741 Stereo PreAmplifier Circuit Diagram

This preamp circuit provides better than 20dB gain in each channel.

A better op-amp type will give a better noise figure and bandpass.

In this circuit the roll-off is acute at 20000 Hertz.

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TDA2004 Car Battery 12W Stereo Amplifier Circuit

Its main features are :
Low distortion.
Low noise.
High reliability of the chip and of the package with additional safety during operation thanks to protections against :

• OUTPUT AC SHORT CIRCUIT TO GROUND
• VERY INDUCTIVE LOADS
• OVERRATING CHIP TEMPERATURE
• LOAD DUMP VOLTAGE SURGE
• FORTUITOUS OPEN GROUND

Space and cost saving : very low number of external components,very simple mounting system with no electrical isolation between the package and the heatsink.

The TDA2004A is a class B dual audio power amplifier in MULTIWATT package specifically designed for car radio applications.

With the component values shown and with a supply voltage of 14.4V (a fully charged car battery), the stereo amplifier is capable of delivering a power output of at least 6W, typically 6.5W with a load impedance of 4Ω. It can also handle a load impedance of 2Ω, in which case the output power is a minimum of 9W, but typically 10W. Power outputs of this order are subject to about 10% distortion, however, if lower power outputs are acceptable, 4W with a load impedance 4Ω or 6W with a load impedance of 2Ω, distortion is only in the order of 0.3%.

The voltage gain of the left-hand channel is determined by the ratio of R3 to R5, and that of the right-hand channel by the ratio of R4 to R6. With the values given, this will be 50dB. Therefore, a signal of 50mV is required at the input to give the maximum output. If this input sensitivity is too great, a 50kΩ stereo potentiometer can be included at the input. The impedance of non-inverting amplifier input is minimally 100kΩ.

The network consisting of resistor R1 and capacitor C5 (and R2, C6) is included to prevent the amplifier oscillating at high input frequencies. The bandwidth of the circuit is more than adequate for use as a car radio amplifier. The frequency response of amplifier is 40Hz to 16kHz (3dB points).

The IC must be kept sufficiently cool. The thermal resistance of the heatsink should be at least 4°C/W.

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First Response Monitor, Input Selector, Game Circuit

You can find first response using this circuit, because it helps many response monitor, games and input selectors.

Three interlocked flip-flops enable the detection of the first input.

4011 Quad 2-Input NAND gate IC

PB1, PB2 and PB3 are inputs. You can reset using PB4.

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LM3914 12V Battery Monitor Circuit

This bar graph LED battery level indicator circuit is based on LM3914 monolithic IC from National Semiconductor that senses the voltage levels of the battery and drives the 10 light emitting diodes based on the voltage level that is detected.

To calibrate the circuit it must be connected to an adjustable regulated power supply.
Connect an input voltage of 15 volt between the positive and negative poles and adjust the 10K preset until Led 10 lights up. Lower the voltage and in sequence all other Led’s will light up. Check that Led 1 lights up at approximately 10 volts.

This circuit to your own needs by making small modifications. The circuits above is set for ‘DOT’ mode, meaning only one Led at a time will be lit. If you wish to use the ‘BAR’ mode, then connect pin 9 to the positive supply rail, but obviously with increased current consumption.

The LED brightness can be adjusted up- or down by choosing a different value for the 3K9 resistor connected at pin 6 and 7.

You can also change the to monitoring voltage level.

For example, let’s say you wanted to change to 12 – 15 volt,
Remove the R2 resistor and connect 15volt to the input (+ and -) and adjust the 10K potentiometer until Led 10 lights up. Connect  200 Kilo-ohm potentiometer at pin 4 and -. Reconnect a voltage from 12 Volt to the input. Now adjust the 200K potentiometer until Led 1 lights up. When you are satisfied with the adjustment, feel free to exchange the 200K potentiometer with resistors again.(after measuring the resistance from the pot, obviously).

