Voltage Controlled Oscillator

In most cases, the frequency of an oscillator is determined by the time constant RC. However, in cases or applications such as FM, tone generators, and frequency-shift keying (FSK), the frequency is to be controlled by means of an input voltage, called the control voltage. This can be achieved in a voltage-controlled oscillator (VCO). A VCO is a circuit that provides an oscillating output signal (typically of square-wave or triangular waveform) whose frequency can be adjusted over a range by a dc voltage.

Voltage Controlled Oscillator Block Diagram :

An example of a VCO is the 566 IC unit, that provides simultaneously the square-wave and triangular-wave outputs as a function of input voltage. The frequency of oscillation is set by an external resistor R1 and a capacitor C1 and the voltage Vc applied to the control terminals. Figure shows that the 566 IC unit contains current sources to charge and discharge an external capacitor Cv at a rate set by an external resistor R1 and the modulating dc input voltage.

A Schmitt trigger circuit is employed to switch the current sources between charging and discharging the capacitor, and the triangular voltage produced across the capacitor and square-wave from the Schmitt trigger are provided as outputs through buffer amplifiers. Both the output waveforms are buffered so that the output impedance of each is 50 f2. The typical magnitude of the triangular wave and the square wave are 2.4 Vpeak.to-peak and 5.4Vpeak.to.peak.

The frequency of the output waveforms is approximated by : fout = 2(V+ - Vc)/R1C1V+

Voltage Controlled Oscillator Circuit Diagram :

Figure shows the pin connection of the 566 unit. The VCO can be programmed over a 10-to-l frequency range by proper selection of an external resistor and capacitor, and then modulated over a 10-to-l frequency range by a control voltage, Vc The voltage controlled oscillators (VCOs) are commonly used in converting low-frequency signals such as EEG (electro-encephalograms) or ECG (electro-cardiograms) into an audio­frequency (AF range).

Source : http://www.ecircuitslab.com/2012/09/voltage-controlled-oscillator.html

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Automatic Room Power Control

          An ordinary automatic room power control circuit has only one light sensor. So when a person enters the room it gets one pulse and the lights come ‘on.’ When the person goes out it gets another pulse and the lights go ‘off.’ But what happens when two persons enter the room, one after the other? It gets two pulses and the lights remain in ‘off’ state. The circuit described here overcomes the above-mentioned problem. It has a small memory which enables it to automatically switch ‘on’ and switch ‘off’ the lights in a desired fashion.

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   The circuit uses two LDRs which are placed one after another (separated by a distance of say half a metre) so that they may separately sense a person going into the room or coming out of the room. Outputs of the two LDR sensors, after processing, are used in conjunction with a bicolour LED in such a fashion that when a person gets into the room it emits green light and when a person goes out of the room it emits red light, and vice versa. These outputs are simultaneously applied to two counters.

   One of the counters will count as +1, +2, +3 etc when persons are coming into the room and the other will count as -1, -2, -3 etc when persons are going out of the room. These counters make use of Johnson decade counter CD4017 ICs. The next stage comprises two logic ICs which can combine the outputs of the two counters and determine if there is any person still left in the room or not.

   Since in the circuit LDRs have been used, care should be taken to protect them from ambient light. If desired, one may use readily available IR sensor modules to replace the LDRs. The sensors are installed in such a way that when a person enters or leaves the room, he intercepts the light falling on them sequentially—one after the other.

   When a person enters the room, first he would obstruct the light falling on LDR1, followed by that falling on LDR2. When a person leaves the room it will be the other way round. In the normal case light keeps falling on both the LDRs, and as such their resistance is low (about 5 kilo-ohms). As aresult, pin 2 of both timers (IC1 and IC2), which have been configured as monostable flip-flops, are held near the supply voltage (+9V).

   When the light falling on the LDRs is obstructed, their resistance becomes very high and pin 2 voltages drop to near ground potential, thereby triggering the flip-flops. Capacitors across pin 2 and ground have been added to avoid false triggering due to electrical noise.

