Washing Ready Indicator
Approx construction cost US$32
Has the washing machine finished? Avoid those washday blues!
The author's old washing machine gave long and faithful service. Unfortunately, when it did eventually fail, it was not possible to repair it economically.
The replacement washing machine is a famous brand, renowned for its high quality and long life. However, after using it for the first time, it became apparent that something that "old faithful" had was lacking in its successor.
This was a lamp that came on when it had completed the washing. The only way of knowing whether the new machine has finished or not is to look closely at the program switch or listen until the machine has not made a sound for some time. Taking the washing out promptly is important if you wish to re-load the machine or if you want to dry the laundry as quickly as possible.
A further point is that if the washing machine is situated in a garage or other place remote from the house, even a warning light will be of little help. You would have to visit it periodically to check whether it had finished its work.
The washing machine alarm circuit described here will give an audible signal (in the form of high-pitched bleeping) when the washing cycle has finished. If the machine has been left on a "rinse hold" setting, it will give a signal when the program has reached this point. This will prevent the user from forgetting about it and leaving the washing overnight in a machine filled with water.
Readers may find the circuit useful for other similar appliances and it has been tested successfully with tumble driers. Being battery-operated, the circuit is safe to construct and in operation. Also, because no modifications are made to the appliance itself, using the device will not invalidate any manufacturer's warranty.
More details on this construction project can be found in the May 2002 issue of EPE Online, the world's first web-delivered electronics and computing hobbyist magazine.
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