Tuesday, March 20, 2012

Ding dong bel Rumah
Skema Rangkaian bel Rumah
This simple circuit an low cost ding dong bell suitable for calling bell purposes. It is made around IC 8021-2 . IC 8021 has an in-built circuitry to produce ding dong sound each time its pin 3 is pulled low. The sound is stored in a 4 bit ROM.a complementary-pair, two-transistor amplifier is used to amplify the sound to a fair level of audibility. A piezo tweeter or an 8-ohm, 500mW speaker can be used at the output.




List Component bel Rumah:
R1: 1K 1/4W Resistance
C1: 10µF/12-25V Electrolytic Capacitance
T1: BC548/c8050 NPN transistor
T2: BC557/C8550 PNP transistor
IC1: 8021-2 ding dong sound generator
Ls1: Speaker tweeter 500 Mwatt - 5 watt
S1: switch on/off
S2: Switch Normally close
B1: 3V Cell
Each time when switch S2 is pressed, ding dong sound is produced twice. If you try to press switch S2 a second time when the first ding dong sound is still being produed, it has no effect whatever and the two ding-dong bell sounds will be invariably produced.S1 is the ON- OFF switch.Assemble the circuit on a good quality all pupose PCB.Don’t forget to use an IC holder for IC 8021.
IC 8021 Description
The 8021-2 is a ding-dong sound effect generator IC produced by LSI CMOS technology. With built-in RC oscillator and digital envelope circuits, minimal external components are required. This IC simulates the mechanical ding-dong sound, and is ideal for door bell application.
IC 8021 Features
- 1.3V to 3.3V operating voltage and low power consumption
- One-shot mode of 2 ding-dong playing sequences
- Standard TO-92 package form
- Dynamic speaker can be driven with external NPN transistor

IC 8021 Absolute Maximum Ratings
DC Supply Voltage ........................................... -0.3V to +5.0V
Operating Ambient Temperature .................... -10°C to 60°C
Storage Temperature ....................................... -55°C to 125°C

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