Schematic | Circuit guide | Manual Wiring diagram | Electronic

Touch Controlled Mute Switch Circuit Diagram

Posted by merzaha gulhku Friday, September 5, 2014 0 comments
Here is another simple circuit to mute the volume of Audio devices through simple touch. It exploits the action of the flip-flops in the timer IC 555 to reduce the volume of the Audio amplifier. IC NE555 is designed in the toggle mode. Its lower and upper comparator inputs are connected to the touch plates which can be membrane switches or two pieces of conducting plates. The inputs of comparators are stabilized through R1 and R2 to avoid floating.

Touch controlled Mute switch circuit diagram

 Touch Controlled Mute Switch Circuit Diagram

 
When the touch plate connected to pin 2 is touched momentarily, output of IC1 goes high and T1 conducts. The centre tap of the volume control is connected to the collector of T1. So when T1 conducts current going to the amplifier drains through T1. This reduces the volume.IC1 remains latched in this position with LED on. When the touch plate connected to pin 6 is touched momentarily, output of IC1 goes low and T1 turns off. This restores the volume.

Dual Oscillator For Microcontrollers

Posted by merzaha gulhku Saturday, January 11, 2014 0 comments
The MAX7378 contains two oscillators and a power-on reset circuit for microprocessors. The Speed input selects either 32.768 kHz (LF) or a higher frequency, which is pre-programmed. The type number corresponds to the standard pre-programmed value and the value of the reset threshold. There is a choice of two threshold values: 2.56 V and 4.29 V.

Both thresholds are available with all standard frequencies, which are 1 MHz, 1.8432 MHz, 3.39545 MHz, 3.6864 MHz, 4 MHz, 4.1943 MHz, and 8 MHz. However, any frequency between 600 kHz and 10 MHz is also possible. An internal synchronization circuit ensures that no glitches occur when switching between the two oscillators. The Reset output of the MAX7378 is available in three different options.


Two of the options are push-pull types, either active low or active high. The third option is open drain, which thus requires an external pull-up resistor. That is the only standard option (which is why a resistor in dashed outline is shown connected to the Reset output). The Reset signal remains active for 100 µs after the supply voltage rises above the threshold voltage.

The Reset signal becomes active immediately if the voltage drops below the threshold. The IC is powered via two separate pins. The VL pin powers the reset and oscillator circuitry, while the VCC pin powers the remainder of the chip. The two pins must always have the same potential. Good decoupling in the form of two 100-nF ceramic capacitors (SMD types) is also necessary.

The IC is housed in the tiny 8-pin µMAX package and has dimensions of only 3.05 × 5.03 mm including pins, with a pin pitch of only 0.65 mm. Unfortunately, the accuracy of the oscillators is not especially good. The HF oscillator has an error of ±2% at 25 °C with a 5-V supply voltage and a maximum temperature coefficient of +325 ppm, which doesn’t exactly correspond to crystal accuracy, but it is certainly usable for most non-time-critical applications.

The error over the full supply voltage range (2.7–5.5 V) is twice as large. The 32.768-kHz oscillator is more accurate, with an error of only 1% at 5 V and 25 °C, although this is still a bit too much for time measurements. The error can be as much as ±3% over the entire supply voltage range. The maximum current consumption is 5.5 mA, which is relatively low.

The battery of this kind of good cell phone jammer

Posted by merzaha gulhku Friday, January 10, 2014 0 comments
The battery of this kind of good cell phone jammer is the durable type.
Hybrid satellite and terrestrial solutions to the countries covered by geostationary satellites in low-power repeater network and the mobile base station co-location, to provide urban and indoor coverage. The manufacturers argue that, if you do not use the S-band in the country coverage of the DVB-H in UHF is not economical because it requires a large number of transmitter and receiver. The market is still before the analog shutdown mode, the lack of available digital spectrum to support deployment of this technology, at the same time, the S-band frequency bands are available in any place. Manufacturers are expected to DVB-SH will commence in Europe for land the citys commercial, the end of 2007 to 2009, there will be a dedicated satellite to provide country-wide coverage. The product description of cell phone jammer should be as exact and accurate as possible.Several shielding positions of cell phone jammer locate at sides of hallway
A variety of software in the smart phone Forum, endless domestic mobile phone software applications has just started, users do not have a strong ability to identify, the results appeared in fish, wanton rampage rogue, front-end on the occurrence of an influential and destructive strong OPDA trays "incident, in the new software, especially the OPDA smart phone Forum, users claim that a famous foreign software crack, the results of the user under the computer all automatic grid, resulting in a lot of bad impact. On the computer, the rogue software on the phone more than is deducted user fees, get money for the purpose, so the worse nature, some commercial software is self-defeating. The customer should use and maintain cell phone jammer in the suitable manner.
User pull: In Japan, mobile payment wallet alternative is obvious. Buy virtual goods online supermarket shopping and spending, take the subway, take the bus, hospitals no longer need to queue up, the airport do not have to queue up for boarding passes, dinner singing and watching movies. Almost all of the daily consumption can be by a brush easy to get. In China, after years of gestation period, the user has the convenience of mobile payment is more recognition. The market potential is huge: CUP data show that the first half of 2009, Chinas mobile payment users exceeded 19.2 million, a transaction of 62,680,000 results, the amount to be paid a total of 17 billion yuan of transactions and transaction amount increased by 42% and 64% respectively than last year.
But will have on the wireless network in seconds, this speed is too slow to run a network game. Mobile operators strive to improve the mobile phones available bandwidth, network latency has not been satisfactorily resolved.

