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Signal Tracer

The main part of this circuit is the LM386 amplifier chip. It also uses a transistor input to buffer the input signal and provide extra gain for the LM386. The little unit has helped me out on numerous occasions when trouble shooting any amplifier circuit like a stereo receiver, tv / vcr audio section, radios, cd players and car stereos.

Circuit Diagram

Signal Tracer circuit diagram

1999 Chevrolet Chevy Tahoe Wiring Diagram

1999 Chevrolet Chevy Tahoe Wiring Diagram


The Part of 1999 Chevrolet Chevy Tahoe Wiring Diagram: power distribution cell, gauges, link
connector, diesel, fuse block,  steering ctrl, vehicle, engine ctrl, powertrain ctrl module, steering wheel position signal, case ctrl, passlock sensor, scurity lamp, instrument cluster, passlock module, black wire, cylinder, hall effect, magnet

Four Stage FM Transmitter

This FM transmitter circuit uses four radio frequency stages: a VHF oscillator built around transistor BF494 (T1), a preamplifier built round transistor BF200 (T2), a driver constructed round transistor 2N2219 (T3) and a power amplifier built around transistor 2N3866 (T4). A condenser microphone is connected at the enter of the oscillator.
Circuits diagram :
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Four-Stage FM Transmitter Circuits Diagram

Working of the circuit is inconspicuous. When you discuss close to the microphone, frequency-modulated alerts are bought at the collector of oscillator transistor T1. The FM alerts are amplified via the VHF preamplifier and the pre-driver stage. You may additionally use transistor 2N5109 rather than 2N2219. The preamplifier is a tuned class-A RF amplifier and the using force is a class-C amplifier. Signals are ultimately fed to the class-C RF energy amplifier, which delivers RF power to a 50-ohm horizontal dipole or ground airplane antenna. Use a heat-sink with transistor 2N3866 for heat dissipation. Carefully adjust trimmer VC1 connected across L1 to generate frequency within 88-108 MHz. Also modify trimmers VC2 thru VC7 to get maximum output at most vary. 

Regulator IC 78C09 offers stable 9V provide to the oscillator, so edition in the provide voltage won't have an impact on the frequency generated. You can also use a 12V battery to energy the circuit.

Assemble the circuit on a general-purpose PCB. Install the antenna properly for maximum vary. Coils L1 via L5 are made with 20 SWG copper-enamelled wire wound over air-cores having 8mm diameter. They have 4, 6, 6, 5 and seven turns of wire, respectively.  

EFY note. This transmitter is meant handiest for educational functions. use of this transmitter with outdoor antenna is against the law in most sections of the arena. The author and EFY might no longer be chargeable for any misuse of this transmitter.


Author : Pradee G.  - Copyright : EFY

0 30 Volt Power Supply

linear power supply, shown in the schematic, provides 0-30 volts, at one amp, maximum, using a discrete transistor regulator with op amp feedback to control the output voltage. The supply was constructed in 1975-6 & has a constant current mode that is used to recharge batteries.




With reference to the schematic, lamp, LP2, is a power on indicator. The other lamp (lower) lights when the unit reaches its preset current limit. R5, C2, & Q10 (TO-3 case) operate as a capacitor multiplier. The 36 volt zen-er across C2 limits the maximum supply voltage to the op amps supply pins. D5, C4, C5, R15, & R16 provide a tiny amount of negative supply for the op amps so that the op amps can operate down to zero volts at the output pins (pins 6). A more modern design might eliminate these four parts & use a CMOS rail-to-rail op-amp. Current limit is set by R3, D1, R4, R6, Q12, R10, & R13 providing a bias to U2 that partially turns off transistors Q9 & Q11 when the current limit is reached. R4 is a front panel potentiometer that sets the current limit, R22 is a front panel potentiometer that sets the output voltage (0-30 volts), & R11 is an internal trim-pot for calibration. The meter is a one milliamp meter with an internal resistance of 40 ohms. Switch S1 determines whether the meter reads 0-30 volts, or 0-1 amp.




