| 摘要 |
The circuit has two power supplies: - A permanent supply: transformer and 12 V fixed voltage regulator. - A temporary one, provided with the aid of a comparator and three impedance transformers: LM324, IC3.2. An astable 555 AMV, IC2 multivibrator timer supplies the flashing (blinking) frequency, and C9 provides a short subsequent flashing. An IC4 exnor gate having the inputs: possible power supply and: AMV output permits current to flow in the quiescent state of output A3. A4 has a voltage in common with A3 only in the flashing state, and can be dialled using a plurality of changeover switches. A1 and A2 can optionally be used to supply a telephone bell receiver. The triac couplers switch in the zero crossing of the alternating voltage. The circuit is potted (encapsulated) with epoxy resin. The triacs are mounted in an insulated fashion on a cooling and mounting plate made from anodised aluminium 140/140/2 mm. The connections are of the plug-in type. Application: In offices, workshops, dwellings for the hard of hearing, somnolent residents and infants (small children), against alarm noises, enjoyment of music, in the case of appliances which are loud and impair hearing, as a telephone double-light bell.
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