Our client was concerned about reversing her high backed wheelchair and wanted an alarm which would activate when there were obstructions behind such as people or objects.
An ultrasonic reversing alarm electronics kit by Belgian company Velleman was purchased from Maplin Electronics. This uses a similar principle to reversing alarms on motor vehicles. The kit was assembled and installed in two boxes - one containing the electronics and mounted at the rear of the wheelchair, and a second narrow box mounted under the arm of the wheelchair, containing the battery, on/off switch and sounder.
After some use, it became clear that the audible alert could be drowned out in noisy traffic, so an additional sounder and driver circuitry was added so the volume could be increased at the flick of a switch.  
Allows the alarm unit to be turned on and off easily Made by Belgian company Velleman Detects people or objects behind the wheelchair arrownext.png arrowprev.png logo.jpg
Harrogate and Ripon Group