   When a person enters the room, LDR1 is triggered first and it results in triggering of monostable IC1. The short output pulse immediately charges up capacitor C5, forward biasing transistor pair T1-T2. But at this instant the collectors of transistors T1 and T2 are in high impedance state as IC2 pin 3 is at low potential and diode D4 is not conducting.

   But when the same person passes LDR2, IC2 monostable flip-flop is triggered. Its pin 3 goes high and this potential is coupled to transistor pair T1-T2 via diode D4. As a result transistor pair T1-T2 conducts because capacitor C5 retains the charge for some time as its discharge time is controlled by resistor R5 (and R7 to an extent). Thus green LED portion of bi-colour LED is lit momentarily.

   The same output is also coupled to IC3 for which it acts as a clock. With entry of each person IC3 output (high state) keeps advancing. At this stage transistor pair T3-T4 cannot conduct because output pin 3 of IC1 is no longer positive as its output pulse duration is quite short and hence transistor collectors are in high impedance state.

   When persons leave the room, LDR2 is triggered first, followed by LDR1. Since the bottom half portion of circuit is identical to top half, this time, with the departure of each person, red portion of bicolour LED is lit momentarily and output of IC4 advances in the same fashion as in case of IC3.

   The outputs of IC3 and those of IC4 (after inversion by inverter gates N1 through N4) are ANDed by AND gates (A1 through A4) and then wire ORed (using diodes D5 through D8). The net effect is that when persons are entering, the output of at least one of the AND gates is high, causing transistor T5 to conduct and energise relay RL1. The bulb connected to the supply via N/O contact of relay RL1 also lights up.

   When persons are leaving the room, and till all the persons who entered the room have left, the wired OR output continues to remain high, i.e. the bulb continues to remains ‘on,’ until all persons who entered the room have left.

   The maximum number of persons that this circuit can handle is limited to four since on receipt of fifth clock pulse the counters are reset. The capacity of the circuit can be easily extended to handle up to nine persons by removing the connection of pin 1 from reset pin (15) and utilising Q1 to Q9 outputs of CD4017 counters. Additional inverters, AND gates and diodes will, however, be required.

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12V Flourescent Lamp Inverter

Fluorescent tubes use far less energy than incandescent lamps and fluorescent tubes last a great deal longer as well. Other advantages are diffuse, glare-free lighting and low heat output. For these reasons, fluorescent lighting is the natural choice in commercial and retail buildings, workshops and factories. For battery-powered lighting, fluorescent lights are also the first choice because of their high efficiency. The main drawback with running fluorescent lights from battery power is that an inverter is required to drive the tubes.

12V Fluorescent Lamp Inverter Circuit diagram:

Fig.1: two switch-mode circuits are involved here: the DC-DC inverter involving IC1, Q1 & Q2 and the fluoro tube driver which converts high voltage DC to AC via IC3 and Q3 & Q4 in a totem-pole circuit.

Inverter efficiency then becomes the major issue. There are many commercial 12V-operated fluorescent lamps available which use 15W and 20W tubes. However, it is rare to see one which drives them to full brilliance. For example, a typical commercial dual 20W fluorescent lamp operating from 12V draws 980mA or 11.8W. Ignoring losses in the fluorescent tube driver itself, it means that each tube is only supplied with 5.9W of power which is considerably less than their 20W rating. So while the lamps do use 20W tubes, the light output is well below par.

Warning:

This circuit generates in excess of 300V DC which could be lethal. Construction should only be attempted by those experimenced with mains-level voltages and safety procedures.

Source: http://www.ecircuitslab.com/2011/08/12v-flourescent-lamp-inverter.html

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1 Zener Precise Limiter Circuit Diagram

A limiter 1 Zener Precise Limiter Circuit Diagram that requires matched zener diodes can instead use one zener with a full-wave diode bridge. The circuit`s two limits are nearly equal when determined by the same zener—only two pairs of forward diodes need to be matched. For best results, an integrated quad of diodes can be used. But, after testing the circuit, four single controlled-drop diodes and four ordinary diodes gave about the same accuracy (better than 0.5%). 

