1. Soldering PCBs – Siren Kit Week 2 of 2
Nick Carter
May

2. Activity Plans Soldering a Siren Kit (Elenco SP-1)
Week Make a European Police Siren PCB – part 1
Learn Soldering on PCB Breadboard (This is a custom breadboarding kit)
Learn how and practice
Learn to solder wires in PCB
Get parts kit and look at it
Learn about soldering Resistors and Capacitors and solder some
Solder Resistors (11), Capacitors (6) and wire jumpers (2), Potentiometer (1)
Week Make a European Police Siren PCB – part 2
Complete Resistor and Capacitor component soldering – and links (if not done)
Learn about Semiconductors soldering and solder them
Solder Transistors (2), LEDs (2), Integrated Circuit (1)
Learn how the circuit works at high level
Solder Speaker and Battery
Test the Circuit
Learn Unsoldering
Change 2 resistors to change the Tone
Troubleshoot & fix if necessary.

3. Introduction to Soldering (PCB Bread boards)
Peeuuu!
Cool
HOT
Nick Carter 4/21/2016

4. ONLY TOUCH or HOLD THIS PART
Safety Rules
ALWAYS wear SAFETY GOGGLES
Soldering Iron CAN BURN YOU BADLY
Soldering iron CAN BURN YOUR CLOTHES
Soldering iron - in the HAND or in the STAND
PUT it back in the STAND when not soldering
Cool
HOT
VERY HOT MELTS METAL
ONLY TOUCH or HOLD THIS PART
Hot like boiling water
OW!
OW!

5. Solder and the Joint
Solder is a metal mixture, mostly tin, that melts at 400 deg F (like your kitchen oven on MAX.)
Parts connected by solder are JOINED together. It is Solder joint. They are joined in 2 ways:
Solder makes a MECHANICAL CONNECTION fastening parts together – used for copper water pipes and electrical circuits
Solder makes an ELECTRICAL CONNECTION between the parts – used for electrical circuits
To make a good joint, the solder needs to stick to the parts (wet the parts). Wetting is also called “tinning”. It is good to have parts tinned and silvery before soldering.
The iron tip needs to be hot, clean and silvery
The parts need to be clean so solder will stick to them
The parts need to be hot before applying solder
Solder contains a chemical – FLUX - that cleans the parts.
It makes the smoke you will see. Do not breath this  Peeuuu!

6. Soldering is Joining Things Together We make a solder joint like this
Mechanically join the parts or hold them together.
They should not move while solder cools.
Heat both parts with the soldering iron.
3 to 5 seconds depending on size of wires
Too much heat can damage components
If the component has more than 2 leads, after 1, go solder a different component and come back so that the component does not overheat
Poke the solder wire onto the hot joint and it will melt and wet the parts we want to join
Add solder wire until parts are wetted and holes are filled.
Take the iron and solder wire off the parts so they can cool (Solder first, or it may stick to the joint)
Let the parts cool before moving them.
A good solder joint will be shiny. If it looks grainy, melt it and let it cool again.

7. Soldering PCB – Looks Like This
Cool
HOT
3. Push Solder into joint
1. Heat both parts with Iron
2. Wait until parts are hot (3-5 seconds)
4. Solder wets both parts
5. Take away solder and iron and let joint cool
OOPS Note:
If you take away the iron before the solder, the solder may stick to the joint.
If this happens put the iron on again to melt it and take away the solder.

8. Week 2 Soldering a Siren Kit (Elenco SP-1)
May Make a European Police Siren PCB – part 2
Complete Resistor and Capacitor component soldering – and links (if not done)
Learn about Semiconductors soldering and solder them
Solder Transistors (2), LEDs (2), Integrated Circuit (1)
Learn how the circuit works at high level
Solder Potentiometer (volume control) Speaker and Battery
Test the Circuit
Learn Unsoldering
Change 2 resistors (R4, R6) to change the Tone
Troubleshoot & fix if necessary.

9. Semiconductors and Heat
Semiconductors are easily damaged by heat
How do they get hot?
When circuits are not powered on
Soldering into circuits
High temperatures around them
When circuits are powered on by current flow
Passing currents higher than designed
Bad design not accounting for heat in operation
To keep Semiconductors working properly, all these ways of heating should be avoided as much as possible

10. Keeping Semiconductors Cool
When Soldering
Use a heat drain – drains heat from the wire before it gets to the component
Solder each wire quickly and let the component cool down between wires – we will do this
When powered on
Design the circuit so it cannot pass too much current
Add Current limiting components
Turn the circuit off if too much current
Cool the component
Heat sink – fins, fan, liquid cooling
Conduct heat into the board through its wires – the board is the heat sink

