Versatile Micropower Battery Protector

Protect your expensive batteries from discharge damage with this mini-sized electronic cutout switch. It uses virtually no power and can be built to suit a wide range of battery voltages.
Main Features

• Disconnects load at preset battery voltage
• Automatically reconnects load when battery recharged
• Ultra-low power consumption (<20ma)
• Miniature size
• 10A maximum rating
• Suitable for use with 4.8-12.5V batteries
• Transient voltage protection (optional)
Suitable for use in...

• Cars, boats & caravans
• Security systems
• Emergency lighting
• Small solar installations
• Camera battery packs
• Many other low-power applications
Picture of the project:





Back in May 2002, we (Silicon Chip) presented the "Battery Guardian", a project designed specifically for protecting 12V car batteries from over-discharge. This unit has proven to be very popular and is still available from kit suppliers. This new design does not supersede the Battery Guardian – at least not when it comes to 12V car batteries. Instead, it’s a more flexible alternative that can be used with a wide range of battery voltages.

Parts layout:





In this new "Micropower Battery Protector", we’ve dispensed with the low-battery warning circuitry and the relatively cheap N-channel MOSFET used in the Battery Guardian in favour of a physically smaller module that steals much less battery power. It costs a little more but can switch lower voltages, allowing it to be used with 6V & 12V lead-acid batteries and 4-cell to 10-cell NiCd and NiMH battery packs.

PCB layout:


Most battery-powered equipment provides no mechanism for disconnecting the batteries when they’re exhausted. Even when the voltage drops too low for normal operation, battery drain usually continues until all available energy is expended. This is particularly true of equipment designed to be powered from alkaline or carbon cells but retro-fitted with rechargeables.

Circuit diagram:



Another example is emergency lighting and security equipment designed to be float-charged from the mains. In an extended blackout period, the batteries can be completely drained and may not recover when the mains power is finally restored.

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Classification Transistor Amplifier

A transistor amplifier must have a DC biasing circuit for several reasons. Especially, we will need two separate voltage supply to provide the desired class bias voltage to the emitter-collector and emitter-base. In fact it is actually only done in certain applications, but found that biasing voltage can be obtained separately from a single supply. Second, the transistor is very sensitive to temperature and creates a condition called thermal runaway. Thermal runaway will quickly destroy the bipolar transistor, because the collector current out of control quickly and will improve to the level of damage and the temperature will rise if there is no stabilizing the temperature at the amplifier to eliminate this effect.

A common class for refractive surgery is a Class A, AB, B, and C. All of these classes use the same arrangement of the components to her on the operation of the DC bias transistor Q-point or different.

Location of the variation bias point Q for different amplifier classes

Class A bias on the amplified signal current flows in the form of a full circle, 3600 so that the output signal never reaches saturation or cutoff, so stay on the operation of the linear parameter. The output represents the strengthening of the similarity of the input signal accurately. Because of low efficiency, this class is typically used only for small signal (small-signal) which is not power applications, especially as a low distortion linear amplifier in the RF and IF. Reduction in efficiency occurs because of the DC power needed over time with or without the RF input signal to generate a constant current always flows through through this amplifier.

Class AB bias is obtained by lowering a little Q-point on the amplifier. Efficiency is slightly higher than Class A due to the static output current (Ic) flowing through the amplifier will be smaller and its shape is not a full circle, usually 3000 for power amplifier applications. But the single-ended power amplifier class AB will produce more distortion than Class A because of the clipping on the output. Class AB is also a common bias for push-pull audio power amplifier and linear RF power amplifier is a push-pull

Class B has a very high level of efficiency. Currently there is no input signal, the power dissipation that occurs close to zero. This is because almost no collector current flows, because the bias is reduced to cope with the slightest connection (junction) 0.6 V base-emitter junction. The output signal is close to 1800 in which this condition occurs because the RF signal is a half circle forward bias on the basis of the semi-circle while the other is the reverse bias on the emitter-base, causing a reduction in output signal.

