Ok, this is the big one, the most complex part of your Personal Particle Accelerator. You’ll want a couple of straight hours to spend on this.
Required Tools / consumables
- Fine tip soldering iron
- Needle nosed pliers
- Side cutters
- Fine tip flat screwdriver to adjust SMPS
- Fine tip phillips screwdriver for wire connections
- Fine solder
- 12V DC power supply
- Multimeter Hot air gun (/hair dryer)
These instructions cover the standard kit with 3 electromagnets and thus only requires 3 sets of supporting components (MOSFETS, transistors and resistors etc) – see photo below. If you’re building the Super size PPA, you’ll need to double the relevant components – see the Super Size PPA specific documentation.
Perform the soldering and assembly in the sequence below, which has been chosen to start with the lowest profile components first, working up to the larger components. This makes soldering easier if the board is placed on a flat surface while soldering.
The small circuit board within its own packed is the Switch Mode Power Supply (SMPS). Remove it and connect the input terminals to a 12V DC supply and your multimeter in voltage setting to the SMPS output. Adjust the SMPS’s small adjustment screw with a screwdriver until the output is 8.5V. Do not solder into the main PCB now. Note that the SMPS adjustment screw seems to take a lot of work to prepare – I have had to rotate 30 or more times in each direction to get the SMPS output voltage to start responding to the rotation. Please be patient and keep turning your screwdriver until you see a response.
Insert and solder the following components.
|R1||1M||Brown, black, green, gold.||Resistor to positive terminal of op amp configured as comparator|
|R3||390R||Orange, white, brown, gold.||Common Ground bar graph resistor|
|R4,R5||390R||Orange, white, brown, gold.||Bar graph indicator resistors|
|R8,R24,R25 (nearby LED bar)||3k3||Orange, orange, red, gold.||Resistors to bias Strobe transistors|
|R10||27k||Red, violet, orange, gold.||Resistor divider for comparison reference point|
|R11||40k2||Yellow, black, red, red, brown.||Resistor divider for comparison reference point|
|R2, R18, R19||300R||Orange, black, black, black, brown. OR Orange, black, brown, gold||Resistors to bias MOSFETs|
|R26||10k||Brown, black, black, red, brown.||Pull down resistor for enable switch|
|R6||10k||Brown, black, black, red, brown.||Pull up resistor as part of RC network during Arduino reset|
|R31||220k||Red, red, yellow, gold.||Input resistor to op amp configured as tacho|
|R32||10k||Brown, black, black, red, brown.||Feedback resistor in op amp configured as tacho|
|R9||220k||Red, red, yellow, gold. OR Red, red, black, orange, brown||Feedback resistor in op amp configured as tacho|
|R7||220k||Red, red, yellow, gold. OR Red, red, black, orange, brown||Resistor for positive input to op amp configured as tacho|
|R12||1M0||Brown, black, green, gold.||Input resistor to negative terminal of op amp configured as comparator|
|R15||510k||Green, brown, yellow, gold OR Green, brown, black, orange, brown||Resistor to reset op amp configured as latch|
|R27||10k||Brown, black, black, red, brown.||Resistor to reset op amp configured as latch|
|R16||1M0||Brown, black, black, yellow, brown. OR Brown, black, green, gold||Resistor for negative terminal of op amp configured as latch|
|R13||750k||Violet, green, yellow, gold. OR Violet, green, black, orange, brown||Input resistor to op amp configured as latch|
|R14||510k||Green, brown, yellow, gold OR Green, brown, black, orange, brown||Feedback resistor for op amp configured as latch|
|C1||2200uF||2200uF electrolytic capacitor||Note polarity. Bulk capacitor to support electromagnet operation|
|C2||0.1uF||104||Decouple caps for IC|
|C3||22uF||226 Tantalum cap||Note polarity is such that the positive end of the capacitor is towards the nearest edge of the board. Output cap for 7809 strobe LED supply|
|C4||2n2||222||Arduino reset timing capacitor|
|C5, C6||0.1uF||104||Time contstand for Tacho circuit|
|C7||0.1uF||104||Decouple caps for IC’s|
|C8||4u7||4.7uF electrolytic capacitor||Note polarity. Input Cap for 7805|
|C9||0.1uF||104||Output Cap for 7805|
|Q0-Q2||IRL2703||IRL2703 TO-220||Note polarity. Logic Level MOSFET|
|Q8, Q9, Q10||2N3904||2N3904 small transistor||Note polarity. BJT transistor for Strobes|
|D2||1N5408||1N5408||Protection against reverse polarity from 12V supply. Note polarity: solder with diode’s cathode (white ring) down towards the white ring on PCB|
|D3||1N4004||1N4004||Ensures the SMPS supplies the Arduino, not the other way around. Note polarity: solder with diode’s cathode (white ring) down towards white ring on PCB|
|4 pin header terminal||Solder to Power position|
|4 pin header terminal||Solder to Thrcon position|
|4 pin header terminal||Optional solder to Pump position|
|2 terminal screw connectors||N/A||Blue 2 pin connectors||Solder to positions X0, X1, X2 and the (12V GND). Screw terminal should face outward from PCB.|
It’s easy to get into the habit of trimming leads as you solder them. But whatever you do, don’t trim these leads!
