requires some rewiring of the board.

The potentiometer is the white object on the right.  Turn it full left for 0 pause between flashes and full right for 25 seconds.

This photo shows the proper orientation for the power (red / black wires) and LED (red / white) wires.

Here are the modifications that were made to the bottom of the board.

Here are the four LEDs wired in series.

These photos show another configuration of 4 @ 5mm LEDs that will fit inside of a 1" tube with a space in the middle to allow an insulated 8-32 bolt to pass through.

In this photo a modified unit drives two sets of LEDs which plug in on the right.  Note that the + and - (red / white) wires must be inserted as marked. 

Latest Board Revision

The potentiometer is the white object at bottom center.  Turn it with a small screwdriver.  Clockwise to increase delay, counter clockwise to decrease delay.

The power plug goes to the left.  Be sure to align the pins so that positive (red) goes as shown.  The bulb goes in at the right.  If using LEDs the positive lead (red) needs to go to the left as shown.  If using Halogen it does not matter.