Friday, April 22, 2011
12V DC Fan Speed Controller Using LM2941
The circuit diagram shown here is of 12V DC fan speed controller using the IC LM2941CT which is a low drop out 1A voltage regulator. The IC has a dropout voltage as low as 0.5 and has also many useful features like power supply reverse protection, thermal protection, short circuit protection etc. The maximum output current the IC can source is 1A.
The 12V DC supply is connected between the Vin (pin4) and ground (pin3) of the IC. The load, which is the fan, is connected across the Vout (pin5) and ground (pin3) of the IC. The network comprising of potentiometers R1, R2 and resistor determines adjust current (Iadj) of the IC. By varying the Iadj using the POT R2 we can adjust the output voltage of the IC and hence the fan speed.
Voice Record and Playback Circuit Using IC ISD1020A
This voice or sound recorder/playback built with IC ISD1012, ISD1016 and ISD1020 which are produced by ISD and allow sound voice recording and play-back. The last 2 digits show the maximum legth of recording time in seconds. this chip has many features like automatic gain control, anti aliasing filter, built in audio amplifier and smoothing filter. The IC is fully compatible to microprocessors and can be used for a myriad of applications. The voice is stored in their natural form in the non-volatile memory cells inside the IC which enables a high quality reproduction. T
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| Voice Record and Playback Circuit Using IC ISD1020A |
The circuit is designed as per the application diagram in the datasheet. Pin23(CE) is the chip enable pin and it has to be held low using switch in order to perform a record or playback cycle. Pin 27 (P/R) is the playback/record pin and a high level on it selects a playback cycle while a low level on it selects a record cycle. The selection can be done using the switch S3.The pin 24 (PD) is the power down pin. It has to be held high using switch S2 in order to pull the device to a extremely low power mode while there is no recording or playback (idle state).The resistor R1 and capacitor C1 determines the release time of the internal AGC circuit. The resistor R5 and capacitor C5 connected across the pin 20 and pin 21 provides an additional cut-off to the low frequency end of the voice pass band.
Sound Pressure Level Meter Circuit Using Op-Amp CA3140
This circuit is to setup home-cinema set adjusting all the loudspeaker outputs to the same level when heard from the listening position.In practice this device is a simple (though linear and precise) 100µAac millivoltmeter.
The precision of the measure is entirely depending on the frequency response of the microphone used but, fortunately, for the main purpose of this circuit an absolutely flat response is not required. Therefore, a cheap miniature electret microphone can be used.
The circuit is based on non- inverting amplifier based on op-amp CA3140 (IC1).The sound picked by the condenser mic will be amplified by the IC1 and rectified by the bridge D1 to drive the meter M1.The deflection on the meter will be proportional to the pressure of the sound falling on the mic.The switch S1 can be used as an ON/OFF switch.
Guitar Pre-amp Using Op-Amp 741
Here is A pre-amp circuit for high impedance type electric guitar pickups. The circuit is given based on a uA741 operational amplifier. The ua741 is connected as a non-inverting amplifier. The POT R1 can be used as a volume knob controller.The R6 can be used as a controller. The switch S1 is used to produce "bright" or "soft" sound effects.
Note:
- The Pre-amp Circuit can be powered from a 12V battery or 12V DC power supply.
- Up to 24 V DC can be used to power the circuit.
Tuesday, April 12, 2011
220VAC Phase Controller Circuit Using U208B
This phase control circuit can be used for controlling the power supplied to an AC load. AC waveform is controlled by the phase control circuit, cutting cycle to provide full cycle, half cycle, the cycle to zero, or somewhere in between. Maybe you can tell which is very similar to an dimmer circuit, but switching and zero crossing of the waveform is synchronized.
Triacs not to suffer power losses, thus increasing overall efficiency, there is the advantage of the power of the method of zero crossing. This control circuit is adapted phase for heating the filaments, brushed AC motor, or incandescent lamps. U208B acts as a phase control circuit in bipolar technology with monitoring of the power supply internally. Uncontrolled output pulses avoided by internal controls, tension builds. Further more, it has the sync voltage and internal power. It is strongly recommended as an inexpensive control in open loop.
