Saturday, January 11, 2014
Simple Power Switching Circuit Diagram
This Simple Power Switching Circuit Diagram provides on/off switching, soft starting, current monitoring, current tripping, and protection against over-current for a 30 Vdc power supply at normal load currents up to 2 A. The switch is turned on by an `on` command pulse; it is turned off by an `off` command pulse. An over-current trip can also be set on the bus side by a 6-digit binary signal, which is converted to an analog voltage and compared with the amplified voltage developed across a load-current-sensing resistor.
Resistor/capacitor combinations (0.027 µ, 2 kfi) at the inputs of the current-sensing amplifiers act as low-pass filters: this introduces a few hundred /is of delay in the response to over-current, thereby providing some immunity to noise. The 0.022 µ capacitors connected to the drain terminals of the PFETs provide a Miller effect, which reduces the rate of change of the drain voltage and therefore the rate of rise of current at turn-on. The soft-turn-on time depends upon the load impedance and is typically 100 to 200 ms.
Power Switching Circuit Diagram
Friday, January 10, 2014
Lights On!
This circuit ensures that you will never again forget to switch on the lights of your car. As soon as the engine is running, the dipped beams and the sidelights are automatically switched on. The circuit also causes the dipped beams to be extinguished as soon as the main beams are switched on. As you can see from the schematic diagram, no special components are needed. When the engine is running, the alternator will generate a voltage of more than 14 V. Diode D1 reduces this voltage by 5.6 V and passes it to the base of T1 via R1. Due to the resulting current, T1 conducts. The amplified current flows via R3, the base of T3 and D3 to ground. This causes T3 to also conduct and energize relay Re1.
Lights On Circuit diagram :
If the driver now switches on the main beams, a current flows through D2 and R2 into the base of T2, causing this transistor to conduct. As a result, the voltage on the base of T3 drops, causing T3 to cut off and the relay to drop out. When the main beams are switched off, the previous situation is restored, and the relay again engages. The dipped beams and the sidelights are switched by the contacts of relay Re1. Diodes D5 and D6 ensure that the sidelights are illuminated if either the dimmed beams or the main beams are switched on. In practice, this means that the sidelights will be on whenever the engine is running, regardless of whether the main beams are switched on.
Source : www.ecircuitslab.com/2011/05/lights-on.html
Temperature Sensor Circuit Diagram
The LM35 temperature sensor provides an output of 10 mV/C for every degree Celsius over 0C. At 20C the output voltage is 20 10 = 200 mV. The circuit consumes 00. The load resistance should not be less than 5 kQ. A 4- to 20-V supply can be used.
Temperature Sensor Circuit Diagram
Thursday, January 9, 2014
Super linear FM Circuit Diagram
Designing various electronic circuit system (synthesizer, modem, decoder, data converter, etc) of ten need a frequency modulator subsystem. An FM modulator is very easy to build with TC9400 since the it has very good linearity as V/F converter. While Vin determines the amount of modulation (FM deviation) around the center frequency, the potentiometer determines the center frequency. Vin can be negative as well as positive.
Superlinear FM Circuit Diagram
Superlinear FM Circuit Diagram
Portable Solar Lamp Lantern
This portable solar lantern circuit uses 6 volt/5 watt solar panels are now widely available. With the help of such a photo-voltaic panel we can construct an economical, simple but efficient and truly portable solar lantern unit. Next important component required is a high power (1watt) white LED module.
When solar panel is well exposed to sunlight, about 9 volt dc available from the panel can be used to recharge a 4.8 volt /600mAh rated Ni-Cd battery pack. Here red LED (D2) functions as a charging process indicator with the help of resistor R1. Resistor R2 regulates the charging current flow to near 150mA.
Solar Lantern Circuit Schematic
Assuming a 4-5 hour sunlit day, the solar panel (150mA current set by the charge controller resistor R2) will pump about 600 – 750 mAh into the battery pack. When power switch S1 is turned on, dc supply from the Ni-Cd battery pack is extended to the white LED (D3). Resistor R3 determines the LED current. Capacitor C1 works as a buffer.
Note: After construction, slightly change the values of R1,R2 and R3 up/down by trial&error method, if necessary.
