Embedded Files
Wire size
Wire size selection is based on two factors. Current drawn through the wire and voltage insulation required. For most tasks inside a pinball cabinet, wire AWG25 or 0.5mm flexible wire is fine. It is good for approx. 3 amps and most of the stuff used in a pinball cabinet is well under 3 amps. For mains voltage wiring, 1.5 mm2 flex should be used. Because there will be some Mains Voltage cabling in your cabinet, the safest practice, (And law in Australia for electricians), is to have insulation on all wires to the highest rated voltage in the cabinet. So make sure the cable you are using for everything, even the stuff you’re using for 12 volts DC, is rated to a minimum of 230 V ac. You may find places cheaper where you are but try an electrical wholesaler for your wire. When it comes to choosing wire colours, I cannot emphasise enough to buy a few different colours and set yourself a code for what the wire is for.
For example –
Red – 12 Volt DC from power supply
Black – Ground from power supply
Brown – 240 AC from mains
Blue – Neutral AC from mains
Purple – Outputs from LEDwiz
Use as many colours as you want, but wiring your whole cabinet in one colour is asking for disaster and will make fault finding very difficult.
Fuses
Used primarily for stopping the magic smoke that makes everything electrical and electronic work, stay inside the components. There are a million different types of fuses and holders and it can be a bit daunting to the inexperienced on what to select. A quote from a Jaycar primer “Fuses are possibly the most misunderstood components in electronics, and often regarded as a nuisance. In fact they play a very important role as a safety valve in many circuits, protecting both the equipment from costly damage and the user from serious injury or possible loss of life.” For a pinball, I recommend either M205 or 3AG Glass fuses. They are cheap and easy to replace. As for holders, it is totally a personal preference. A quick Google search will show the different types available. Fuse size selection is to protect the cable from burning out or to stop a short circuit damaging components. I will go into more detail of fuse selection later.
12 Volt DC power supply
A lot of the components we are using in our cabinets are going to be 12 volt DC or 24 volt DC. This is for a lot of reasons that I am not going to delve into here, but because DC mains to the house went out a few years ago, we have to use a power supply to convert the incoming mains voltage from 230 Volt AC to 12 Volt DC. There are many types’ available and varying qualities. In my trade I have had to use a lot of brands and types and personally recommend the MEANWELL brand. They are reliable, have inbuilt short circuit, over current and thermal overload protection as well as good quality components. Either the DIN rail mount or the enclosed types are the best option. Once again, an electrical wholesaler is a good place to source these. The amperage size you will need will once again be dependent on what gear you will be running off it. If you only have a few LED’s and a couple of contactors, you will not need a massive power supply, but if you have a setup like Chriz99, you will need an appropriate size power supply to drive it all. You can never have too much power, but not enough will have all your bling turning off. Aside from a dedicated power supply, there is the option of using an old ATX power supply for the job. There are a few cautions that need to be heeded, but Gstav has given a link and a few points on what to watch for.
Terminals
There is going to be a lot of gear powered from the power supply, and 40 wires jammed into one terminal might work for a little while, eventually it will fail. The best way is to pick a distribution method for your wires.
FOR ALL MAINS WIRING, ENSURE THAT THE CONNECTION METHOD THAT YOU USE IS RATED FOR THE VOLTAGE AND CURRENT THAT YOU WILL BE USING.
The white terminal strip shown above is rated at 400 volts (ratings are based on maximum voltage that the insulation between two terminals will remain insulated from each other) but the tag strip above it obviously is not and would be dangerous to use at mains voltage as the terminals are exposed and could be unintentionally contacted. I personally will be using terminal strips in the bottom left image as it is what I am used to using but it again, comes back to personal preference. Control – Relays
Control – Relays
Relays are used when you need to control a large current load with a low current signal. A good article on relays and why they are used is here, but basically we are using relays in our pinball cabinets because the LEDwiz outputs are good for 500ma and some of our loads will be larger than that. If a large load is connected directly to the LEDwiz, it will let the magic smoke escape and give a great little pyrotechnics show.
