Showing posts with label low. Show all posts
Showing posts with label low. Show all posts
Wednesday, October 29, 2014
Low voltage DC motor speed control circuit using TDA7274
Low voltage DC motor speed control circuit using TDA7274
Description.
Here is the circuit diagram of a low voltage /low power DC motor speed controller based on the IC TDA 7274 from ST Microelectronics. The IC TDA 7274 is a monolithic integrated DC motor speed controller intended for low voltage/ low power applications. Built in internal voltage reference voltage, wide input voltage range (1.8 t0 6V), high linearity, 700mA output current, excellent temperature stability etc make this IC well suitable for almost all low power DC motor speed control applications.
The motor to be controlled is connected between pin3 (Vs) and pin4 (output) of the IC. Resistor network comprising of R1, R2, and R3 is the section that deals with the speed control. Control pin (pin8) of the IC is connected to the junction of R2 and R3 and the speed of the motor varies linearly according to the position of POT R3. Capacitor C1 rectifies the fluctuations in motor speed and capacitor C2 cancels the motor spikes.
Here is the circuit diagram of a low voltage /low power DC motor speed controller based on the IC TDA 7274 from ST Microelectronics. The IC TDA 7274 is a monolithic integrated DC motor speed controller intended for low voltage/ low power applications. Built in internal voltage reference voltage, wide input voltage range (1.8 t0 6V), high linearity, 700mA output current, excellent temperature stability etc make this IC well suitable for almost all low power DC motor speed control applications.
The motor to be controlled is connected between pin3 (Vs) and pin4 (output) of the IC. Resistor network comprising of R1, R2, and R3 is the section that deals with the speed control. Control pin (pin8) of the IC is connected to the junction of R2 and R3 and the speed of the motor varies linearly according to the position of POT R3. Capacitor C1 rectifies the fluctuations in motor speed and capacitor C2 cancels the motor spikes.
The circuit can be assembled on a Perf board.
Power supply Vs can be anything between 1.8V to 6V and it must be selected according to the rating s of the motor.
Maximum output current capacity of this circuit is 700mA.
TDA7274 must be mounted on a holder.
POT R3 can be used to vary the motor speed
Wednesday, October 1, 2014
High Low Voltage Protector Circuit for Refrigerator with Timer
Back up power supply can be provided to the timer circuit to maintain time cycles during power failure as shown in Fig. 2. , By using different outputs (Q0 t to Q9, not shown) of IC 4017 or IC 0 4060, the timer can be utilised for purposes such as delayed and precise switching.
Thursday, September 11, 2014
Low Power Wireless Audio Power Amplifier
Using this low-cost project one can reproduce audio from TV without disturbing others. It does not use any wire connection between TV and Loud Speaker. In place of a pair of wires, it uses invisible infra-red light to transmit audio signals from TV to Loud speakers, Without using any lens a range of up to 6 meters is possible. Range can be extended by using lenses and reflectors with IR sensors comprising transmitters and receivers.
IR transmitter uses two-stage transistor amplifier to drive two series-connected IR LEDs. An audio output transformer (T1) is used (in reverse) to couple audio output from TV to the IR transmitter. Transistors Q1 and Q2 amplify the audio signals received from TV through the audio transformer. Low impedance output windings (lower gauge or thicker wires) are used for connection to TV side while high-impedance windings are connected to IR transmitter. This IR transmitter can be powered from a 9V mains adapter or a 9V battery. Red LED (D1) in transmitter circuit functions as a Zener diode (0.65V) as well as supply-on indicator.
Transmitter diagram:
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| Wireless Audio Power Amplifier Transmitter Circuit Diagram |
Receivers operation:
IR receiver uses popular op-amp IC µA741 and audio-frequency amplifier IC LM386 along with phototransistor L14F1 (Q3) and some discrete components. The sound generated by TV set is transmitted through IR LEDs, received by phototransistor Q3 and fed to pin 2 of IC µA741 (IC1). Its gain can be varied using potmeter P2. The output of IC µA741 is fed to IC LM386 (IC2) via capacitor (C7) and potmeter P3. The sound produced is heard through the receiver’s loudspeaker. Potmeter P3 is used to control the volume of loudspeaker SPKR (8-ohm, 1W).