Class C amplifiers are even more efficient than Class B because it only consumes less leakage current when no RF input signal. When the input signal is given, the class C amplifier will be strengthened less than a half circle and will only supply a pulse at its output terminal. Konduksinya angle of 1200 or less because of the connection (junction) emitter-base reversed a bit of bias

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Workings of STR IC Regulator Power Supply

The meaning STR in this article for example is a Sanken regulator series and Fairchild series STR-F/G/W KA05Q Is an ic Quasy Resonant Flyback (QRF) Swiching Regulator comprising (a) control IC and (b) power MOSFETs that are packed into a single unit. The regulator is designed so that only requires a few external components.

How it works :

A. UVLO (under voltage lock out)

Regulators will start working when the voltage Vcc start-up on pin-4 reaches 16V. Once the power supply voltage Vcc further work will be reimbursed through a switching transformer supplied from a diode rectifier. At the time the circuit was working when the voltage Vcc is less than 15V, the regulator controls will still work. regulator will stop working (protectionism) if the supply voltage Vcc drops to less than 11V.

  

2. Feedback control (pin-1)

PWM regulators work using the system, wherein the output voltage B + to stable controlled by the feedback circuit of the output voltage B + >>> >>> photo-coupler pin-1. A capacitor mounted on the pin-1 is used to prevent noise disturbance if anyone does not interfere with the working system.

  

3. Soft start (pin-5)

When the power is turned on first, then the circuit has not been working behind the Uman because there is no output voltage B +. This causes a heavy current on the MOSFET start. To prevent this, the regulator is equipped with soft start circuit internally and an external filter kapasitr.

If the power supply is used to monitor for example, the frequency of the regulator needs to be synchronized. External synchronization signal can be input through pin-5s

  

4. Protectors

Regulators are equipped with all sorts protector.

• Over-current protector (OCP) or Over Load protector (OLP). For example, if there is damage to flyback or def yoke, it will cause the load voltage B + over. If there is such a case the regulator will die protectionism so that IC is not damaged. For over current sensor is a resistor with a small value that is placed on pin-2 to the ground.
• Short protector. If the output voltage B + short, the regulator turns off protectionism.
• Over-voltage protectors (OVP). Regulators are not equipped with a surge protector so if the feedback path disconnected can cause the output voltage of the transformer switching regulator power up or damaged .. With OVP protectionist regulator will die if the voltage supply Vcc pin-4 rise above 22.5v.
• Thermal protector. Regulators will stop working if the temperature reaches 140 degrees Celsius.

6. Auto start.

Regulators will start automatically if the auto turns itself (protectionism) after OVP or OCP

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Circuit of Simple Temperature Detector

This is an explanation about circuit of simple temperature detector. In many ways, the development of science and technology is getting easier for human activities (especially those who are ready to receive it), the various creations of human creativity in any variety of small things to things that are not small.


create excessive heat detection circuit of an object (could be: water, body temperature, etc.) using a very simple circuit.

This Image of Simplified Circuit Temperature Detector

The circuit consists of:

Temperature sensor (thermistor or the like)
potentiometer 10 K
741 Op Amp
resistor
output: Bi Color Led

Explanation The Circuit

as an automatic switch we use a voltage divider between the thermistor and potentiometer (to set accuracy) and the incoming voltage from the voltage divider had entered the LM 741 op amp and output from the LED will change color automatically.
note: the output can be replaced by buzzer

when heat temperature

when cold temperatures

Thats the circuit of simple temperature detector , this circuit can be used to detect your health, good healthy living ( vida sana ).

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50Watt Audio Power Amplifier Circuit with LM3876

My account of architecture of this activity was to advance a bunched architecture for a stereo amplifier can be chip by a amiss (but the complete affection conscious!) Living apprentice at a university or a academy dormitory.

The amplifier feeds a brace of speakers with two LM3876 amplifier chip circuits (50 watts per channel), or a brace of headphones Meier Crossfeed through a clarify and a bifold OPA2134 Opamp. There are four selectable band inputs, and achievement buffers with band akin for the registry. The architecture with readily attainable apparatus of acceptable quality, and is disconnected into four BPC, a ability amplifier for anniversary channel, for the diet board, and for the pre-amp / headphone driver.

