A dog with two tails and a mile of lamp posts comes to mind,
Spent all day "playing" (Mrs out)
Thought about all your suggestions, which at times sent my mind reeling, but put them all together and come up with a prototype,
it consists of a motor with an out of balance flywheel and a battery, (thanks to Tony and his short cut to accentric motors)I found that the volume can be altered by attaching to plastic sheet or rubber mounting, (always have been better at engineering than electronics,)
also found frequency can be adjusted with a pot' in circuit,
Took ideas from you all, comments from, irritating "buzz" to "hum" of a mobile phone etc,
It may not be an ideal answer and its far away from my original thread, but it's just what I wanted, (plus, it cost nothing as I had The Parts)
thank you all again for your time, knowledge and patience,
Baz,