Setting up the system.
Our soldering system will look like this:
But this is only a really basic setup. In the real one you should provide a correct earthing and some over-current protections.
Please don’t try to build this if you don’t have experience in electrical installations!!. Hacking a toaster oven for soldering involves playing with dangerous voltages that can cause death.
So lets begin:
- You should first take a look to your toaster oven. If the oven can reach temperatures well over 270ºC you don’t need to modify it. You just fix the thermostat to the maximum and leave it like this. If your oven can not be set to a temperature over 270ºC you will have to bypass the oven’s thermostat. So open it and bypass the thermostat so there is no regulation in the oven, take into account that from this moment the oven does not have any temperature regulation, it will just go up and up until it burns, the only security will be the controller, and this is not intended to be a safety interlock so make sure you supervise it and never leave the controller working alone and provide additional temperature measurements. Make this is at your own risk. If you modify the toaster oven’s internal cabling make sure that you don’t leave cables exposed to high temperatures, this could lead to burned cable isolation and electrocution risks.
- Now you should connect the Solid State Relay. One of the supply phases in the plug of the oven must be connected to the relay output and the other must be connected directly to the 230Vac power connection.
- After this my personal recommendation will be to connect between the relay and the power grid an MCB over-current protection and to a RCD (residual Current Dis-connector) if you personal installation is not already equipped with one. See the diagram below for details.
- Now lets connect our controller to the relay, in the diagram you can see the which terminals to use and the polarity. Remember the that the OFF/ON signal for the relay is 0/5Vdc so the choose a SSR should be compatible with that.
- Next would be to connect the K-type thermocouple to the controller. See in the photos for the terminals to use. For the polarity, normally red means positive but in some thermocouples you don’t have any indication. In this case just try, if the polarity is not correct when you heat up the TC the temperature measurement will decrease, so inverse the cables.
IMPORTANT: The controller card power supply is the usb 5V of your PC. Be carefull with that. Both your oven and your computer are earthed (or should be), and in most cases there is a connection between USB GND and earth in your PC so you need to make sure that the earth is the same and that you don’t connect two different earths potentials through the K-thermocouple or you will have currents flowing through the USB cables link. Please make sure your thermocouple is isolated from the oven earth to avoid this as it can mess up the temperature readings and in the worst case damage your PC.
- To connect the controller to the computer just use a standard USB cable with USB mini type B connector on the controller side.
- Before passing to the software setup make sure that your the earthing of your system is Ok. You must have continuity between the earth in the power plug and metal parts in the oven. Use continuity meter to check that, measure continuity between the oven metal exposed parts and the Earth in your mains connection point. This will assure that your RCD equipment will work as expected.
At this moment your hardware configuration should be ready, please make sure again that everything is well connected and isolated before going forward.
Before being able to communicate the controller and your computer you must install some drivers and utilities.
- Install the Microsoft Framework 3.5 sp1. http://www.microsoft.com/en-us/download/details.aspx?id=22
- Install Visual C++ 2008 redistributable.
- Install MSChart.exe for Framework 3.5 sp1. http://www.microsoft.com/en-us/download/details.aspx?id=14422
- Install N_electronics controller program. You can download it here.
- Plug the your controller on the computer using the USB cable. Let the drivers get installed.
- Run the controller program.
The links provided are only for 64 bits versions of your operating system. You can easily find in microsoft website the x86 versions.