 1 Zener Precise Limiter Circuit Diagram

Because the limiting level can be adjusted, zener tolerance can be adjusted out. Gain stability can be optimized by connecting the inverting input to the first op amp to the output of the second to make the circuit inherently unity-gain. 

The zener voltage must be increased to 8.2 V to compensate for the two diode drops. Placing small capacitors across the resistors in the loop stabilized the circuit adequately and response is orders of magnitude faster than conventional circuits. Moreover, it`s limited primarily by the op amp`s slew rate.

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Door alarm for Fridge

This circuit will help you to save your electricity bill.  Incase if you leave the fridge door open more than twenty seconds. The circuit consumes very little current as it can operates by a 3 volts battery. You can enclose this whole circuit in a small box and keep inside the fridge.

R2 is a photo resistor. Normally photo resister has a low resistance but when you close the fridge door, with the darkness the photo resister’s resistance will go high. When you open the door fridge lamp will light and photo resister’s resistance goes down.

 Then the IC1 start its action. You can set the preset according to your wish but in this circuit it is set for 20 seconds delay. After 20 seconds the piezo starts beeps until you close the door.

Remember not to place the alarm box inside the freezer try to place it near the lamp.

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RING BELL ELECTRONIC CIRCUIT USING NE555 DIAGRAM

RING BELL ELECTRONIC CIRCUIT USING NE555 DIAGRAM

This circuit produces oscillating frequency around 1kHz, and able to be converted by changing the value of resistor R1. The speaker will produce a long beep sound with 1kHz frequency. Here is the schematic :

Parts list :

•     Resistor R1 : 10k ohm
•     Resistor R2 : 56k ohm
•     Capacitor C1-C2 : 0.01 uF
•     Polar capacitor C3 : 1 uF/15V
•     IC timer : NE 555
•     Speaker : 8 ohm 0.5 W
•     ON/OFF switch
•     5-15V Power supply

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AFX Slot Car Lap Counter

AFX slot car sets are very enjoyable but you can increase the fun with a lap counter. This circuit will count from 00 to 99, with independent counters for each track. The sensing device used is a Hall effect sensor (UGN3503; available from Dick Smith Electronics). One of these sensors is glued under a section of each track (printed side up); between the slot and one of the track rails is the best spot. In this position, it will allow the ground effects magnets on the cars to pass over them. The sensor will provide a voltage of about 3V when a car passes over it and about 2V without a magnetic field. Both counter circuits are identical, with dual op amp IC5 handling the signals from both sensors.

Circuit diagram:

 AFX Slot Car Lap Counter Circuit diagram

IC5a and IC5b are wired as comparators, with a 2.5V reference derived from zener diode ZD1 via the 10kO and 12kO resistors. Each time the output of IC5a goes high it clocks IC1a, a 4518 BCD counter. NAND gates IC2a & IC2b provide a carry out to the other half of IC1 for a 2-digit display. More counters may be cascaded this way to provide extra digits. The BCD outputs of IC1 drive 7-segment decoders IC3 & IC4 which drive common cathode LED displays. Push-button S1 resets the counters to 00 for both tracks for the start of a new race.

Author: Placid Talia - Copyright: Silicon Chip Electronics

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Step Up Booster Powers Eight White LEDs

Tiny white LEDs are capable of delivering ample white light without the fragility problems and costs associated with fluorescent backlights. They do pose a problem however in that their forward voltage can be as high as 4 V, precluding them being from powered directly from a single Li-Ion cell. Applications requiring more white LEDs or higher efficiency can use an LT1615 boost converter to drive a series connected array of LEDs. The high efficiency circuit (about 80%) shown here can provide a constant-current drive for up to eight LEDs. Driving eight white LEDs in series requires at least 29 V at the output and this is possible thanks to the internal 36-V, 350-mA switch in the LT1615.

