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Simple Battery Low Voltage Beeper circuit provides an audible and visual low voltage warning for 12V battery powered devices. When the battery voltage is above the set point (typically 11V), the circuit is idle. If the battery voltage should fall below the set point, the LED will light and the speaker will emit a periodic beeping sound to warn of the impending loss of power. The circuit was designed for monitoring solar systems, but it could also be useful for automotive and other 12V applications. Specifications: Nominal operating voltage: 12V Idle current: 6ma Low Voltage Warning current: 15ma Theory: U2 provides a 5V regulated voltage reference. U1 is wired as a comparator, it compares the fixed 5V regulated voltage to the voltage on the wiper of VR1, that is proportional to the 12V supply. When the supply drops below the set point, the output of U1 goes low, turning on Q1 and powering the beeper and the LED. The beeper consists of U4, a tone generator, and U3, a low duty cycle pu...

A simple stereo audio amplifier is built around two 7905 negative-voltage regulators (IC1 and IC2) and a few discrete components. The circuit will also work with other 79XX regulators if appropriate power supply is used. Regulator IC 7905 works as an amplifier for the voltages applied to common pin2 (Ground or GND). Also check the LM317 audio amplifier, another interesting circuit. The minimal voltage drop over the standard 7905 is around 2V and it depends on the output current. Feedback resistors in the IC set the gain of the channel internally. The amplifier is a class-A audio amplifier. The minimal applicable value of R3 for the regulator 7905 is 8.2 to 10 ohms per 5W. Circuit diagram : 1W Stereo Amplifier with Voltage Regulators Circuit Diagram If the required output current for LS1 is below 100 mA, the value of resistor R3 can be 33 to 51 ohms per watt. The circuit works with any load resistance (R3 in parallel with LS1 as the load) under the condition that the regulator is ...

In this series of essentially the same principle with the power supply, but power supply is working to produce high voltage. And high voltage which is regulated by this series becomes more filtered and either used for electronic devices that are not easily damaged. High Voltage regulator schematics Component List R1_____________1K R2_____________470K R3_____________330K R4_____________20K C1_____________39uF 450V C2_____________39uF 450V C3_____________39uF 450V C4_____________39uF 450V C5_____________10uF 25V C6_____________220nF 250V C7_____________100nF 400V D1_____________1N4007 D2_____________1N4007 D3_____________1N4007 D4_____________1N4007 D5_____________1N4148 D6_____________1N4148 TR1____________MJE13005 TR2____________MPSA92 TR3____________MPSA42

This is a project of Simple Mains Voltage Monitor Circuit Diagram. Many electronics hobbyists will have experienced the following: you try to finish a project late at night, and the mains supply fails. Whether that is caused by the electricity board or your carelessness isn’t really important. In any case, at such times you may find yourself without a torch or with flat batteries. There is no need to panic, as this circuit provides an emergency light. When the mains fails, the mains voltage monitor turns on five super bright LEDs, which are fed from a 9 V battery (NiCd or NiMH) or 7 AA cells. A buzzer has also been included, which should wake you from your sleep when the mains fails. You obviously wouldn’t want to oversleep because your clock radio had reset, would you? When the mains voltage is present, the battery is charged via relay Re1, diode D8 and resistor R10. D8 prevents the battery voltage from powering the relay, and makes sure that the relay switches off when the mains vol...

All rechargeable battery has their specific level of charging and discharging, they are likely to get damage if the battery voltage exceeds that level. Here is a simple circuit battery voltage monitor used to indicate the state of battery by monitor them. The circuit of battery voltage monitor is fabricated and designed around an op-amp IC LM709 configured as comparator. Where bi-color LED is used as indicator and indicates three voltage level state of a 12V battery. Resistor R1 with potentiometer VR1 is used as potential driver of voltage monitor circuit.When voltage level rise above 13.5 volts, the output from IC 1 goes low as a result LED begins to emit RED light. Similarly, when the voltage fall below a preset level (10Volts) the output goes high and the LED start to emit GREEN light. Resistors R 3 and R 4 is used as current limiter of LED. PARTS LIST Resistors R1 = 1 KΩ R2 = 18 KΩ  R3, R4 = 680 Ω  VR1 = 10 KΩ (Potentiometer)  Semiconductors IC1 = LM709  D...

