I use an app on my iPhone called IntervalTimer. It allows you to create your own custom seessions either simple: 5 min warmup, 10x1min with 1min rest, 10 minute cool down or more complex: 5 min warmup, 10x1min with 1min rest, 5x2 min with 1 min rest , 10 minute cool down etc..
I use on the turbo with headphones - it has audible alerts and you can set different sounds for start, finish etc. so you could probably hear it from a jersey pocket.