Bass Treble Baxandall Tone Control circuit
This bass and treble tone controller circuit is based on the classic Baxandall tone control circuitry and provides a maximum cut and boost of around 15dB at 10kHz and 100Hz. Since the Baxandall tone control circuit is a passive design, all frequencies are amplified. The position of the bass and treble control potentiometers and reactance of the capacitors affect the audio response.
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| Bass Treble Baxandall Tone Control Circuit |
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| CA3140 Single Op-Amp PinOut |
The circuit up there is very popular Baxandall tone control configuration circuit. This Baxandall tone control has unity gain (gain=1) at midband and uses standard linear potentiometers. Low value, low cost, and small size capacitors is possible to apply because of the very high input impedance of CA3140. The frequency point is set at 100Hz and 10KHz by 15dB bass treble boost and cut. Full peak to peak output is available event at 20KHz because of excellent high slew rate characteristic of this opamp. The gain of this amplifier is decreased -3dB from flat response at 70KHz, and it’s beyond audible frequency range to make sure this tone control circuit handle the audio range perfectly.
Frequency Waveform Generator Circuit By MAX038
This circuit very useful to use waveform generator in electronic experiment and design. Using this circuit you can produce sine wave oscillation. Beside sine wave oscillation, you can also produce triangle or square wave function.
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| Frequency Waveform Generator Circuit By MAX038 |
The MAX038 is at the heart of the waveform generator circuit. complementary function is given by the IC to build a generator waveform / function generator. To build a generator circuit complete waveform, you can give some modification like change the inputs of A0 and A1 to generate the other type of wave. Put A0=X and A1=1, you will generate sine wave using this circuit. Change both A0 and A1 into 0 will produce square wave nad if you put A0=1 and A1=1, you will get triangle wave. Using current, you can control the frequency. You can control the frequency using microcontroller or digital interface if you disconnect the 20K RIN from REF (pin 1) and connect it to a DAC. By controlling the current using a phase comparator output that compares the sync output (pin 14 of MAX038) and a reference clock from quartz crystal oscillator, you can even control the chip using a quartz crystal (PLL). Since this frequency generator can generates very wide operating frequency (0.1 Hz to 20MHz), it’s become very interesting.
220VAC Motor Speed Controller Circuit With Triac
This 220VAC motor speed controller Circuit can handle brushed AC motors and other loads up to about 250W.It works the same was a dimmer circuit, cutting a portion of the AC waveform is seeking to effectively control the tension. Because of this feature will work cycle for a wide variety of loads including incandescent bulbs, heaters, brushed AC motors and transformers. The circuit attempts to maintain a constant engine speed regardless of load, it is also ideal for power tools. Note that the circuit can only control brushed AC motors. Inductive motors require a variable frequency control.
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| 220VAC Motor Speed Controller Circuit With Triac |
Note:
List Component- TR1 must be chosen to match the requirements of the load. Most generic TRIACs with ratings to support your load will work fine in this circuit.
- U1 must be chosen to match the ratings of TR1. Most generic DIAC based opto-isolators will work fine
- T1 is any small transformer with a 1:10 turns ratio. The circuit is designed to run on 120V so a 120V to 12V transformer will work. Alternately, you can wind T1 on a transformer core using a primary of 25 turns, a secondary of 200 turns, and 26 gauge magnet wire.
- R9 is used to adjust motor speed. R10 is a trim pot used to fine tune the governing action of the circuit. R8 fine tunes the feedback circuit to adjust for proper voltage at the gate of SCR1. It should be adjusted to just past the minimum point at which the circuit begins to operate.
- R13 must be chosen to match the load. Generally, larger loads will require a smaller value.