22Watt Car Subwoofer Amplifier

Posted by merzaha gulhku 0 comments
22W into 4 Ohm power amplifier, Variable Low Pass Frequency: 70 – 150Hz

This unit is intended to be connected to an existing car stereo amplifier, adding the often required extra "punch" to the music by driving a subwoofer. As very low frequencies are omnidirectional, a single amplifier is necessary to drive this dedicated loudspeaker. The power amplifier used is a good and cheap BTL (Bridge Tied Load) 13 pin IC made by Philips (now NXP Semiconductors) requiring a very low parts count and capable of delivering about 22W into a 4 Ohm load at the standard car battery voltage of 14.4V.

22 Watt Car Subwoofer Amplifier Circuit diagram:

22 Watt Car Subwoofer Amplifier Circuit Diagram
Parts:

P1_____________10K Log Potentiometer
P2_____________22K Dual gang Linear Potentiometer
R1,R4___________1K 1/4W Resistors
R2,R3,R5,R6____10K 1/4W Resistors
R7,R8_________100K 1/4W Resistors
R9,R10,R13_____47K 1/4W Resistors
R11,R12________15K 1/4W Resistors
R14,R15,R17____47K 1/4W Resistors
R16_____________6K8 1/4W Resistor
R18_____________1K5 1/4W Resistor
C1,C2,C3,C6_____4µ7 25V Electrolytic Capacitors
C4,C5__________68nF 63V Polyester Capacitors
C7_____________33nF 63V Polyester Capacitor
C8,C9_________220µF 25V Electrolytic Capacitors
C10___________470nF 63V Polyester Capacitor
C11___________100nF 63V Polyester Capacitor
C12__________2200µF 25V Electrolytic Capacitor
D1______________LED any color and type
Q1,Q2_________BC547 45V 100mA NPN Transistors
IC1___________TL072 Dual BIFET Op-Amp
IC2_________TDA1516BQ 24W BTL Car Radio Power Amplifier IC
SW1____________DPDT toggle or slide Switch
SW2____________SPST toggle or slide Switch capable of withstanding a current of at least 3A
J1,J2__________RCA audio input sockets
SPKR___________4 Ohm Woofer or two 8 Ohm Woofers wired in parallel
The stereo signals coming from the line outputs of the car radio amplifier are mixed at the input and, after the Level Control, the signal enters the buffer IC1A and can be phase reversed by means of SW1. This control can be useful to allow the subwoofer to be in phase with the loudspeakers of the existing car radio. Then, a 12dB/octave variable frequency Low Pass filter built around IC1B, Q1 and related components follows, allowing to adjust precisely the low pass frequency from 70 to 150Hz. Q2, R17 and C9 form a simple dc voltage stabilizer for the input and filter circuitry, useful to avoid positive rail interaction from the power amplifier to low level sections.

Notes:
  • IC2 must be mounted on a suitable finned heatsink
  • Due to the long time constant set by R17 and C9 in the dc voltage stabilizer, the whole amplifier will become fully operative about 15 - 30 sec. after switch-on.
Technical data:

Output power (1KHz sinewave):
22W RMS into 4 Ohms at 14.4V supply
Sensitivity:
250mV input for full output
Frequency response:
20Hz to 70Hz -3dB with the cursor of P2 fully rotated towards R12
20Hz to 150Hz -3dB with the cursor of P2 fully rotated towards R11
Total harmonic distortion:
17W RMS: 0.5% 22W RMS: 10%

Source :  http://www.ecircuitslab.com/2011/06/22-watt-car-subwoofer-amplifier.html

FM Transmitter

Posted by merzaha gulhku Thursday, January 9, 2014 0 comments

                                    Image of FM Transmitter

                                    Circuit Diagram of FM Transmitter
The circuit uses only single Transistor but good voice quality. This Circuit is very simple and uses few components. Main part of the circuit is RC ( Resistance Capacitor )circuit to produce RF at required Frequency band.
Part List
Capacitor :
10 Mfd, .01 Mfd, .001Mfd, 2.2pf, 4pf, 5pf, 27pf, 68pf
Resistance :
3.3K, 2.7K, 3.9K, 220 Ohms
Transistor=494B
Mic = Condenser Mic
3V battery with Container, Switch