The constant-current design of the circuit guarantees a steady current through all LEDs, regardless of the forward voltage differences between them. Although this circuit was designed to operate from a single Li-Ion battery (2.5V to 4.5V), the LT1615 is also capable of operating from inputs as low as 1 V with relevant output power reductions. The Motorola MBR0520 surface mount Schottky diode (0.5 A 20 V) is a good choice for D1 if the output voltage does not exceed 20 V. In this application however, it is better to use a diode that can withstand higher voltages like the MBR0540 (0.5 A, 40 V). Schottky diodes, with their low forward voltage drop and fast switching speed, are the best match.

Many different manufacturers make equivalent parts, but make sure that the component is rated to handle at least 0.35 A. Inductor L1, a 4.7-µH choke, is available from Murata, Sumida, Coilcraft, etc. In order to maintain the constant off-time (0.4 ms) control scheme of the LT1615, the on-chip power switch is turned off only after the 350-mA (or 100-mA for the LT1615-1) current limit is reached. There is a 100-ns delay between the time when the current limit is reached and when the switch actually turns off. During this delay, the inductor current exceeds the current limit by a small amount. This current overshoot can be beneficial as it helps increase the amount of available output current for smaller inductor values.

This will be the peak current passed by the inductor (and the diode) during normal operation. Although it is internally current-limited to 350mA, the power switch of the LT1615 can handle larger currents without problems, but the overall efficiency will suffer. Best results will be obtained when IPEAK is kept well below 700mA for the LT1615.The LT1615 uses a constant off-time control scheme to provide high efficiencies over a wide range of output current. The LT1615 also contains circuitry to provide protection during start-up and under short-circuit conditions.

When the FB pin voltage is at less than approximately 600 mV, the switch off-time is increased to 1.5 ms and the current limit is reduced to around 250 mA (i.e., 70% of its normal value). This reduces the average inductor current and helps minimize the power dissipation in the LT1615 power switch and in the external inductor L1 and diode D1. The output current is determined by Vref/R1, in this case, 1.23V/68 = 18 mA). Further information on the LT1615 may be found in the device datasheets which may be downloaded from www.linear-tech.com/pdf/16151fa.pdf

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Five band graphic equalizer

This is a five band graphic equalizer circuit. Comparatively this is a very simple diagram and working voltage is 8 volts. However you can supply up to 15 volts, but we do not recommend that much of supply. The specialty of this circuit is it operates by eighteen pins of a single chip IC ( BA 3812L ). The other components are very less.

The five frequency bands are 100Hz , 300Hz, 1kHz, 3kHz, 10kHz . You can use this simple equalizer with Hi Fi amplification systems as it provide low noise, wide dynamic range and very low distortion. If you want you can use two ICs of BA 3812L and make 10 band graphic equalizer.

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Usb Power Socket Circuit Diagram

Today, almost all computers contain logic blocks for implementing a USB port. A USB port, in practice, is capable of delivering more than 100 mA of continuous current at 5V to the peripherals that are connected to the bus. So a USB port can be used, without any trouble, for powering 5V DC operated tiny electronic gadgets. Nowadays, many handheld devices (for instance, portable reading lamps) utilise this facility of the USB port to recharge their built-in battery pack with the help of an internal circuitry.Usually 5V DC, 100mA current is required to satisfy the input power demand. Fig. 1 shows the circuit of a versatile USB power socket that safely converts the 12V battery voltage into stable 5V.

Circuit diagram:

Fig. 1: Circuit of USB power socket

This circuit makes it possible to power/recharge any USB power-operated device, using in-dash board cigar lighter socket of your car. The DC supply available from the cigar lighter socket is fed to an adjustable, three-pin regulator LM317L (IC1). Capacitor C1 buffers any disorder in the input supply.Resistors R1 and R2 regulate the output of IC1 to steady 5V, which is available at the ‘A’ type female USB socket.

Red LED1 indicates the output status and zener diode ZD1 acts as a protector against high voltage. Assemble the circuit on a general-purpose PCB and enclose in a slim plastic cabinet along with the indicator and USB socket. While wiring the USB outlet, ensure correct polarity of the supply. For interconnection between the cigar plug pin and the device, use a long coil cord as shown in Fig. 2. Pin configuration of LM317L is shown in Fig. 3.