The achievement selector is beatific to pins J1 and J3. Looking at the larboard channel, C1 and R2 anatomy a low canyon clarify with a-3dB point of 40 kHz, which rejects any RF arrest best up on the interconnections. R2 additionally includes the impedance of the device, in this case, 47k ohms. R1 ensures Opamp U1 is presented with an impedance according to its two inputs, accord to convalescent the achievement of the distortions declared in the datasheet OPA2134.

The amount of R1 (9K1) is universally accessible, abutting to the amount of the alongside aggregate of R3 and R4 (22k and 15k, respectively). R3 and R4 set the accretion at that time, aloof beneath 2.5 in this case. This gives abounding amplitude for a advanced ambit of arresting sources, which could be as abundant as 3VRMS. In this case, the aiguille achievement voltage of 10.6V would be accomplished with the activity to accumulation ± 15V.

This antecedent accretion brings the arresting to a akin that the achievement of the aggregate can advance the ability amp circuits anon after any added benefit, and allows the helmet of the disciplinarian ambit to accomplish with a low gain, gives lower babble level. C7 forms 100kHz a lowpass clarify with R3, to abatement on the accretion of accord at actual aerial frequency, and to advice advance adherence in the Opamp. It is not carefully all-important for the proposed OPA2134 allows the unit, but bottomward acting cheaper but added acceptable cadence device, such as the NE5532, if budgets are tight. C19 brace the AC achievement of this appearance for aggregate control, and with a 50k potentiometer, the-3dB point of the acknowledgment of the headphone amps at 1.4Hz (power amp has added HIGH PASS FILTER). The capacitor is actual important because all the added stages are DC accompanying and DC C19 prevents any of the antecedent components, addition and presentation of headphones or speakers.

Resistance R9 binds the assembly of inputs to a recording accessory like a VCR or mini-disc. This helps to anticipate the antecedent actuality loaded in the diet of both the accretion date ascribe and the recording accessory and protects the source, the achievement should be shorted to apple for a acumen whatsoever. The achievement from J5 and J6 are alien into the aggregate ascendancy pot, which should be acceptable quality. Finally, C3 to C6 and accommodate decoupling of the ability accumulation rails, C5 and C6 aerial abundance decoupling, C3 and C4 lower decoupling.

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60W inverter using transistors

Here is the circuit diagram of a fully transistorized inverter that can drive up to 60W loads. Transistors Q1 and Q2 forms a 50Hz astable multivibrator. The output from the collector of Q2 is connected to the input of the Darlington pair formed by Q3 and Q4.Similarly the output of Q1 is coupled to the input of the pair Q5 and Q6. The output from the Darlington pairs drive the final output transistors Q7 and Q8 which are wired in the push pull configuration to drive the output transformer.

Circuit diagram.

Notes.

The circuit can be assembled on a vero board.

T1 can be a 230V primary to 9-0-9V, 6A secondary transformer.

Transistors Q4, Q6, Q7 and Q8 must be fitted with heat sinks.

Use a 12V, 7Ah battery for powering the inverter.

Slight adjustments can be made on the value of R3 and R4 to get exact 50Hz output.

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Circuit Serial To LCD

In making an electronic device using a microcontroller, we often faced with shortages in ports for line I / O or LCD viewer. In the article series LCD with 74HC595 Serial To this there is a solution to overcome the lack of ports or pins of the microcontroller is to convert the parallel bus system such as the LCD into a serial sequence To Serial LCD with 74HC595 this. The series of LCD Serial To change the system of parallel bus into a serial LCD IC 74HC595 premises. 74HC595 IC on circuit Serial To this LCD is a digital IC that it functions as a serial to parallel shift register is equipped with a latch. With the functions of the IC 74HC595 parallel LCD bus system in enter in great numbers have turned into a serial of microcontroller and be a series of Serial LCD with 74HC595 for this. Now with a range Serial To LCD with 74HC595 for the microcontroller is expected no more stories lack the pin / port of the microcontroller in the manufacture of electronics equipment.

Click Image for full display

      Circuit Serial Line For LCD with 74HC595

•      Clock as input clock of the microcontroller
•      Data as input data for the LCD display
•      Enable is the read data selector LCD mode or Disable
•      LED light path to control the LCD background
•      Potensimeter on the LCD serves to adjust the brightness of LCD display
  

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