This is a Simple 1.5V Battery to 5V Voltage Converter Circuit Diagram. Stable and secure 5V DC (at 200mA max) from an ordinary 1.5V AA sized cell. At the heart of this circuit is IC1 MAX756 from Maxim, which is a CMOS step-up DC-DC switching regulator for small, low input voltage or battery-powered systems. Simple 1.5V Battery to 5V Voltage Converter Circuit Diagram MAX756 accepts a positive input voltage down to 0.7V and converts it to a higher pin selectable output voltage of 5V (or 3.3V). Typical full-load efficiency for the this IC is greater than 87%. Max756 combine a switch-mode regulator with an N-channel MOSFET, precision voltage reference, and power-fail detector in a single monolithic device. The MOSFET is a “sense-FET” type for best efficiency, and has a very low gate threshold voltage to ensure start-up under low-battery voltage conditions (1.1V typ). The circuit can be easily wired on a very small rectangular common PCB.All connections should be kept as short as possible. ...

This is the project of simple Period To Voltage Converter Circuit Diagram . The input signal drives ICD. Because ICD`s positive input (V+) is slightly offset to + 0.1 V, its steady state output will be around +13 V. This voltage is sent to ICC through D2, setting ICC`s output to +13 V. Therefore, point D is cut off by Dl, and CI is charged by the current source.  Assuming the initial voltage on CI is zero, the maximum voltage (^Cinax) is given by: When the input goes from low to high, a narrow positive pulse is generated at point A. This pulse becomes -13 V at point B, which cuts off D2. ICC`s V+ voltage becomes zero.  Period To Voltage Converter Circuit Diagram The charge on CI will be absorbed by ICC on in a short time. The time constant of C2 and R5 determines the discharge period— about 10 /is. ICB is a buffer whose gain is equal to (R& + R9)~Rg = lM5. ICD`s average voltage will be (1362f 1.545) + 2 = 1052/. RIO and C3 smooth the sawtooth waveform to a dc output.

This is smart High Voltage Power Supply 10kV Circuit Diagram. Be very carefull with this power supply because uses 220V mains and has 10KV at output. Characteristics: supply: 220V AC 50Hz mains Power: 15 Watts Ignition Voltage: 8KV . High Voltage Power Supply 10kV Circuit Diagram Sourced By: Circuitsstream

Monitors battery voltage, Three-LED Display. Connecting this circuit to the battery of your vehicle, you will always know at a glance the approximate voltage available. An indication of battery voltage is useful to the motorist for monitoring the battery's capacity to deliver current, and as a check on the efficiency of the dynamo or alternator. Threshold voltages of the Leds are set by means of two Zener Diodes (D6 & D10) plus two further Diodes wired in series (D4, D5 and D8, D9 respectively) adding a step of about 1.3V to the nominal Zener voltage. Parts:   R1 = 1k R2 = 100K R3 = 1k R4 = 3.3K R5 = 3.3K R6 = 1k R7 = 3.3K R8 = 3.3K Q1 = BC547 Q2 = BC547 Q3 = BC557 D1 = Red Led D2 = Amber Led D3 = 1N4148 D4 = 1N4148 D5 = 1N4148 D6 = BZX79C10 D7 = Green Led D8 = 1N4148 D9 = 1N4148 D10 = BZX79C12 Notes: Red LED D1 is on when battery voltage is 11.5V or less. This indicates a low battery charge. Amber LED D2 is on when battery voltage is comprised in the 11.5 - 13.5V range. This ...

