Any prolonged stay of the baby in wet diapers he can only damage: diaper rash, other skin damage almost inevitable. However, not every child informs its parent about the incident. So...
Schematic diagram of the device shown in the figure. Here e is the actual sensor - two perforated metal electrode size 15h40 mm (Fig. 1), separated by several layers of dry gauze and sealed with a rubber ring. The electrodes are placed in proximity associated with the electronic device twisted pair or thin shielded wire.
Fig. 1
The input stage of the device is made on the transistor VT1. The transistor is closed and the voltage on the collector is close to zero, if the interelectrode resistance R exceeds the threshold Rпор@60(SP-1), where R is in kiloomah, SP - volts. The VT1 transistor goes into saturation and the voltage at its collector becomes close to +PI with re < Rпор.
On DD1 chip is assembled sound generator alarm sound. He remains in the ground state, if the transistor VT1 is closed, and excited, forming an acoustic alarm signal, if VT1 is open.
In what part zapelenutogo baby should "fit" the electrodes, parents will decide. It is only important to ensure that the matching conductors were placed with him in the side and so that under any circumstances he could not be a little confused. If any doubt on this score make this connection easily break off, for example, wire sew-2 of 0.1.
The design of the electrodes can be, of course, another. It is only important that they are safe for the baby, had sufficient space it out in direct experiment) and allowed sterilization.
The power source device can be any galvanic battery voltage 9...6 V. the Current consumed in the standby mode does not exceed a few microamperes, in the alarm mode less than 3 mA.
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