This kit only requires the minimum of tools, these are:
- Soldering Iron
- Snipe-nosed pliers
- Side Cutters
- Wire strippers
Step 1 – Solder the Resistors
There are 3 resistors to solder. Start with R1 which is 1M and then fit R2 and R3 which are both 470R resistors. To solder them start by bending the wires using snipe noes pliers close to the body of the resistors as shown in picture. Note: use the pliers to take the mechanical strain when bending the wires and this should prevent them breaking close to the resistor body.
Fit the resistors flush to the board and bend the wires out slightly on the solder side to retain the resistors in place. You can then solder them in place either one at a time (easiest and recommended) or fit all three and solder them all at once (fastest for assembly).
Once soldered, trim the legs close to the board just above the soldered joint. Try not to cut into the joint as this will compromise the integrity of the joint.
Step 2 – Solder the diodes
There are 3 diodes to fit and it is very important to get them in the right places and not mix them up. They are not the same, even though they look the same!First fit D2 and D3 which are both BAT85 diodes.Secondly fit D4 which is a zener diode. Bend the wires and solder them using the same basic techniques that you used to solder the resistors in Step 1.
Step 3 – Solder the Capacitors
There are 2 capacitors to solder. Start with C1 which is 100uF and then fit C2.
[box type=”info”]NOTE: C3 is not fitted and is an option for later use[/box]
Step 4 – Solder the Sounder
The sounder is not polarised and so can be fitted either way around as shown. As always make sure that it sits flush to the board – apart from anything, it looks nice!
Step 5 – Solder the Microcontroller
IC1 is the only chip in this design and is the brains of the operation.
The first thing you need to do is bend the legs in a tiny bit, as it starts life a tad spread-eagled. The easiest way to do this is to hold the chip by it’s body and bend the legs on one side on a flat surface. They don’t need much bending, just enough to ease through the holes on the PCB.
Fit the chip into PCB so that it sits flush to the board. Take care to insert it the right way around – the notch should be towards the capacitors at the top of the board. Its a good idea to solder 2 legs of the chip first at opposite, diagonal ends of the chip. Turn the board over and make sure the chip is sitting flush. If not, dab the soldering iron onto the offending leg (on the underside of the board!), whilst pushing down on the chip with a finger from above. Take care not to touch the hot lead! Once the chip is flush, solder all the rest of the legs.
Step 6 – Solder the LED
The RGB LED is polarised and must be fitted the correct way around as per the diagram on the top silk of the PCB. If you get it wrong, its not the end of the world, its just that the red and green will be reversed.
Push the LED down as far as the shoulders on the leads which will make it sit 3-4mm proud of the PCB. It is important to mount the LED at this height, so that when the board is fitted to the Target plate it clears the rear face of the plate. Try and get the LED level so that when you look from the front the LED light shines nicely out from the centre of the board.
Step 7 – Solder the Switch
Turn the board over and fit the switch to the underside of the PCB as shown.
Step 8 – Solder the Battery Holder
[box type=”alert”]Important: Make sure the LED and IC have been fitted![/box]
It sounds obvious, but as the Battery Holder covers the LED and chip connections they must already have been fitted!
[box type=”alert”]Important: Make sure you fit the Battery Holder the correct way!![/box]
Fit the Battery holder the correct way around as shown on the underside of the board, if you get it the wrong way around then disaster will strike and you will “let the smoke out”. As everyone knows, circuit components are just fancy holders for special smoke. If you abuse them, then the smoke will start to escape…
Fit the holder as flush as you can to the board, so that it sits on top of the soldered LED and chip connections. If it isn’t as even as you’d like, feel free to trim the soldered connections that it sits on until it is.
Step 9 – Solder the piezo sensor
The piezo sensor is fitted to the connector as shown. It is polarised, so ideally try and get it the right way around, but if you don’t it’ll still work. For the best finish, cut the leads down a bit until they are about 3-4cm long and re-strip them. Connect the red lead to the + and the black lead to the – and solder.
That’s it you’ve done it! You’ve completed the electrical assembly!