Author : T.K. Hareendran - Source : EFY Mag

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Fuse Box BMW 540i 1993 Diagram

Fuse Box BMW 540i 1993 Diagram - Here are new post for Fuse Box BMW 540i 1993 Diagram.

Fuse Box BMW 540i 1993 Diagram

Fuse Panel Layout Diagram Parts: blower relay, crash control module, late production, auxiliary water pump relay, horn relay, jumper plug horn telephone, starter relay, compressor control relay, washer pump relay, hazard flasher relay, unloader relay, check control module, lamp control module

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Build a 10 Amp Solar Charge Controller SCC2 Circuit

The SCC2 is a solar charge controller, it’s function is to regulate the power flowing from a photovoltaic panel into a rechargeable battery. It features easy setup with one potentiometer for the float voltage adjustment, an equalize function for periodic overcharging, and automatic temperature compensation for better charging over a range of temperatures.

10 Amp Solar Charge Controller Circuit Diagram With Parts List

The goal of the circuit design was to make a charge controller with analog simplicity, high efficiency, and reliability. A medium power solar system can be built with a 12V solar panel up to 10 amps, the SCC2, and a lead acid or other rechargeable up to a few hundred amp hour capacity. The SCC2 can be operated at battery voltages other than 12V, it can work at 6V and 24V by changing a few parts. Operation at voltages between 6V and 24V is also possible.

Specifications

Maximum solar panel current: 10 Amps
Night time battery drain current: approximately 1ma
Nominal battery voltage: 6V, 12V or 24V.

Theory

The SCC2 acts as a medium power DC current switch between the + terminals of the PV and battery. Diode D1 prevents reverse night time current flow from the battery back to the PV panel.

When the PV voltage is high enough to charge the battery, zener diode D2 conducts and turns on transistor Q2. Q2 switches the power for the rest of the circuit on. The circuit is switched off at night. IC2 provides a 5 volt regulated voltage to power the comparator circuits, it also provides a reference voltage for comparator IC1a.

When the battery voltage is below the desired full voltage and needs charging, comparator IC1a turns on and activates Q1 and Q3, this allows the solar charging current to flow into the battery. Note that Q3 is a P-channel mosfet, this allows the circuit to be wired with a common ground for the solar panel and battery. The solar current loop is drawn in heavy lines on the schematic.

When the battery reaches the full charge point, IC1a operates as a comparator based schmidt trigger oscillator, it switches the solar current off and on. The switching causes the battery voltage to oscillate a few tens of millivolts above and below the desired set point. A rail-to-rail op-amp is required for proper operation, 741 style op-amps will not work in this circuit.

The red/green charging/full LED is driven between the output of IC1a and IC1b. IC1b has an inverted version of the IC1a signal. Pin 5 of IC1b only needs an approximate center point to work as an on-off comparator, it is connected to the varying IC1a pin 2 so that it does not require another reference divider circuit.

The resistors and thermistor on the input side of IC1a form a resistive bridge circuit that is used to compare the battery voltage to a reference voltage coming from IC2/R8/R9. The potentiometer adjusts the voltage point around which the circuit will oscillate on full charge. Resistor R7 adds positive feedback to IC1a for a schmidt trigger characteristic. The thermistor provides thermal compensation, as the temperature goes down, the full voltage goes up.

The equalize switch, S1a, forces the circuit on for intentional overcharging. Switch S1b and R1 can be used to select a different float voltage range, you can experiment with this by using different values of R1, typically R1 should be greater than 1M.

Alignment

    Start with a charged battery, connect the solar panel directly to the
    battery until the battery voltage is at or above the desired full setting,
    this also that the panel is capable of charging the battery.
    While measuring the battery voltage, adjust VR1 clockwise to align the
    float voltage set point.  If the LED turns red before it reaches the
    desired float voltage, the battery will need to charge for a while.
    When the battery is fully charged, it should be at the float voltage and
    the led should show alternating colors.

    The float voltage should be set when the board and battery are at room
    temperature. Typical 12V set points are 13.8V for a gell cell and 14.5V
    for a wet cell.  For 6V, divide those by two, for 24V, multiply by 2.
    Follow your battery manufacturers recommendations for the best settings.
    Readjust the float voltage after the battery has reached a full charge.The float voltage should be set when the circuit is at room temperature.

