Side Window Alarm

If the nearside house window is open, there is a real danger of hitting it and causing substantial damage, when the sliding door is opened. Several stories indicate that this is somewhat a common problem for van conversions with sliding doors. The fix here is to fit an alarm that sounds if you try to open the sliding door and the side window is already open.

Installing the Alarm

I mounted a microswitch with actuating roller (from junk box) on the window frame behind the stove, with the roller pressed against the window.

The schematic for the alarm shows that the window microswitch is wired in series with the door switch for the sliding door. When both switches are "on" the buzzer sounds at a rate of 1/2 s intervals. Since it may be the case that we want the side window and the door to be partly open, the buzzer is arranged to sound for only about 8 seconds before turning off. This is accomplished by wiring an astable and monostable with appropriate time constants in series, as is shown in the schematic.

The circuit fits into a 35 mm film cannister and is located next to the sliding door behind the door-track cabinetry above the fridge (at ear height!). It is powered from a distribution block in the Technical Cupboard (the cupboard over the fridge). This distribution block uses the power wires (12 AWG) left over from rewiring the Omni-Step.

Window Alarm

The problem: the sliding door can collide with the open window.

Microswitch with roller arm mounted on nearside window frame.

The alarm circuit and buzzer.