See More Detail[...]
When solar panel is well exposed to sunlight, about 9 volt dc available from the panel can be used to recharge a 4.8 volt /600mAh rated Ni-Cd battery pack. Here red LED (D2) functions as a charging process indicator with the help of resistor R1. Resistor R2 regulates the charging current flow to near 150mA.
Solar Lantern Circuit Schematic
Assuming a 4-5 hour sunlit day, the solar panel (150mA current set by the charge controller resistor R2) will pump about 600 – 750 mAh into the battery pack. When power switch S1 is turned on, dc supply from the Ni-Cd battery pack is extended to the white LED (D3). Resistor R3 determines the LED current. Capacitor C1 works as a buffer.
Note: After construction, slightly change the values of R1,R2 and R3 up/down by trial&error method, if necessary.
Friday, December 27, 2013
DC 1 3V to 22V Adjustable Regulator
This compact regulator PCB can be used to produce a fully regulated DC supply ranging from 1.3V to 22V at currents up to 1A. Depending on how much current you need, it can fit into tiny spaces and is easily connected with 2-pin headers for DC input, DC output, an on/off switch and a LED. There are many fixed-voltage IC regulators available such as those with 5V, 6V 8V, 9V, 12V & 15V outputs.
But what if you want a voltage output that does not fit into one of the standard ranges or if you want to be able to easily adjust this output voltage? The MiniReg is the answer: it can be set to provide the exact voltage you require. It is based on an LM317T 3-terminal regulator. The PCB has only a few other components: three diodes, three capacitors, two resistors and a trimpot to set the output voltage from the regulator.
Diagram shows the circuit details. The LM317T adjustable regulator provides a nominal 1.25V between its OUT and ADJ (adjust) terminals. The output voltage from REG1 is set by the 110O resistor (R1) between the OUT and ADJ terminals and by the resistance between the ADJ terminal and ground. This works as follows: by using a 110O resistor and assuming an exact 1.25V reference, the current flow is set at 11.36mA. This is calculated by dividing the voltage between the OUT and ADJ terminals (1.25V) by the 110O resistor.
This current also flows through trimpot VR1. This means that if VR1 is set to a value of 1kO , then the voltage across this resistor will be 1kO x 11.36mA or 11.36V. This voltage is then added to the 1.25V reference to derive the output voltage ñ in this case 12.61V. In practice, the current flow out of the ADJ terminal also contributes slightly to the final output voltage. This current is of the order of 100µA. So if VR1 is set to 1kO , this can add 0.1V to the output, ie, we get 12.71V.
If you are interested in the output voltage equation, then it is:
VOUT = VREF(1 + R1/R2) + IADJ x R2
where VOUT is the output voltage, VREF is the voltage between the OUT and ADJ terminals and IADJ is the current out of the ADJ terminal (typically 50µA but as high as 100µA). R1 is the resistance between the OUT and ADJ terminals, while R2 is the resistance between the ADJ terminal and ground. Diode D1 in series with the input provides reverse polarity protection. This means that if you connect the supply voltage around the wrong way, you cannot do any damage.
Diode D2 protects the regulator if the input becomes shorted to ground while it is powered up. Without D2, current would attempt to flow back from the output capacitor through the regulator to the shorted input and that could kill it. But D2 becomes forward biased and conducts, effectively preventing any reverse current flow through REG1.
Diode D3 is also included to protect REG1. It does this by clamping the voltage between the ADJ terminal and the OUT & IN terminals in the event that one of the latter is shorted to ground. Finally, capacitors C1 & C2 reduce ripple and noise by bypassing the IN (input) and ADJ terminals respectively. C3 prevents regulator oscillation by swamping any low-value capacitance that may be connected to this output.
See More Detail[...]