Receiver diagram:
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| Wireless Audio Power Amplifier Transmitter Circuit Diagram |
Parts:
P1 = 10K
P3 = 10K
P2 = 1M
R1 = 4.7K
R2 = 22K
R3 = 100R
R4 = 10R-1W
R5 = 10K
R6 = 10K
R7 = 15K
R8 = 15K
R9 = 100K
R10 = 680R-1W
R11 = 1K
R12 = 10R-1W
C1 = 220uF-25V
C2 = 220uF-25V
C3 = 10uF-25V
C4 = 220uF-25V
C5 = 220uF-25V
C6 = 100nF-63V
C7 = 100nF-63V
C8 = 100nF-63V
C9 = 100nF-63V
D1 = Red LED
D2 = IR LEDs
D3 = IR LEDs
Q1 = BC547
Q2 = BD140
Q3 = L14F1
IC1 = uA741 Opamp
IC2 = LM386
J1 = Audio input Jack
T1 = Audio Transformer
SPKR = 1W-8ohm
Friday, September 5, 2014
build a Low Cost Stereo Level Indicator
Usually, Low-Cost Stereo Level Indicator home stereo power amplifiers don’t have output level indicators. An output power level indicator can be added to each channel of these stereo power amplifiers. As low levels of the output power are not disturbing and damaging to the people, there is no need to add a preamplifier and low-level detector before IC LM3915. But you should know when the output power becomes considerably high.
Here we present a very simple, low-cost stereo-level indicator schema for home power amplifiers with power rating of around 0.5W. The schema is built around two LM3915 dot/bar display driver ICs (IC1 and IC2). LM3915 senses analogue voltage levels to drive ten LEDs, providing a logarithmic 3dB/step analogue display.
Stereo Level Indicator Circuit Diagram
Here we present a very simple, low-cost stereo-level indicator schema for home power amplifiers with power rating of around 0.5W. The schema is built around two LM3915 dot/bar display driver ICs (IC1 and IC2). LM3915 senses analogue voltage levels to drive ten LEDs, providing a logarithmic 3dB/step analogue display.
Stereo Level Indicator Circuit Diagram
The voltage levels below 1V are not important because these correspond to a low level of the audio signal. Similarly, input voltage levels above 30V correspond to too high levels of the output power, which are not applicable for home power amplifiers. So the voltage levels of our interest are 1V to 30V, which can be handled directly with LM3915. LM3915 needs no protection against ±35V inputs, which simplifies the schema.
Most audio power amplifiers can drive 2-ohm to around 32-ohm loads. A load of several kilo-ohms will not change the conditions for the amplifier. CON1 is the input connector and CON2 output connector for the loudspeaker or headphone. Each channel has its own LM3915 and ten LEDs to indicate the power level. To indicate the different audio levels, select LEDs of three colours as per your liking. For example, you can have five green LEDs, three yellow LEDs and two red LEDs.
If appropriate signal generators and measuring equipment are not available, the level indicator can be calibrated based on personal observations. For example, the audio signal should be in the green LEDs zone when the signal is strong enough but not irritating, in the yellow zone when it is disturbing or starting to get distorted, and in the red zone when it is heavily distorted or too strong to listen to in the room.
Calibration can be done with the help of potentiometers VR1 and VR2, which are optional. Switches S1 and S2 let you select between two modes of LM3915 operation—the bar mode and the dot mode. These too can be removed or replaced with jumpers, if not required. When the switches are removed, leave pins 9 of IC1 and IC2 open.
The schema works off regulated 12V. You can also power it through a 12V rechargeable battery.
Assemble the schema on a general-purpose PCB and enclose in a suitable cabinet. Fix all the LEDs in two rows on the front side of the cabinet. Also affix the two terminals for input and output on rear side of the cabinet. link
Most audio power amplifiers can drive 2-ohm to around 32-ohm loads. A load of several kilo-ohms will not change the conditions for the amplifier. CON1 is the input connector and CON2 output connector for the loudspeaker or headphone. Each channel has its own LM3915 and ten LEDs to indicate the power level. To indicate the different audio levels, select LEDs of three colours as per your liking. For example, you can have five green LEDs, three yellow LEDs and two red LEDs.