Use

Connect the solar panel to the SCC2 solar panel input connectors, connect the battery to the SCC2 output connectors. Put the solar panel in the sun, and watch the battery charge up. Systems where the battery is frequently discharged way down should occasionally be run in equalize mode for a few hours or a full day. It is best to monitor the battery voltage during this operation, disable equalization if the battery voltage goes above 16V (12V version).

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Wireless IR Headphone Transmitter

Audio input from PL1 frequency modulates the VCO section of a 4046 PLL chip. The VCO output drives Q1, a switching transistor. Q1 drives two IR LEDs. The signal produced is around 100 kHz, FM carrier VCO sensitivity is around 7.5 kHz/V.

Wireless IR Headphone Transmitter Circuit Schematic

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Controlling A Relay With A Digital Logic Level Circuit

Description 

The schematic below illustrates 4 methods of controlling a relay with a digital logic signal. Figure (A) can probably be used in most cases where the relay coil requires 100 mA or less and the input current is 2 milliamps or more. The resistor value (R) is determined from the input voltage and the available current. For example, a 5 volt input signal supplying 2 milliamps would require (5-.7)/.002 = 2150 ohms, or a 2.2K standard value. If the transistor has a minimum current gain of 50, there will be 100 mA of current available for the relay coil. The following table shows various resistor values that can be used to obtain various relay coil currents assuming a transistor current gain of 50 such as the 2N3053. 74XX refers to standard TTL logic, 74LSXX refers to low power TTL logic, 74HC is high speed CMOS and CD40XX is the older CMOS devices. The currents given are approximate values and may not be correct for all devices but should be close. 

Input Voltage - Input Current - Relay coil current - Standard Resistor

• 4 - 74LSXX .0004 - 20 milliamps - 8.2K
• 4 - 74XX .0008 - 40 milliamps - 4.3K
• 4 - 74SXX .001 - 50 milliamps - 3.3K
• 5 - 74HCXX .004 - 200 milliamps - 1K
• 6 - 74HCXX .004 - 200 milliamps - 1.3K
• 5 - CD40XX .0003 - 15 milliamps - 13K
• 12 - CD40XX .0006 - 30 milliamps - 18K

Figure B can be used when the input voltage is the same as the relay coil voltage. The voltage on the emitter of the transistor will be about 0.7 volts less than the input, so a 12 volt relay would operate on 11.3 which should be close enough. No resistor is needed since the emitter follower configuration presents a high impedance at the input. The input current will be the relay coil current divided by the transistor gain. For example a 120 ohm relay coil will draw 100 mA at 12 volts and if the transistor gain is 50, the input current will be about 2 milliamps.

Figure C can be used to provide additional gain when the input current is very small. You can also use a Darlington transistor in place of the two transistors which is a better approach, but this idea works just as well when you dont have a Darlington transistor handy. The overall gain will be the product of the individual gains of the two transistors or about 2500 for two transistor with a gain of 50 each. This will enable supplying over 250 mA to the relay with only 100 microamps of input current. The R value will depend on the input voltage and current and gain of the first transistor. For example, using a 5 volt input and 100 microamp current and transistor gain of 50, the R value will be 5 minus two diode drops (5 - 1.4) divided by the input current times 50, or about (5 - 1.4) / (.0001 * 50) = about 750 ohms. So this setup can be used when controlling heavy duty relays with low power CMOS logic signals.

Figure D can be used to reverse the relay action so that it engages when the input is low and disengages when the input is high. The R value is determined the same as in Figure A. The R1 value should be high enough to ensure saturation of the first stage and low enough to saturate the second stage. For example, if a 12 volt relay coil requires 100 mA and the driving transistor gain is 50, then the base current will be 100/50= 2 mA and the R1 value must be less than 6000 ohms so that 2 mA does not drop more than the supply voltage of 12. If the first transistor gain is 50 and the input current is 100 microamps, the collector current will be 5 mA and the R1 value must be greater than 2400 ohms so that 5 mA drops the entire supply voltage of 12. So we need to select something between these two limits of 2.4K to 6K, something around 4.3K would be near the midrange.