But what if you want a voltage output that does not fit into one of the standard ranges or if you want to be able to easily adjust this output voltage? The MiniReg is the answer: it can be set to provide the exact voltage you require. It is based on an LM317T 3-terminal regulator. The PCB has only a few other components: three diodes, three capacitors, two resistors and a trimpot to set the output voltage from the regulator.
 |
| DC 1.3V to 22V Power Supply Circuit Diagram |
Diagram shows the circuit details. The LM317T adjustable regulator provides a nominal 1.25V between its OUT and ADJ (adjust) terminals. The output voltage from REG1 is set by the 110O resistor (R1) between the OUT and ADJ terminals and by the resistance between the ADJ terminal and ground. This works as follows: by using a 110O resistor and assuming an exact 1.25V reference, the current flow is set at 11.36mA. This is calculated by dividing the voltage between the OUT and ADJ terminals (1.25V) by the 110O resistor.
This current also flows through trimpot VR1. This means that if VR1 is set to a value of 1kO , then the voltage across this resistor will be 1kO x 11.36mA or 11.36V. This voltage is then added to the 1.25V reference to derive the output voltage ñ in this case 12.61V. In practice, the current flow out of the ADJ terminal also contributes slightly to the final output voltage. This current is of the order of 100µA. So if VR1 is set to 1kO , this can add 0.1V to the output, ie, we get 12.71V.
If you are interested in the output voltage equation, then it is:
VOUT = VREF(1 + R1/R2) + IADJ x R2
where VOUT is the output voltage, VREF is the voltage between the OUT and ADJ terminals and IADJ is the current out of the ADJ terminal (typically 50µA but as high as 100µA). R1 is the resistance between the OUT and ADJ terminals, while R2 is the resistance between the ADJ terminal and ground. Diode D1 in series with the input provides reverse polarity protection. This means that if you connect the supply voltage around the wrong way, you cannot do any damage.
Diode D2 protects the regulator if the input becomes shorted to ground while it is powered up. Without D2, current would attempt to flow back from the output capacitor through the regulator to the shorted input and that could kill it. But D2 becomes forward biased and conducts, effectively preventing any reverse current flow through REG1.
Diode D3 is also included to protect REG1. It does this by clamping the voltage between the ADJ terminal and the OUT & IN terminals in the event that one of the latter is shorted to ground. Finally, capacitors C1 & C2 reduce ripple and noise by bypassing the IN (input) and ADJ terminals respectively. C3 prevents regulator oscillation by swamping any low-value capacitance that may be connected to this output.
Thursday, December 26, 2013
USB Powered Audio Power Amplifier
This circuit of multimedia speakers for PCs has single-chip-based design, low-voltage power supply, compatibility with USB power, easy heat-sinking, low cost, high flexibility and wide temperature tolerance. At the heart of the circuit is IC TDA2822M. This IC is, in fact, mono-lithic type in 8-lead mini DIP package. It is intended for use as a dual audio power amplifier in battery-powered sound players. Specifications of TDA2822M are low quiescent current, low crossover distortion, supply voltage down to 1.8 volts and minimum output power of around 450 mW/channel with 4-ohm loudspeaker at 5V DC supply input.
An ideal power amplifier can be simply defined as a circuit that can deliver audio power into external loads without generating significant signal distortion and without consuming excessive quiescent current. This circuit is powered by 5V DC supply available from the USB port of the PC. When power switch S1 is flipped to ‘on’ position, 5V power supply is extended to the circuit and power-indicator red LED1 lights up instantly. Resistor R1 is a current surge limiter and capacitors C1 and C4 act as buffers. Working of the circuit is simple. Audio signals from the PC audio socket/headphone socket are fed to the amplifier circuit through components R2 and C2 (left channel), and R3 and C3 (right channel)
USB Powered Audio Power Amplifier Circuit diagram:
Potmeter VR1 works as the volume controller for left (L) channel and potmeter VR2 works for right (R) channel. Pin 7 of TDA2822M receives the left-channel sound signals and pin 6 receives the right-channel signals through VR1 and VR2, respectively. Ampl i f ied signals for driving the left and right loudspeakers are available at pins 1 and 3 of IC1, respectively. Components R5 and C8, and R6 and C10 form the traditional zobel network. Assemble the circuit on a medium-size, general-purpose PCB and enclose in a suitable cabinet. It is advisable to use a socket for IC TDA2822M. The external connections should be made using suitably screened wires for better result.
Sucre: http://www.ecircuitslab.com/2011/06/usb-powered-audio-power-amplifier.html
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