Notes for construction:

We suggest you start by forming the resistor and diode leads first and then mounting and

soldering the ‘lowest’ components first.

Note that the tracks and pads on the PCB may have a protective clear lacquer which melts away

when soldered, so on these you will not need to clean the copper first. When soldering the

switch you will need to use quite a bit of heat to solder the legs properly but be careful not to

apply heat for too long. It is better to use a hotter iron for less time than a cool iron for longer!

The 555 timer integrated circuit is not especially static sensitive but should still be inserted last.

To protect the PCB pads you are strongly recommended NOT to fit and solder the coax cables

until you have constructed the wooden T support, aerials and mounted the metal case/tin.

Qty

Component Value

1

1K CR25 resistor (Brown Black Red Gold)

1

wire link (use one of the cut off resistor legs)

1

100K CR25 resistor (Brown Black Yellow Gold)

4

470R CR25 resistor (Yellow Violet Brown, Gold)

2

1N4148 / 1N916 equiv diodes (Note polarity line)

2

10nF capacitors (marked 103)

4

1nF capacitors (marked 102)

1

8 pin IC socket

1

2 Pole 3 position centre off toggle switch

1

PP3 Battery clip

1

NE555 Timer (fits into socket)

10nF

10nF

1nF

1nF

1nF

1nF

1k

Ω

100k

Ω

470

Ω

470

Ω

470

Ω

470

Ω

1N4148

1N4148

555 IC

1

wire link

Centre-off

DPDT toggle

Switch

Top (Component) View

Black

Red

Simple test

You may want to give your completed board a basic test before final assembly - if you have

access to an oscilloscope you can do this easily. After thoroughly checking all parts are located

and the battery clip is wired correctly connect a battery to the clips and an oscilliscope test probe

to pin 3 of the 555 IC and the ground lead of the scope probe to the Black/negative battery wire.

With the toggle switch in either the up or down position the scope should display a square wave

oscillation. The rest of the circuit is hard to test but as long as it has been assembled correctly it

should all work on completion

2

NARC DF100 PCB construction