|6 pin and 8 pin black sockets for Arduino||N/A||6 pin and 8 pin black sockets for Arduino||Solder into ARD1 and ARD2 sockets !! Do not trim the leads, they are used to connect to the Arduino !!|
|14 pin IC socket for IC5||Black 14 pin IC socket||Solder to position, with orientation mark as per silk screen|
|16 pin IC sockets for IC1 and IC3||Black 16 pin IC socket||Solder to position, with orientation mark as per silk screen|
|20 pin IC socket for BAR1||Black 20 pin IC socket||Solder to position, with orientation mark towards pin 1 noted on Silkscreen|
STOP ! Before proceeding, did you complete the procedure to set the SMPS voltage to 8.5V ? Voltage should be set prior to soldering. SMPS Daughter board to supply Arduino and 5V regulator. Note polarity. Position SMPS on long edge, with negative (-) terminals downward to PCB, soldered into pads centremost on the board. The screw should face outwards from the PCB. Solder short insulated jumpers from positive terminals of SMPS to nearby pads towards edge of the PCB.
|Power Supply Module||SMPS Daughter board to supply Arduino and 5V regulator. Note polarity. Position SMPS on long edge, with negative (-) terminals downward to PCB, soldered into pads centremost on the board. The screw should face outwards from the PCB. Solder short insulated jumpers from positive terminals of SMPS to nearby pads towards edge of the PCB. Solder thick leftover component leads between the SMPS’s negative terminals and the main PCB.|
|IC2||7805||7805 Note polarity. 5V regulator for TTL chips|
|7809||7809||7809 Note polarity. 9V regulator for Strobe LEDs|
|Dupont wire for enable switch||Solder two conductor cable with Dupont sockets to P19 and P20|
|Switch|| Plug the Dupont connector sockets onto the centre switch pin and either side pin (doesn’t matter which one). If the connections are loose, apply a drop of super glue across the black plastic Dupont connector and the red switch casing.|
The switch toggles the Enable pin of the output of the 74HC238 decoder used for the Electromagnets. This switch is useful to temporarily disable the electromagnets without powering down the PPA.
Half way point testing
If you’re using a laboratory power supply with inbuilt current display, set up Supply 12V DC to the power connector with indicated polarity.
If your power supply doesn’t have an in built current display, wire your multimeter in current measuring mode and wire in series with your power source.
Confirm current draw is under 20ma, indicating the SMPS is active but unloaded. If current draw is larger than this, quickly de-power and review your work for error.
Integrated Circuit installation
Now insert the IC’s and LED Bar Graph
|IC1||74HC238||74HC238||Decoder for Strobes Note polarity: chip orientation must match the pcb silkscreen|
|IC5||LM3900||LM3900||Norton Op amp for Protection Note polarity: chip orientation must match the pcb silkscreen|
|IC3||74HC238||74HC238||Decoder for MOSFETS Note polarity: chip orientation must match the pcb silkscreen|
BAR1 DC10SURKWA Common Ground bar graph. Note polarity: chamfered corner is pin 1, shown in top left of above photo.
Install two of the 25mm M3 screws from the Nuts and Bolts bag through the PCB’s two holes, and secure with an M3 nut each side of the PCB. The screws will act as stand-offs to lift the non-Arduino side of the board.
The strobe LEDs flash from the same triggers that drive the electromagnets. The strobes consist of the aluminium light pipe, LED and resistor. The light pipe reflects the LED’s light and abuts the PPA’s main tube at the angle of total internal reflection, to encourage the strobe’s light to travel down the tube.
- Identify the grey two-conductor cable from the Wires bag. For the Standard PPA, cut three equal lengths around 33cm each. For the Super PPA, cut into six lengths of around 50cm. The wire specs are listed further below.
- At one end of each length of wire, separate the two conductors 50mm, and cut short the black striped wire by 10mm
- Strip and tin each wire conductor at both ends
- Cut the LED leads to 5mm
- Solder the small 100R resistors (brown, black, black, gold ) to the LED cathode (with flat side on LED body)
- Solder the other end of the 100R resistor to the shorter lead with black stripe
- Solder the LED anode (non-flat side) to the longer grey conductor.
- Trim the supplied heatshrink from the lightpipe packet in thirds.
- Insert the LED into the flat end of the lightpipe as far as it will go.
- Slide one of the heatshrink pieces over the aluminium tube so half of it is over the aluminium tube and the other half over the LED leads. Apply hot air with hairdryer to shrink the heatshrink. This will secure the LED in place
- Repeat the above steps with the other two strobes
- Solder the other end of black-striped wires to P7/P8/P9 on Output board PCB
- Solder the other end of non-black striped wires to P13/P14/P15 on Output board PCB
Wire specifications: the wire provided in the kit was https://www.jaycar.com.au/light-duty-fig-8-speaker-cable-sold-per-metre/p/WB1702 . See the link’s specifications tab for full details.
Note that the strobes’ very low duty cycle means that almost any wire can be used.