pulsing or flashing text box

Hello,

I'm kind of stuck with a school project where we have to design the heating system for a virtual builing.

I'd like to add a slight pulsing action to the 3 heating units (pulsing red) and 3 cooling units (pulsing blue). The 6 units are shown on the first tab called 'P&ID'. In the upper left corner of the first sheet sits a blue colored pulldown menu. Depending on the selected outside temperature (in centigrade) the heating/cooling system comes on. Each group will give a presentation about their design. I would like to add a little touch with a delicate pulsing thing.

I can find lots of info on making cells flash but not on how to make a text box flash. I tried to create a macro in VBA and point it to the first textbox (textbox 50) but that did not work. All I need is an incremental puls for 8 preset temperatures. At 20 degrees centigrade (70 F) both heating and cooling are shut off. How can I get these units to sort of mimic the kiloWatts being consumed at the other preset temperatures?

Thanks for any pointers,

maurits

PS I can select my excel file with the 'manage attachments' button but the file won't upload. It's dead. What do I do wrong?