This musical light alarm circuit is very simple, uses only 7 components, a LDR and a 3.6 V battery or 3 x 1.2 volts rechargeable batteries. The well-known UM66 is used as the sound generator and will ...

Here is an inexpensive circuit of a wireless cashbox security alarm realized using generally available low-cost components. Why it is inexpensive when compared to readily available wireless security ...