If appropriate signal generators and measuring equipment are not available, the level indicator can be calibrated based on personal observations. For example, the audio signal should be in the green LEDs zone when the signal is strong enough but not irritating, in the yellow zone when it is disturbing or starting to get distorted, and in the red zone when it is heavily distorted or too strong to listen to in the room.
Calibration can be done with the help of potentiometers VR1 and VR2, which are optional. Switches S1 and S2 let you select between two modes of LM3915 operation—the bar mode and the dot mode. These too can be removed or replaced with jumpers, if not required. When the switches are removed, leave pins 9 of IC1 and IC2 open.
The schema works off regulated 12V. You can also power it through a 12V rechargeable battery.
Assemble the schema on a general-purpose PCB and enclose in a suitable cabinet. Fix all the LEDs in two rows on the front side of the cabinet. Also affix the two terminals for input and output on rear side of the cabinet. link
Thursday, September 4, 2014
Low voltage audio amplifier circuit from 0 9 volts
Here i share power amplifier based on IC TDA7236 . This amplifier require minimum voltage 0,9 volt and maximum voltage is 1, 6 volt , its very low voltage amplifier. You can use this amplifier everywhere just with one battery 1,5 volt. Power output 16 mW with 32 ohms impedance. see circut below :
Tuesday, September 2, 2014
Low Dropout Adjustable Regulator Circuit
Low Dropout Adjustable Regulator Circuit
We frequently acquire requests for voltage regulators for systems for which the accepted LM317 is not suitable. Although the LM317 can acquire ascribe voltages up to 3-40 Volts, and achievement adapted voltages from 1.2-37 Volts, it can alone achievement a reliable anchored voltage if the ascribe voltage is at atomic 2-3 Volts college than the called achievement voltage - e.g. to get a reliable 12.0V output, the ascribe voltage would charge to be 15V+. This voltage aberration is the dropout, the bulk of voltage alone (dissipated/wasted as heat) in the regulator.
Low Dropout Anchored Voltage Regulators
Where a anchored voltage regulator is required, article like the LM2940 ambit can be used. These are low dropout voltage regulators about accessible with anchored achievement voltages of 5, 10, 12, and 15 Volts.
Such a regulator is complete for use for archetype area 12V rated LED spotlights are to be powered with a 12V battery. The array voltage can ambit from 12.5 to 14+ Volts, and we charge a anchored 12.0V to ability the LEDs, so although an LM317 would not be reliable, the LM2940 (which will bead no added than 0.5 Volts) would accord a anchored 12.0V achievement beyond the abounding voltage ambit of the array reliably.
Unfortunatately we cannot use an LM2940 area a non-standard voltage - e.g. 8.50 Volts - is required. Ideally we appetite article with the adaptability of the LM317, but the low dropout characteristics of the LM2950. Fortunately such a basic exists and it is the LM2941 adjustable low bead out voltage regulator (which is pictured above).
The LM2941 can achievement voltages from 5.0 to 15.0 Volts * with a archetypal dropout voltage of aloof 0.5 Volts (@ 1 Amp, beneath for lower currents), and an complete best dropout of 1.0 Volts beyond the abounding temperature range. The LM2941 can accumulation up to 1 Amp of current.
* Note that the best ascribe voltage is 26 Volts, so this basic is not acceptable for 24 Volt rated systems.
Pictured aloft is the archetypal appliance ambit application the LM2941 as an adjustable voltage regulator. The advertence voltage (measured beyond ADJ and GND) is 1.275V. With the resistor R1 about set to 1K, the amount of R2 for any accustomed adapted achievement voltage is affected application the afterward equation:
R2 = R1 (( Vout / Vref) - 1 ))
For example, if an 8.00V low voltage bead out regulator is required, R1 = 1K, Vref = 1.275, and so R2 = 1000((8.00/1.275) - 1) = 5276 Ohms.