Supply Voltage Monitor Circuit Diagram . A circuit for monitoring supply voltages of ±5 V and ±12 V is readily constructed as shown in the diagram. It is appreciably simpler than the usual monitors that use comparators, and AND gates. The circuit is not intended to indicate the level of the inputs. In normal operation, transistors T1 and T3 must be seen as current sources. The drop across resistors R1 and R2 is 6.3 V (12 –5 –0.7). This means that the current is 6.3mA and this flows through diode D1 when all four voltages are present. However, if for instance, the –5 V line fails, transistor T3 remains on but the base-emitter junction of T2 is no longer biased, so that this transistor is cut off. When this happens, there is no current through D which then goes out. Supply Voltage Monitor Circuit Diagram

Low Voltage Cut-Out Circuit diagram. This circuit will detect when the voltage of a 12v battery reaches a low level. This is to prevent deep-discharge or maybe to prevent a vehicle battery becoming discharged  to a point where it will not start a vehicle. This circuit is different to anything previously presented. It has HYSTERESIS. Hysteresis is a feature where the upper and lower detection-points are separated by a gap.  Low Voltage Cut-Out Circuit diagram : Low Voltage Cut-Out Circuit Diagram Normally,  the circuit will deactivate the relay when the voltage is 10v and when the load is removed. The battery voltage will rise slightly by as little as 50mV and turn the circuit ON again. This is called "Hunting." The off/on timing has been reduced by adding the 100u. But to prevent this totally from occurring, a 10R to 47R is placed in the emitter lead. The circuit will turn off at 10v but will not turn back on until 10.6v when a 33R is in the emitter. The value of this ...

Changing the voltage to frequency scale in the design of an electronic device is sometimes necessary. The series of articles voltage to frequency converter with the XR 4151 is one answer. Voltage to Frequency converter circuit with the XR 4151 is the idea of time in college, when there are projects to create a tool to hatch chicken eggs. It will be my neighbor also write articles incubators chicken egg-based microcontroller AT89C2051. Maybe there are friends who still remember to this project. Back to the topic of voltage to frequency converter circuit with the XR 4151. IC XR 4151 is a major component of voltage to frequency converter (Voltage to Frequency Converter). From voltage to frequency converter circuit with XR 4151 on the input signal circuit is a DC voltage level. IC XR4151 on voltage to frequency converter circuit serves to convert the voltage level coming into form in the development of the frequency change, where the output frequency range of voltage to frequency converter...

Description This device is designed to be a simple, inexpensive ‘comparator’, intended for use in a solar cell power supply setup where a quick ‘too low’ or ‘just right’ voltage indicator is needed. The circuit consists only of one 5V regulator, two transistors, two LEDs, five resistors, two capacitors, and one small battery. Although a 4-V battery is indicated, 4.5 V (3 alkalines in series) or 3.6 V (3 NiCd cells in series) will also work. The specifications of voltage regulator IC1 are mainly determined by the size and number of the solar cells and the current pull of the equipment connected to the output. Here the low-drop 4805 is suggested but other regulators may work equally well as long as you observe the output voltage of the solar cells. Transistors T1 and T2 are complementary types i.e. one each of the pnp and npn variety. Circuit diagram: Although the ubiquitous BC557B (pnp) and BC547B (npn) are indicated, any small-signal equivalents out of the junk box will probably do....

This Electronic Circuit Project of high voltage generator circuit. This high voltage generator was designed  with the aim of testing the electrical break-down protection used on the railways. These  protection measures are used to ensure that  any external metal parts will never be at a  high voltage. If that were about to happen,  a very large current would flow (in the order  of kilo-amps), which causes the protection  to operate, creating a short circuit to ground effectively earthing the metal parts. This hap-pens when, for example, a lightning strike hits  the overhead line (or their supports) on the  railways. This generator generates a high voltage of  1,000 V, but with an output current that is limited to few milliamps. This permits the electrical breakdown protection to be tested with-out it going into a short circuit state. The circuit uses common parts throughout: a  TL494 pulse-width modulator, several FETs or  bipo...

This circuit is used to monitor the battery voltage to display a dual-colored LED status of the battery to. If the LED “green”battery voltage exceeds 11.9 volts. If the yellow LED , battery voltage 11.9 to 11.5 volts. If the LED is “red” If the battery voltage below 11.5 volts. You can of course change the trigger points by the trimmer resistors and / or changing the value of the resistors in the divider. A dual op amp is used as a comparator. The green LED on the board, until the voltage exceeds 11.5 volts. The red LED illuminates when the voltage falls below 11.9 volts to the circuit. Therefore, in the 11.9 to 11.5 volts, both LEDs are on, producing a slightly yellow color. When the voltage falls below 11.5 V, the green LED , and now only the red LED flashes to indicate low voltage. Parts List R1=1K2 R2-3-4=680R R5=15K R6=10K R7-8-9-10=1K IC1=LM324 D1=5V6 /0.5W Zener D2-3-4-5=LED RV1=10K trimmer  Is recommended that multi-shaper for V1 and V2. Muti-trimmer makes it much easi...