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WinPic PIC Programmer Software Download

This is a simple program for Win95/98/XP to program the PIC firmware from a HEX-file (the type generated by Microchip’s MPLAB^TM) into a PIC microcontroller. Most modern PICs (like the PIC16F84, 16F628, 12F675, dsPIC30Fxxxx) can be reprogrammed many times, because the program can be erased electrically (the code is stored in a FLASH, not a simple ROM). Some of the “very simple” programmer interfaces can be used, a few of them are described in the manual.

Features

• serial interface: compatible to the “COM84″, “JDM”, and user-defined
  Most interfaces for the COM-port should work without a special port-access driver, and may even work with USB<->RS-232 adapters now !
• parallel interface: compatible with SM6LKM’s “PIP84″-interface
• many other interfaces can be driven with a simple interface definition file (see manual)
• exotic interfaces can be supported through a specialized hardware-interface DLL (plugin)
• possibility to verify the PIC at different voltages (almost “production grade”)
• requires a PC with WIN95, Win98, Win XP (Win NT 4.0 and Win2000 not tested)
• Code memory size now up to 8192 words, data EEPROM memory up to 256 byte.
• Code and data memory may be programmed separately
• Bulk erase (“erase all”) or individual programming of all bytes present in from HEX-file
• Built-in “hex editor” for quick patches in code or data EEPROM memory
• Invocation with command line arguments is possible, so you can run WinPic from a shell
• Extra window with “Reload & program” function (always in front of others)
• WinPic now also supports JDM PIC-programmer 2, Velleman K8048, the Hoodmicro, the Willem interface, El Cheapo, and many others. The only(?) interfaces which WinPic doesn’t support are Microchip’s “PicStart plus” (far too expensive) and “PicKit2″ .
• Thanks to various collaborators, a French,  Greek, Portugese, Spanish, and Turkish translation of WinPic’s user interface is available. All languages are now contained in the installer (no need to download anything separately)
• Besides SMPORT, the PortTalk driver can be used. It proved to be faster under WinXP, especially when programming larger PICs (dsPIC and PIC18F).

Supported PIC microcontrollers

• dsPIC30F2010 (theoretically ALL dsPIC30F devices supported, a few tested)
• PIC16C61, PIC16C71
• PIC16C84, PIC16F84
• PIC16C710, PIC16C711, PIC16C715
• PIC10F200, PIC10F202, PIC10F204, PIC10F206
• PIC12F629, PIC12F635, PIC12F675, PIC12F683
• PIC12F609, PIC16F610, PIC12F615, PIC16F616 (new since 2007-06)
• PIC16F627, PIC16F627A, PIC16F628, PIC16F628A
• PIC16F630, PIC16F636, PIC16F648A
• PIC16F676, PIC16F684, PIC16F688
• PIC16F73, PIC16F737, PIC16F74, PIC16F76, PIC16F77
• PIC16F818, PIC16F819
• PIC16F87, PIC16F88
• PIC16F873A…PIC16F877A
• PIC16F88
• PIC18F242, PIC18F248, PIC18F252, PIC18F258
• PIC18F442, PIC18F448, PIC18F452, PIC18F458
• PIC18F2XX0/2XX5/4XX0/4XX5 (tested: PIC18F2550)
• and other “quite compatible” devices, if you have the datasheet and a text editor !

Help file including with this software.

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12V Battery Charge Nominal Discharge (Low) Indicator Circuit

This circuit monitors car battery voltage. It provides an indication of nominal supply voltage as well as low or high voltage.

741 PIN CONFIGURATION

VR1 and VR2 adjust the point at which the red, yellow and yellow, green LEDs are on or off. For example the red LED comes on at 11V, and the green LED at 12V. The yellow LED is on between these values.

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Power Supply Failure Indicator Circuit

Many circuits, especially digital systems such as random access memories and digital clocks, must have a continuous power supply to ensure correct operation. If the supply to a RAM is interrupted then the stored information is lost, as is the time in the case of a digital clock.

