Reflow oven: solid state relay box

Since no special electronics are inside the oven I built an electronic switch for the oven where the mains plug of the oven can be plugged in directly without the need to modify the oven. This also seemed a bit safer to me.

The solid state relay box is basically just a solid state relay inside a housing with on one side the mains part where power comes in and out and on the other side a DIN plug where the control signal comes in. This way all 'high' voltage stuff stays in this simple box and the controller can be completely low voltage.


First of all, some plugs and wires:
Power plugs and wire

A housing and aluminium plate that serves as both a base for the components and a small heatsink for the solid state relay (SSR). Not much of a heatsink is needed since the SSR is quite a heavy one.
Housing and aluminium plate

The SSR itself, capable of up to 25A but we only need around 3A (230V, 660W). The gray top is for additional isolation and can come off.
Solid state relay

Several kinds of connectors and strain reliefs for the mains power wires:

A ground wire from an old PC power supply, unfortunately not in the correct color, it should be green/yellow at least where I come from.
Groudwire from old PSU

Putting everything together

The strain reliefs go through one of the sides of the housing. These are Skintop Click-R strain reliefs that can be just clicked in and screwed tight.
Strain reliefs in side of housing

The DIN connector in the other side:
DIN plug in housing

Some holes were drilled in the aluminium base. The corners needed to be rounded a bit because the housing has some inconvenient pieces of plastic and would not fit otherwise.
Aluminium base

The mains part connected. Earth wires are connected through and also to the base (think of the brown ground wire as a green/yellow wire :). Crimp-on terminals were used everywhere because the wires were stranded. This is good for wires that need to bend but it is not a good idea to put stranded wire in connectors directly.
Mains wires

The wires go through the strain reliefs:
Mains wires with side of housing

The DIN connector is connected to the other side of the relay.
Low voltag side with DIN connector

The top is put back on the relay, this is how everything looks from above:
Top view of SSR housing

With everything closed the result is this:
Front view of SSR housing
Back view of SSR housing


Next step is the controller, but that has yet to be designed. Stay tuned!