Changing the voltage to frequency scale in the design of an electronic device is sometimes necessary. The series of articles voltage to frequency converter with the XR 4151 is one answer. Voltage to Frequency converter circuit with the XR 4151 is the idea of time in college, when there are projects to create a tool to hatch chicken eggs. It will be my neighbor also write articles incubators chicken egg-based microcontroller AT89C2051. Maybe there are friends who still remember to this project. Back to the topic of voltage to frequency converter circuit with the XR 4151. IC XR 4151 is a major component of voltage to frequency converter (Voltage to Frequency Converter). From voltage to frequency converter circuit with XR 4151 on the input signal circuit is a DC voltage level. IC XR4151 on voltage to frequency converter circuit serves to convert the voltage level coming into form in the development of the frequency change, where the output frequency range of voltage to frequency converter...

This circuit, designed on request, has proven to be useful to indicate when the voltage in a power supply line is changing from 120V to 240Vac. It can be used in different circumstances and circuits, mainly when an increase in ac or dc supply voltage needs to be detected. D3 illuminates when the line voltage is approaching 120V and will remain in the on state also at 240V supply. On the other hand, D6 will illuminate only when the line voltage is about 240V and will stay on because the latching action of Q1, Q2 and related components. C1, D1 and D2 provide a low dc voltage in the 4.5V - 6V range in order to allow proper operation of latch circuit and LEDs.  110 and 220V AC LED Voltage Indicator Circuit diagram     Parts: R1_____________470R 1/2W Resistor R2_____________220K 1/4W Resistor R3,R7__________470R 1/4W Resistors R4_______________1K 1/4W Resistor R5_______________2K2 1/4W Resistor R6_____________330R 1/4W Resistor C1_____________330nF 630V Polyester Capacitor C2_...

This is a simple Over - Under-Voltage Protection Of Electrical Appliances. This circuit protects refrigerators as well as other appliances from over and under-voltage. Operational amplifier IC LM324 (IC2) is used here as a comparator. IC LM324 consists of four operational amplifiers, of which only two operational amplifiers (N1 and N2) are used in the circuit. Over - Under-Voltage Protection Of Electrical Appliances Circuit Diagram The unregulated power supply is connected to the series combination of resistors R1 and R2 and potmeter VR1. The same supply is also connected to a 6.8V zener diode (ZD1) through resistor R3.Preset VR1 is adjusted such that for the normal supply of 180V to 240V, the voltage at the non-inverting terminal (pin 3) of operational amplifier N1 is less than 6.8V. Hence the output of the operational amplifier is zero and transistor T1 remains off. The relay, which is connected to the collector of transistor T1, also remains de energised. As the AC supply to the ele...

4.3 Voltage and Current Capacity of Cells The e.m.f. of a cell depends on the materials of its electrodes and the electrolyte. On the other hand, the amount of current an electric cell can produce in a given span of time depends on the quality of electrodes and the electrolyte it is made of. The table below shows the e.m.f. of some electric cells and the materials they are made of.  Cell e.m.f. Positive Electrode Negative Electrode Electrolyte 1 Simple cell (Zinc-acid) 1.5 Copper Zinc Dilute sulphuric acid 2 Leclanché 1.5 Carbon Zinc Sal ammoniac 3 Mercury 1.35 Steel Zinc Potassium hydroxide 4 Silver oxide 1.5 Silver oxide  Zinc    potassium or sodium hydroxide 5 Zinc air 1.4 Oxygen gas  Zinc   potassium hydroxide 6 Lithium air 3.8 Oxygen gas  Lithium  Organic carbonate 7 Lead-acid 2.2 Lead dioxide Lead Dilute sulphuric acid 8 Nickel-cadmium...