I have used a LOT of relays at work and quite simply, Finder relays are the only way to go. The 95 series base and 44 series relay are great for the job with the great quality components and are available from Wolfsoft here or once again the electrical wholesaler
These units as pointed out by Chriz99 have diode module (pictured below) so while no extra diode is needed, I still recommend to put one on the contactors and gear motor. Relays have basically 3 specifications, coil voltage, internal contact amperage and the number of ‘poles’. We need a 12 volt DC coil (or 5 volt if you have a 5 volt power supply), and the contact amperage needs to be larger than the load we are connecting to it. Both the 55 series and the 95/44 series are good for about 10Amp at 250 Volts which should be more than enough for any load we are connecting. The number of poles refers to how many ‘internal switches’ the relay has.
Let there be Light – Cree LED’s
LED’s are almost needed for a DIY pinball project as much as the flipper buttons.
To do the Cree’s it will help to have some basic electronic skills and be able to wave a soldering iron around a little. An LED is a Light Emitting Diode that creates light when the specified voltage is across the anode and cathode with the correct polarity, but the current must be limited through the circuit or you will end up with a Non Light Emitting Diode or as they more commonly known, a Friode.
Once again in the words of Dan Rutter – “If you overdrive an LED brutally, it'll still end up as a friode, but it will in the interim briefly function as an SED, or Smoke Emitting Diode.”
With most things electronic, when electricity is changed from an electrical signal to another thing; light, motion, etc, some of the power is wasted as heat. LED’s, especially high powered ones like the Cree’s, have a problem of the hotter they get, the lower their resistance becomes, which in turn allows the LED to dissipate more power, which lowers their resistance and the cycle continues creating what is known as thermal runaway. The LED will become a SED pretty quick if this is not controlled.
A heat sink is needed for a Cree LED to dissipate the heat. There are many different types, here’s a link to the ones available from Wolfsoft and the ones I am using from Element14.
A series resistor is needed to control the current allowed to pass through the LED. To calculate the size resistor needed, you need to know a few things
Supply voltage
LED forward voltage
LED forward current
And this LED Calculator web site
Most of us will be using 12 Volts DC from our power supply and where you bought your Cree LED’s from should have a link to the datasheet for the other two details. For the Crees that I am using from Cutter electronics, the datasheet specifies that maximum forward current is 700 mA and forward voltage is; Red – 2.2 VDC, Green – 3.4 VDC and Blue - 3.2 VDC.
700 mA is too much for our LEDwiz which only allows 500 mA per output so we can reduce this to 450 mA forward current and use 5 Watt, 22 Ohm resistors.
If you want to drive you LEDs at their full 700 mA, you need to use either a relay or an optocoupler, but I will not be going into that here.
LEDwiz
So everyone is going to have a different set up so please ignore the precise numbering of where things are connected to the LEDwiz as this can be configured to suit your setup. This thread is a discussion of a LEDwiz default configuration and has some great info and utilities. I highly recommend reading the thread and seeing what is possible. I will be going with Chriz99 LEDwiz setup as below.
The numbers in the two shades of grey on the left are the LEDwiz terminal numbers and the two shades of grey represent the different grouped outputs.The details on the right are a long description of the output.
The LED wiz instructions are here.
In the instructions it states “The output drivers used with the LED-Wiz+GP™are technically capable of handling up to 50v at 500ma per output. However, as the LED-Wiz+GP is not designed to handle the maximums possible as a result of driving every output at its fullest potential, it is ultimately up to the user to decide what is and when deciding how to use the LED-Wiz in their application.”
So maximum 500 mA output per output but not all on at once. This is why Chriz99 configuration has spread all the different items across the LEDwiz so that no one driver is over loaded. If you are going to do a different configuration, total load on each bank needs to be considered. The driver chips can get hot so it’s recommended to put some heatsinks onto the chips (the four identical chips on the board)
Google Sites
Report abuse