The supply failure indicator described here will sense the interruption of the power supply and will light a LED when the supply is restored, thus informing the microprocessor user that the information stored in RAM is garbage and must be re-entered, and telling the digital clock owner that  his clock must be reset to the correct time.

When the supply is initially switched on the inverting input of IC1 is held at 0.6V below positive supply by D2. Pressing the reset button takes the non-inverting input of IC1 to positive supply potential, so the output of IC1 swings high, holding the non-inverting input high even when the reset button is released. LED D1 is therefore not lit.

When the supply is interrupted all voltages, of course, fall to zero. Upon restoration of the supply the inverting input of IC1 is immediately pulled up to its previous potential via D2. However C1 is uncharged and holds the non-inverting input low, so the output of IC1 remains low and D1 lights.

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Resistor Color Code and Surface Mount Device (SMD) Calculator Software

Resistor Color Coder is a free desktop application that has been downloaded by hundreds of thousands of electronics enthusiasts.

4 or 5 band Leaded-Type Resistor Color Coder

This calculator quickly determines 4 or 5 band resistor values and tolerances. It can be used to encode resistance values into color codes, or to decode resistor color codes into resistance values.

Surface Mount Device (SMD) Markings Decoder

This SMD Markings Evaluator will decode 3 marking types:

• Standard 3 or 4 digit markings that can include “R” to indicate a decimal point.
  Examples: 330 3R3 4703
• EIA-96 1% markings with a number in the range 01 to 96, followed by a letter
  Examples: 22A 68C 02F
• 2, 5, and 10% markings with a letter, followed by a numbers in the range 01 to 60
  Examples: A22 C58 F59

E-Series Standard Resistance Values

Standard resistor values are listed for E-12, E-24,
E-48, E-96 and E-192 Series.

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555 Low power Consumption Timer Circuit

Normally 555 timer circuit even though the start push-button PB1 is not pressed, the timer keeps consuming power From the battery due to a potential divider formed by three 5kΩ  resistors within the IC. this power consumption known as the idling power consumption of the timer is about 3mA. This, if left connected to a battery for a long time can drain off the battery and may give unreliable operation.

To deviate this short coming, you may use the circuit given in the below. Which enables power to be drained from the battery only when timing action is ON. For the idling period, the power consumption is zero.

The circuit uses a double pole relay. One pole is used to energize the  load, the other pole is used to cut off the supply line when the timing action is over.

A push on the ‘Start’ switch energizes the relay RL1. A pair of contacts of the relay provides the supply voltage to the timer which get triggered. Oscillations start and when the output at pin 3 becomes HIGH, the diode D1 permits current to flow through the relay, thus “latching” it up. The frequency of the oscillations depends on the time constant given by T=1.1×C1×(R1+R3). After this time is over, the output at pin 3 goes LOW; the relay is released, and the load is de-energized.

Thus, so long as the start switch is not pressed, no supply voltage is provided to the IC and so, its “idling” power consumption is zero.

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PIC16F84 12 or 24 Hour Digital Clock Circuit Diagram And Programming

This PIC digital clock is based on a 16F84 microcontroller. it uses four 7-segment displays.The software in the microcontroller allows for very accurate timekeeping.

PB1 for set minutes.

PB2 for set hours.

PB3 for Reset.

D1 LED indicate seconds.

Notes:

• Design this circuit diagram on veroboard or pcb using 18 pin IC base.
• Program your PIC (pic16f84 or pic16f84a) using PIC Programmer with ic-prog programmer software and this .HEX file. You can follow these instructions.
• Install PIC on IC base.
• Supply power to your circuit and set time using PB1 and PB2.

Thats all.

PIC16F84 Pin Configuration

Also provided asm files, so you can develop or modify this clock circuit.

Download digital clock asm and hex files.

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