For home circuit diagrams
15 seconds delayed switch-off. A good idea for bedroom lamps
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This circuit will light a lamp at a remote location when the doorbell switch is pressed. This circuit should only be used with the solenoid type doorbells, the electronic type that play tunes will not work here.
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Detects if the door-bell has rung in your absence
Also suitable for different electric appliances
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A multiple input combination loack using CMOS counter IC's. Flexibility and code change is allowed by changing output connections.
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High sensitivity, portable temperature comparator Detects draughts around doors, windows, etc.
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Three circuit options. Can be synchronized to Christmas tree flashing lights
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This circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch can be moved from within the house which will light a lamp in the door bell switch. The lamp can illuminate the words "Please Wait" for anyone with walking difficulties.
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Agreeable, very close sound imitation. Suitable for sound effects, door-bells etc.
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The IC is a quad 2 input "AND" gate, a CMOS 4081. These gates only produce a HIGH output, when BOTH the inputs are HIGH. When the key wired to 'E' is pressed, current through R1 and D1 switchs Q5 on.The relay energises; and Q5 is 'latched on' by R8. Thus, the Alarm is set by pressing a single key,say one of the two non-numeric symbols.
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This circuit uses a synthesized sound chip from Holtek, the HT-2811. This reproduces the sound of a "ding-dong" chiming doorbell. Additionally, the circuit includes a CMOS 4026 counter display driver IC to count your visitors.
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