Circuit Diagram

Source http://www.bowdenshobbycircuits.info/r_ctrl.htm

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Wiring Color Trailer Plug

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Trailer Wiring Diagrams Johnson Trailer Sales Colfax Wisconsin.

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Direction Sensor CMPS03

CMPS03 Compass Module Overview

Compass is a tool for navigation for a direction, a direction in this article referred to is the magnetic module CMPS03 Compas. Magnetic Compass Module CMPS03 often used in making robots in the contest.

Magnetic Compass Module Functions in the contest  CMPS03 usually to provide a reference where the robots are in position and lead anywhere, then the position and direction provided by the Magnetic Compass Module reference sebgai CMPS03 the next robot motion. Magnetic Compass Module uses I2C data communication lines to mirokontroler. With adalanya I2C data communication lines from this CMPS03 this module can be connected directly to a microcontroller that suport with I2C data communication channels such as AVR ATMega. Magnetic Compass Module CMPS03 require 5 V voltage with 15mA current.

CMPS03 Circuit Diagram

Because the module using I2C Magnetic Compass CMPS03 we can use 5 lines are:
VCC + 5 V on pin 1
SCL with Pull Up resistor 10 K
SDA with Pull Up resistor 10 K
Calibrate the PIN associated with micro switch 6
Ground on PIN9

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Telephone Call Recorder

Today phone has change into an essential component of our lives. It is essentially the most extensively used communique tool on the earth. Owing to its big reputation & in style use, there arises a necessity for name reporting gadgets, which find application in name cent-res, inventory broking corporations, police, offices, homes, and so on. Here they are describing a name recorder that makes use of just a few phases. But with the intention to remember its working, must first have the basic knowledge of standard phone wiring as well as a stereo plug.

In India, land-line rings essentially use RJ11 wiring, which has wireless-tip & ring. While tip is the certain wire, ring is the terrible. & together they full the cellphone circuit. In a phone line, voltage between tip & ring is around 48V DC when handset is on the cradle(idle line). In order to ring the telephone for an incoming name, a 20Hz AC current of round 90V is superimposed over the DC voltage already present in the idle line. The poor wire from the phone line goes to IN1, whereas the positive wire goes to IN2. Further, the poor wire from OUT1 & the certain wire from OUT2 are linked to the phone. All the resistors used are zero.25W carbon movie resistors & the entire capacitors used are rated for 250V .

The poor terminal of To AUX IN is linked to pin one of the crucial stereo jack while the certain terminal is hooked up to pins two and three of the stereo jack. This stereo jack, in turn, is related to the AUX IN of any documenting device, any suchs pc, audio cas-setts participant, CD participant, DVD player, and so on. Here they will be connecting it to a pc. When a call comes in, around 90V AC current at 20Hz is superimposed over the DC voltage already present within the idle line.

This current is transformed in to DC through the diodes & fed to resistor R1, which cut backs its magnitude & feeds it to LED1. The present is additional scale backd in magnitude by using the resistor R2 & fed to the suitable & left channels of the stereo jack, that are connected to the AUX IN port of a computer. Audio fileing application,can be used to file the decision. When a call is available in, needs to launch the audio documenting software and start documenting.

For phone documenting, basically connect the stereo jack to the AUX IN port of the PC. Install the Audacity audio recorder . Run the executable Audacity file. By & huge window, you'll discover a drop-down box within the top right corner. From this box, make a selection the AUX choice. Now you are ready to report any name. As soon as a name is readily available in, press the record button current within the Audacity primary window & then choose up the telephone receiver & answer the name. Press the stop button one time the decision ends. Now go to the file menu & choose the Export as WAVE choice & save the file in a desired location.