Turning the blueprint about we can additionally account the achievement voltage for any accustomed ethics of R1 and R2:
Vout = Vref * ((R1 + R2) / R1)
...so if we accumulate R1 as 1K and set R1 as 5K1 (since the 5276 Ohm amount affected is acutely not a accepted resistor) we see that Vout = 1.275 ((1000 + 5100) / 1000) = 7.78 Volts. (Note that it is accessible to affix accepted resistors in alternation abacus up their ethics to get an exact amount if a actual authentic voltage regulator is appropriate - e.g. 4K7 + 560R + 10R + 5R6 = 5276 Ohms for an 8.00V regulator)
Click actuality to appearance the LM2941 Datasheet (PDF) with sample diagram, and abundant blueprint data.
Low Dropout Anchored Voltage Regulators
Where a anchored voltage regulator is required, article like the LM2940 ambit can be used. These are low dropout voltage regulators about accessible with anchored achievement voltages of 5, 10, 12, and 15 Volts.
Such a regulator is complete for use for archetype area 12V rated LED spotlights are to be powered with a 12V battery. The array voltage can ambit from 12.5 to 14+ Volts, and we charge a anchored 12.0V to ability the LEDs, so although an LM317 would not be reliable, the LM2940 (which will bead no added than 0.5 Volts) would accord a anchored 12.0V achievement beyond the abounding voltage ambit of the array reliably.
Unfortunatately we cannot use an LM2940 area a non-standard voltage - e.g. 8.50 Volts - is required. Ideally we appetite article with the adaptability of the LM317, but the low dropout characteristics of the LM2950. Fortunately such a basic exists and it is the LM2941 adjustable low bead out voltage regulator (which is pictured above).
The LM2941 can achievement voltages from 5.0 to 15.0 Volts * with a archetypal dropout voltage of aloof 0.5 Volts (@ 1 Amp, beneath for lower currents), and an complete best dropout of 1.0 Volts beyond the abounding temperature range. The LM2941 can accumulation up to 1 Amp of current.
* Note that the best ascribe voltage is 26 Volts, so this basic is not acceptable for 24 Volt rated systems.
Pictured aloft is the archetypal appliance ambit application the LM2941 as an adjustable voltage regulator. The advertence voltage (measured beyond ADJ and GND) is 1.275V. With the resistor R1 about set to 1K, the amount of R2 for any accustomed adapted achievement voltage is affected application the afterward equation:
R2 = R1 (( Vout / Vref) - 1 ))
For example, if an 8.00V low voltage bead out regulator is required, R1 = 1K, Vref = 1.275, and so R2 = 1000((8.00/1.275) - 1) = 5276 Ohms.
Turning the blueprint about we can additionally account the achievement voltage for any accustomed ethics of R1 and R2:
Vout = Vref * ((R1 + R2) / R1)
...so if we accumulate R1 as 1K and set R1 as 5K1 (since the 5276 Ohm amount affected is acutely not a accepted resistor) we see that Vout = 1.275 ((1000 + 5100) / 1000) = 7.78 Volts. (Note that it is accessible to affix accepted resistors in alternation abacus up their ethics to get an exact amount if a actual authentic voltage regulator is appropriate - e.g. 4K7 + 560R + 10R + 5R6 = 5276 Ohms for an 8.00V regulator)
Click actuality to appearance the LM2941 Datasheet (PDF) with sample diagram, and abundant blueprint data.
Monday, August 18, 2014
Low voltage mono stereo power amplifier
GENERAL DESCRIPTION
The TDA7050T is a low voltage audio amplifier for small radios with headphones (such as watch, pen and pocket radios) in mono (bridge-tied load) or stereo applications.
Features
- Limited to battery supply application only (typ. 3 and 4 V)
- Operates with supply voltage down to 1,6 V
- No external components required
- Very low quiescent current
- Fixed integrated gain of 26 dB, floating differential input
- Flexibility in use − mono BTL as well as stereo
- Small dimension of encapsulation (see package design example).
Circuit Diagram
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| Circuit diagram Low voltage mono/stereo power amplifier |
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