Author: Manikandan KJ ©kjmindia.in Here is another audio annunciator used in factories, industries, hospitals, auditoriums, theatres, etc. to indicate the power failure and resumption. The circuit will give a long beep on power resumption and an intermittent beep when power fails. The power failure alarm circuit that I posted earlier will activate the alarm (continuous tone) only for a few …
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Author: Manikandan K J This circuit produces an audible alarm when the water level in a rain or water tank rises above a preset level and overflows. It will sound an alarm whenever the water level reaches the top position in the overhead tank, thus it alerts one to turn off the motor to prevent water wastage. The purpose of …
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Author: Manikandan K J This is a very simple circuit built using only a few components to detect ac mains power failure and its resumption. The heart of the circuit is the most popular timer Ic 555 which is wired as monostable multivibrator. Battery, Diode D1, D2, Led L2 and resistor R2 are wired in such a way that the …
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Voltage fluctuations and power cuts adversely affect various electrical appliances such as Tv, music system, refrigerator, etc. Here is a simple and inexpensive circuit using opamp Lm358 to disconnect the equipment during high and low voltage. We can also use LM324 to design this circuit by using only the two op amps out of the four. We can also design …
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Battery Level Indicator Circuit Using Dual Op Amp Ic LM358 To Monitor 12V Battery’s full, normal and low level. Pаrtѕ Uѕеd: Rеѕіѕtоrѕ: (1/4 Wаttѕ)R1 – 10KR2 – 10KR3 – 10K (рrеѕеt)R4 – 10K (рrеѕеt)R5 – 1.5KR6 – 1.5KR7 – 1KR8 – 1.5KR9 – 1.5K …
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Pаrtѕ Used:IC:U1 – 555 Tіmеr Rеѕіѕtоrѕ (All 1/4 Watts):R1 – 22KR2 – 8.2KR3 – 470E Cарасіtоr:C1 – 0.001(сеrаmіс disc) Dіоdе:D1 – 6v, 500mW (Zener) LED – Any соlоr12V BаttеrуGeneral Purpose PCB Cіrсuіt Dеѕсrірtіоn: The average сurrеnt drаіn іѕ 1mA оr lеѕѕ duе tо thе low dutу сусlе оf thе flаѕhіng LED. Thе timer іс 555 wіll trіggеr the LED on when …
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Pаrtѕ Used: Rеѕіѕtоrѕ: (1/4 Wаttѕ)R1 – 10KR2 – 10KR3 – 10K (рrеѕеt)R4 – 10K (рrеѕеt)R5 – 1.5KR6 – 1.5KR7 – 1KR8 – 1.5KR9 – 1.5K IC:U1 Dual Oр-Amр LM358 LEDѕ:RеdGreenYellow Fuse:100mA12V Bаttеrу General purpose PCB Circuit Description:Thіѕ сіrсuіt mоnіtоrѕ thе 12V battery vоltаgе. It provides an іndісаtіоn оf nоrmаl supply vоltаgе аѕ wеll аѕ lоw аnd high vоltаgе. RV1 аnd RV2 …
Read More »Parts Used:Transistor : BC547 (Q1)Resistor (All are 1/4Watts)R1 – 10KR2 – 1KR3 – 1K Diode:D1 – 6V, 500mW ZenerD2 – LED (any color)Circuit Description:This circuit indicates a warning whenever the battery voltage falls below the level set by 10K pot. It can indicate that the battery is defective or needs charging if cranking drops battery voltage below preset “safe” limit. 12v battery monitor circuit …
Read More »Parts Used: Resistors: (All are 1/4 Watts) R1 – 1M R2 – 470K R3 – 8.2K R4 – 680E Diodes: D1 – 5.1 Zener (500mW) D2 – IN4148 L1 – LED (any color) IC: U1 – Op-Amp 741 Battery: BT1 – 12V Switch – On/Off Circuit Description: A 741 op-amp is employed as a voltage comparator. The non inverting input …
Read More »Author: Manikandan K J Components Required:Resistors (All 1/4W)R1 – R6 – 1MR7 – R12 – 220KR13 – R17 – 1KR18 – 3.3KR19 – 1MR20 – 100K (Preset)R21 – 1KR22 – 1.5K Capacitors:104(0.1uF) – Ceramic Disc – 1 no.100uF,25V – 1 no.470uF,40V – 1 no. IC:U1- CD4049 (with Base)U2-555(with Base) Diodes:D1 – LEDD2 & D3- IN4148DB1- W04 (Bridge Rectifier) Transistor:S8550 PNP Relimate Connector:Sensor – 8 …
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