Serendipity strikes again, whilst walking towards the hospital I spied a chap repairing bicycles from a mobile bicycle repair van. Being ever curious I had to stop and have a chat with this guy, it turns out that he was asked to make a bicycle pump that a blind man could use. After a couple of false starts I came up with this idea of using a microprocessor and pressure transducer to drive a Piezoelectric electric horn.
The method I chose was to create a different tone for each pressure so that as you pumped up the tyre the tone changed in frequency. Due to the limited capacity of a pickaxe computer I was using. I chose only four values and used a 100 psi analogue pressure transducer. The value of the frequency was set by using fixed resistors of different values. The reason for the exceptionally large piezo electric horn was that I missed read the instructions, I expected a much smaller device than I had but the sound was particularly good, and it worked well.
The gentleman I made it for required a method of pumping up his tyre as he was blind who rode as Stoker on a tandem and wished to help in the preparation of the tandem. Therefore, needed a pump that he could use. Unbeknown to me he was too ride in the Services Memorial Challenge Ride to France later that year and was featured on Countryfile sometime later. Fortunately, I just happened to see the programme and was surprised to see my audio cycle pump being used.