This was a project that I made for my brother who is a massive Father Ted fan. (Apologies for not having photos for every step and some are taken at a different stage in the build)
In the episode entitled, Flight into Terror, Dougal buys a tape dispenser in the duty free whilst they are travelling back from the fictional pilgrimage of Kilnettle. The tape dispenser, tells you how much tape you have used as you can see in the video below (first usage is at about 4:01 into the video):
For years, my brother has been after one of these and I finally got around to making him one. It measures the tape pulled and plays back clips from the show that correspond to the length. It also has a bonus feature which I shall reveal in a future post!
I bought two cheap dispensers that were on sale in Aldi – one to take apart as a test and one for the good model. (Also available from Tiger)It took a bit of work, but by sliding a screwdriver under the plastic base I was able to work my way around the base and take it off. It was held on by glue so I needed to be careful in a few spots.
After removing the base, I could see the weight to hold it steady during use was achieved by some cement. Luckily enough, this came out quite easily after a tap or two.
Looking inside I could see there was some good space inside and began to look at possible means of measuring the movement of the tape reel. My initial thoughts were to look at something like an optical line reader in conjunction with a black/white disk attached to the tape reel. However, this wasn’t very practical as the disk would stick to the side of the tape and I thought it may cause blockages. Also, as the tape was used up, the disk would have a greater diameter than the reel and I wasn’t happy with this aesthetically.
Next idea was to use some means of direct contact with the tape reel as it spins and feed that back to a rotary encoder. This was discounted due to the complexity of the mechanism required to maintain contact with the tape reel.
I had played around with infrared (IR) sensors in the past so decided to test out one that I had purchased with the idea of finding a project for at some stage. The TCRT5000 is a cheap IR sensor combo of an IR led and IR receiver in one small package. As the tape has a shiny surface, i wasn’t certain of the results I would get. If the reflectance didn’t change enough when the tape moved, it wouldn’t be a measurable parameter. I dremelled out a hole for the sensor and hooked it up the arduino using the analog read example. Disappointingly, it worked but not quite as expected.
It detected movement of the tape, but that was due to the tape reel moving vertically upwards as the tape was removed. It was a possible monitoring mechanism but was difficult to characterise. Plus, it was dependent on the users tape removal technique. My technique was to pull at a 45º angle which caused the movement upwards. If they pulled the tape horizontally outwards, there would be no change in height and therefore nothing to detect.
Onto a hall sensor…..in part 2 🙂