11. Inserting the Transistors and LEDs DO NOT FORCE THEM CLOSE TO BOARD
Transistor - Bend the middle lead away from the other two so that the 3 leads match the hole pattern in the board.
LED - match the flat on the diode to the flat on the board circle. Flat is by the shorter LED lead.
FLAT + _ L S
FLAT
Mount flush ONLY if you don’t have to force them in

12. At the
Clock
for30sec

13. At the
Clock
for30sec

14. ALL
SIX
LEADS

15. Insert and Solder the Volume Control
The kit calls this VR1 – Variable Resistor 1
Fit leads through the holes and solder it tight against the board A W B

16. Solder in Integrated Circuit (IC) Socket The traces are small, watch for solder bridges Insert socket same way as IC pin 1 (notch)
The kit has you solder the IC in directly. But we are going to use a socket.
The Socket has advantages
Cannot overheat the IC while installing
Can remove the IC if it fails
Can remove the IC if you want to reuse it
To insert the IC easily, first bend the pins by pushing the IC against the tabletop
PIN 1
Notch

17. Bending IC Leads to fit in socket
Push IC leads against table top,
flip IC over and do same for
leads on other side.
They end up straight
up and down.
Picture credit

18. Wire the Battery Snap to the Board
RED wire goes into + hole
BLACK wire goes into – hole
Solder wires into board.

19. Wire the Speaker to the Board
Cut 2 pieces of wire 6 inches
Strip 1/8 inch insulation from each end.
Insert wires through hole from back of board then into 2 holes and solder them.
Solder other ends of wire to speaker (either way around)
Fill the hole around the wire with solder

20. Connect the Battery 
If all is well, lights will flash and siren will sound
But wait…….is that the right sound?

21. Making the Siren Sound Right
Well they tricked us…..
They gave us wrong values for R4 and R6
They gave us what value?
We need to install R4A and R6A
Which is what value?
Oh. The “A” values are bigger.
How will this change the sound?

22. Removing R4 and R6 Remove the solder by
Using the braid or
Using a solder sucker
If the resistor wires are not loose after you remove the solder
Use a pair of pliers to wiggle the resistor wire from the back of the board until it is loose and the resistor comes out
If you cannot loosen it up with pliers
Cut the resistor wires on the top side of the board.
Pull the wire out with pliers while heating the solder pad.
Clean the solder out and make sure the hole is open

23. Install R4A, R6A, What do you hear?
Makes the 1 second timing period
Makes the Sound Tones 1 2 X X 2 1
Voltage change through R8 changes the Siren pitch when the lights flash

24. The Q1 and Q2 Oscillator
The Q1 and Q2 circuit is called an “Astable Multivibrator oscillator.
“Astable “ means Not Stable – it won’t stay where you put it.
Q1 and Q2 act as switches, controlled by the voltage between base and emitter. They turn on if that voltage is more than abut 0.6 Volts.
When one switches on (e.g. Q1), current suddenly flows in R2 and changes the voltage on the Q1 collector from 9V to about 2 volts. This voltage change zips right through the capacitor C2 and turns off Q2. Q2 collector goes to almost Batt+ voltage. Q2 collector voltage change zips through C1 and Q1 turns on even more.
The base of Q2 gradually comes positive as C1 charges back up through R4. When it is positive enough, Q2 switches on and current flows suddenly in (R1 & R7). This voltage change zips through C1 and turns off Q1. Q1 collector goes to 9V and turns on Q1 harder.
The base of Q1 now gradually comes positive as C2 charges back up through R6. When it is positive enough, Q1 switches on and current flows suddenly in R2. This voltage change zips through C1 and turns off Q1. Q1 collector goes to 9V and Q1 turns on harder.
They continue turning on and off alternately like this at a rate determined by how long it takes to charge up C1 and C2 with resistors R4 and R6.
For more detail see -

25. Voltages on Q1 and Q2 Voltages on Q1 are similar to this
Voltages on Q2 are similar but 1/2 cycle later
Q1 Collector Voltage
Q1 Base
Voltage
Capacitor C1 charging up
through R6
Q2 Collector Voltage
Q2 Base
Voltage
Same time on
both pictures
1 cycle
Capacitor C2 charging up
through R4
A “cycle is one complete repeat of the waveform.

26. Just for fun - This is “Pepper”
Pepper is a robot designed for human interaction by Softbank/Aldebaran company.
Programmers can use its cameras and processing to recognize speech and faces and to make it follow faces and people around with its eyes and gestures.
It is programmed with a graphic tool like the NXT robots programming tool, where you make a connected flow of actions and decisions and branches for different actions.
This robot is used in several stores in Japan and Europe and has significantly increased customer visits.
It is also used for applications like taking surveys or when people are more comfortable talking to a robot than another human.