7/32 Rat Tail File (Used for Sharpening Chain Saw Blades)

/ Constructing A Sidereal Day Scope

Materials

Qty. / Materials / Part Number
1 / 60/600 mm Mailing Tube
1 / Battery Holder Snap 9V (purchased as a pkt of 5) / S6100
1 / Battery Holder 2 x “AA” Cell / S6112
1 / LED 5 mm Circular Green / Z4087
1 / Mini Toggle Switch 250V AC & 2A / P7654
1 / Header Pin & Plug 2-Way / P2731
1 / 2.0 metre Wire Hook-Up 10 x 0.12 mm Red / W2220
1 / 2.0 metre Wire Hook-Up 10 x 0.12 mm Black / W2221
1 / Heatshrink Tube 1.2 m x 1.5 mm Black / W4100
2 / AA Alkaline Batteries
1 / Perspex Square 3 mm x 60 mm x 60 mm

Equipment

• Hot-glue gun

• Soldering iron

• Craft knife

• 7/32” Rat Tail File (Used for sharpening chain saw blades)

• Steel ruler

• Scribing tool / Compass

• Packing tape

• Black paint

• Wire cutting pliers

Safety

When using a soldering iron:

• Work in a well-ventilated area to avoid any fumes.

• Ensure that the hot tip of the iron is kept well away from the iron’s electrical cord.

• Take care not to burn your fingers.

When using a craft knife try to make small repeated rather than one large forceful cut. This reduces the risk of the knife slipping and cutting your finger(s). When you are not using the knife put its cap back on.

Never use your sidereal scope to look at the Sun.

Method – Constructing The Sidereal Scope

Step 1

Without removing the masks from the Perspex that protect it use a pair of soft jaws to clamp the Perspex square into a vice. Use the rat-trail file to file a groove into the middle of one side of the square. The groove needs to be deep enough for the LED to fit into as shown in Figure 1a.

Step 2

Remove one side of the mask from the Perspex. With the aid of a steel ruler and the scribing tool carefully etch a thin horizontal line across the Perspex square as shown in Figure 1b.

The best results will be achieved by making several firm passes along the same line rather than one heavy pass.

Figure 1a /
Figure 1b

Step 3

Remove the second mask from the Perspex. Use the hot-glue gun to glue the LED into position as shown in Figure 2a.

Step 4

Once the glue has cooled use some black paint to paint over the side of the LED that will face into the tube as shown in Figure 2b. The side that will face into the tube is the one that has the etched line on it.

Figure 2a /
Figure 2b

Step 5

Use the craft knife to carefully cut out the inner circle from one of the Mailing Tube’s end caps as shown in Figures 3a and 3b. You will also need to clip out a 1.0 cm gap from the lip of the cap as shown in Figure 3b. This is where the LED will sit.

Figure 3a /
Figure 3b

Step 6

Use the hot-glue gun to fix the Perspex square to the end cap as shown in Figure 4a. Remember that the side of the Perspex with the etched line needs to face into the tube. Trim the LED leads so that they are 1.5 cm in length. Remember to keep the long lead as the longest after trimming.

Figure 4a /
Figure 4b

Step 7

Using a pin or compass point carefully pierce an eyehole into the centre of the other end cap as shown in Figure 4b. To avoid any errors due to parallax whilst you are using the scope make sure that the hole is no larger than 1.5 mm in diameter.

Method – Making The LED’s Electronic Circuit

Figure 5 shows the circuit that needs to be constructed in order to power the Sidereal Scope’s LED.

Figure 5

Step 8

Solder one end of the 9V battery holder snap to a 100 cm length of wire hook-up. Remember to use some heat shrink to cover the exposed join.

Step 9

Solder the other end of the 100 cm wire hook-up to one of the pins for the 2-way header plug as shown in Figure 6a. Now solder one end of a 135 cm length of wire hook up to the other pin that will clip into the 2-way header plug. The pins of the LED will then slide into the header plug as shown in Figure 6b.

Figure 6a /

Figure 6b

Step 10

Solder the other end of the 135 cm wire hook-up to the middle pin of the mini toggle switch. Remember to put some heat shrink onto the wire before you solder then use it to cover the exposed join. Take a 55 cm length of wire hook up and solder one end to one of the end pins of the mini toggle switch. It doesn’t matter which one. Cover the join with heat shrink. See Figure 7a.

Step 11

Solder the remaining end to the other end of the 9V battery holder snap. Remember to put some heat shrink onto the wire before you solder then use it to cover the exposed join. See Figure 7b.

Figure 7a / Figure 7b

Method – Assembling The Sidereal Scope

Step 12

Insert 2 x 1.5 Volt batteries into the battery holder and then clip it to the rest of the circuit. Attach the completed circuit to the Sidereal Scope’s cardboard tube with packing tape. The battery pack should be placed so that it is close to the middle of the tube. See Figures 8a and 8b.

Figure 8a / Figure 8b

Figure 8a shows a sidereal scope that has been set up by taping it to a pole. The tape has been applied somewhat enthusiastically!

Figure 8b shows a sidereal scope that has been mounted to a tripod.

For teachers

Materials, parts and costing list – all electronic parts were purchased at Dick Smith.

Qty. / Materials / Part Number / Cost
1 / 60/600 mm Mailing Tube / $2.45
1 / Battery Holder Snap 9V (purchased as a pkt of 5) / S6100 / $2.28 ($0.47)
1 / Battery Holder 2 x “AA” Cell / S6112 / $1.67
1 / LED 5 mm Circular Green / Z4087 / $0.25
1 / Mini Toggle Switch 250V AC & 2A / P7654 / $2.29
1 / Header Pin & Plug 2-Way / P2731 / $0.58
1 / 2.0 metre Wire Hook-Up 10 x 0.12 mm Red / W2220 / $0.50
1 / 2.0 metre Wire Hook-Up 10 x 0.12 mm Black / W2221 / $0.50
1 / Heatshrink Tube 1.2 m x 1.5 mm Black / W4100 / $3.77
2 / AA Alkaline Batteries* / $1.60
1 / Perspex Square 3 x 60 x 60 mm** / $0.22

The heatshrink tube is used to cover the soldered joins between wires.

*The cost for the batteries will depend on the quantities in which you buy them. The listed price was based on $15.99 for a pack of 20 from Coles on January 17th 2008.

**Perspex sheet can be purchased from Bunnings Hardware in the following sizes:

600 x 1200 x 3 mm for $43.12 or

900 x 1200 x 3 mm for $69.49

You should be able to get 200 squares from a 600 x 1200 x 3 mm sheet!

This gives a unit cost of $0.22. The listed prices were obtained on January 17th 2008.

An approximate cost for making 1 sidereal scope would be: $10.60.