You may exchange the price of resistor R2 if you require to vary the output volume. You can use a variable resistor in collection with R2 to range the amount of the output. The recorded audio clip may additionally be edited the usage of different choices in the Audacity application. You can gather the circuit on a general-purpose PCB & enclose it in a small cupboard. Use an RJ11 connector & stereo jack for connecting the phone set & laptop (for call reporting). Phone twines can be utilized to connect to the telephone line & the circuit. Use of a shielded cable is beneficial to reduce disturbances in the fileing. These will also be scale backd by way of growing the price of R2 to about 15 kilo-ohms.

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Battery charger using LM350

This is very useful circuit for the vehicle owners.Because most of time they have to bring their heavy 12v battery hear and there.now you dont want to do that.because you can build your own 12v charger




Notes

Use a 20 to 30 V / 3A DC power supply for powering the circuit.
This circuit is not possible for charging GEL type batteries as it draw large amounts of current.

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Green USB switch

According to the Energy Saving  Trust, if you add up all the current drawn in standby mode by items such as stereos, TVs, VCRs and DVDs over a year in the UK alone, it amounts to 3.1 million tonnes of CO2 released into the atmosphere.This is without factoring in the current drawn by all the PCs,laptops and their associated peripherals left in standby mode. 

Circuit diagram :

Green USB switch Circuit Diagram

It  is  not  necessary  to  spend  a  great deal of money or time to  make a difference on a personal  level. The circuit described here  is designed for use by laptop or  notebook computers. It will automatically switch off all mains  powered peripheral equipment  including monitor, printer, scanner, TV tuner and USB hub etc  when it detects that the notebook  is switched off. The circuit is quite  straightforward; in addition to an  optocoupler it requires a 12 V  double-pole  relay  with  mains  rated contacts and a small power  supply  for  the  optocoupler.  When the laptop is switched on  5 V appears at the USB socket,  activating the relay and switching  through  the  mains  supply  on K3 and K4. The notebook’s  USB socket is still available to be  used as normal but it’s worth remembering that the optocoupler  takes a few milliamps from the  USB supply and this may cause a  problem if a high-current device  is plugged into the USB socket.  In the case where the laptop has  more than enough USB sockets it may be worthwhile us-ing one of them solely for this  circuit, the extension USB connector K2 would then not be  required. 

The circuit is mounted into a  mains plug enclosure which  provides a socket where the  mains extension strip will be  plugged into. With any luck  there will be sufficient space  to fit the entire circuit into the  mains extension strip enclosure and save the need for a  separate enclosure. The slow-blow 6.3-A fuse (F1) protects  the equipment plugged into  the strip. 

In  addition  to  the  optocoupler  and relay the circuit also has a  ‘freewheel’ diode D1 and a relay  driver formed by T1 and its base  bias voltage divider network R2/ R4. The two ‘snubber’ networks  C1/R3 and C2/R5 reduce the  possibility of arcing which can  occur  when  the  relay  contacts  open (especially with inductive  loads). Capacitors C1 and C2  must be class X2 types which  can handle mains voltage plus any  spikes.  The  power  supply  consists of a small mains trans-former  (12 V,  50 mA),  bridge  rectifier and smoothing capacitor C3. 

The laptop’s mains adaptor itself  can also be switched by this circuit when the laptop is fitted with  its rechargeable battery which  allows the computer to boot up  without a mains supply. The en-tire USB switch circuit draws cur-rent even when it is off but this value  is  tiny  compared  to  the  combined standby current of all  the peripherals. 

Note that parts of this circuit are  connected to the (potentially lethal) mains supply voltage; it is  essential to provide protection  to ensure that nothing can accidentally make contact with these  parts of the circuit. It is also important to observe correct separation between parts of the circuit carrying low voltage and  those carrying the high volt-age. Please observe the electrical Electrical Safety guide-lines which are reprinted in  Elektor  Electronics  several  times a year. 

The  circuit  is  less  suitable  for use with desktop PCs be-cause  the  majority  of  these  machines supply 5 V over the  USB socket even though they  have been shut down via soft-ware. The only way to turn off  in this case is to reach around  the back of the machine and  switch off at the main switch. 

http://streampowers.blogspot.com/2012/06/green-usb-switch.html

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