R1 : 27K 1W Resistor
R2 : 10K 1/4W Resistor
R3 : 100K 1/4W Resistor
R4 : 33K 1/4W Resistor
R5 : 2.2K 1/4W Resistor
R6 : 1K 1/4W Resistor
R7 : 60K 1/4W Resistor
R8 : 3K Trim Pot
R9 : 5K Taper Pot
R10 : 4.7K Trim Pot
R11 : 3.3K 1/4W Resistor
R12 : 100 Ohm 1/4W Resistor
R13 : 47 Ohm 1W Resistor (See Notes)
C1,C3 : 0.1uF Ceramic Capacitor
C2 : 100uF/50V
D1 : 6V Zener Diode
Q1 : 2N2222
SCR1 : ECG5400
TR1 : TRIAC (See Notes)
U1 : DIAC Opto-Isolator (See Notes)
BR1,BR2 : 5A Bridge Rectifier
T1 : Transformer (See Notes)
Automatic 12V Car Battery Charger Circuit
This car battery charger circuit is drawn to charge 12V batteries ONLY. It is fully automatic and will charge at a rate up to about 4A until the battery voltage reaches a preset point at which it will switch to a very low current float charge. If the battery voltage drops again the charger will begin charging until the voltage once again reaches the cut off point. In this way it can be left connected to a battery indefinitely to maintain full charge without causing damage.
The red LED will turn on, when charging is complete and charging circuit will deactivated. This circuit used only for 12 V battery. When wiring up the circuit, Certain emphasis should be taken. They are hose supplying current to the battery being charged and the connections of the transformer to the circuit board. To prevent heat build-up and voltage-drop when current flows through the circuit, the connections of the transformer to the circuit board should be made with cables having a large cross-sectional area
List Component:
R1= 1Kohms D1 = 1N4001 T1 = 15V/5A Transformer
R2= 1.2Kohms D2 = 6.8V 0.5W zener LD1= Green LED
R3= 470 ohms TR1= 4.7Kohms trimmer LD2= Red LED
R4= 470 ohms Q1 = BTY79/similar 6A SCR M1 = 5A DC Ampere meter
R5= 10K ohms Q2 = C106D SCR S1 = On-Off Switch
C1= 10uF/25V GR1= 6A Bridge Rectifier F = 5A Fuse
Overvoltage Protector Circuit for 12VDC
A 12VDC overvoltage protector circuit is shown in the schematic diagram below. This circuit will work to disconnect the protected device from the power supply when an overvoltage occurs at the supply. This circuit uses a silicon-controlled rectifier (SCR) and normally-closed 12-V relay, K1. The silicon-controlled rectifier is connected in parallel to 12-V line to monitor for the overvoltage condition. This applied signal is sensed by the SCR’s gate.
Until the voltage drops below the set value, the K1′s contacts remain closed and SCR1 remains off. The SCR1 will be triggered causing K1′s contacts open and halt current flow to the loas when overvoltage occurs. You can use R1 to set the trigger point of SCR1
Until the voltage drops below the set value, the K1′s contacts remain closed and SCR1 remains off. The SCR1 will be triggered causing K1′s contacts open and halt current flow to the loas when overvoltage occurs. You can use R1 to set the trigger point of SCR1
Tuesday, April 5, 2011
TL497A Simple Voltage Converter Circuit
This voltage converter circuit is built with TL497A and converts an input voltage of 5 to 12 voltage to a higher level of 15 - 30 volts. This is specially helpfull in mobile applications where power supply levels are commonly limited to 12 volts supplied by batteries.
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| TL497A Simple Voltage Converter Circuit |
Sunday, April 3, 2011
20A Variable Power Supplay Circuit Based L200 IC
This Power Supplay circuit is constructed for the use with 100Watt transceivers. When you build the unit you should care for a good kooling of the finals. The next thing is to provide at least 2500uF pro Ampere you want to pull out of it. You can get more current out of the circuit by adding more final transistors to it. Except of the emitter resistors all of the other ones are for 0,5 Watts typs.
20A Variable Power Supplay CircuitThe L200 is abel of regulating the voltage as well as the current. The TAG 226 and the zener-diode are there to protect the attached equipment against overvoltage. The power-supply is adjusted to run at 13.8V and the zener-diode is a 14V type, so as soon as the voltage gets to 14V the thyristor will be switched and produces a shortcut, and blows the 20A fuse. To use the circuit with this handbrake at higher voltages you should replace ZD14 against a higher one. Or make an adjustible krowbar that runs simultanuesly with the voltage
This power Supplay Circuit From http://www.mydarc.de/dl5dbm/20a_e.pdf
This power Supplay Circuit From http://www.mydarc.de/dl5dbm/20a_e.pdf
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