A more new circuit might use a single IC regulator, such as the MC78XX, or MC79XX series, immediately after the half wave rectifier, to replace about 30 parts, or at least a high precision zen-er diode to replace D10 as the voltage reference. The LM4040 is such voltage reference & has excellent stability over temperature. IC regulators such as the MC78XX series may finally become obsolete as newer IC regulators are designed, however, discrete transistors, op-amps, & zeners are more generic, have an extended production lifespan, & permit the designer to demonstrate that they understands the principles of linear regulated power supply operation.

Light Switch Wiring

Light Switch Wiring Diagram on Light And Outlet 2 Way Switch Wiring Diagram
Light And Outlet 2 Way Switch Wiring Diagram.


Light Switch Wiring Diagram on Wire How To Wiring Diagram  Single Switch And Light  Alternate
Wire How To Wiring Diagram Single Switch And Light Alternate.


Light Switch Wiring Diagram on How To Wire A Switch   Switch And Light At End Of Circuit
How To Wire A Switch Switch And Light At End Of Circuit.


Light Switch Wiring Diagram on Two Way Light Switch Wiring
Two Way Light Switch Wiring.


Light Switch Wiring Diagram on Wiring A Light Switch For A Ceiling Light Diy Project
Wiring A Light Switch For A Ceiling Light Diy Project.


Light Switch Wiring Diagram on Honda Civic Hybrid Fog Light Wiring Circuit Schematic Diagram   Arya
Honda Civic Hybrid Fog Light Wiring Circuit Schematic Diagram Arya.


Light Switch Wiring Diagram on Light Switch Diagram  Power Into Light     Pdf  44kb
Light Switch Diagram Power Into Light Pdf 44kb.


Light Switch Wiring Diagram on Vn800 Turn Signal Light Circuit   Wiring Diagram   Circuit Schematic
Vn800 Turn Signal Light Circuit Wiring Diagram Circuit Schematic.


Light Switch Wiring Diagram on Home Outdoor Lighting Wiring Diagram
Home Outdoor Lighting Wiring Diagram.


Light Switch Wiring Diagram on Wiring Diagram Light Switch Wiring Diagram Light Switch 64038
Wiring Diagram Light Switch Wiring Diagram Light Switch 64038.


Alternator Bracket Mounting Line Wiring

Alternator Wiring on Do This An Nothing Else
Do This An Nothing Else.


Alternator Wiring on Alternator Regulator Troubleshooting
Alternator Regulator Troubleshooting.


Alternator Wiring on Alternator Bracket For The Top Mounting About   15 On Line The Wiring
Alternator Bracket For The Top Mounting About 15 On Line The Wiring.


Alternator Wiring on 1994 Saturn Sl2 Problem New Alternator Bad Electrical 4 Cyl Front
1994 Saturn Sl2 Problem New Alternator Bad Electrical 4 Cyl Front.


Alternator Wiring on 6610s Alternator Wiring   Yesterday S Tractor Co
6610s Alternator Wiring Yesterday S Tractor Co.


Alternator Wiring on Thread  Toyota Alternator Install
Thread Toyota Alternator Install.


Alternator Wiring on Image Hosting  Free Photo Sharing   Video Sharing At Photobucket
Image Hosting Free Photo Sharing Video Sharing At Photobucket.


Alternator Wiring on 12v Marine Tachometer Diesel Alternator Wiring Instruction
12v Marine Tachometer Diesel Alternator Wiring Instruction.


Alternator Wiring on 1972 Ford F100 Alternator Voltage Regulator Wiring   Fixya
1972 Ford F100 Alternator Voltage Regulator Wiring Fixya.


Alternator Wiring on Delco One Wire Alternator Installation On 5000 Ford Mf135 Wiring Rjs
Delco One Wire Alternator Installation On 5000 Ford Mf135 Wiring Rjs.


Battery Charger with Temeperature Sensor

Battery Charger with Temeperature Sensor


Battery with a LM35 temperature sensor on the charger used to monitor the battery temperature is in charge. Battery temperature sensor is needed because the battery temperature will rise at the time in charge. Battery temperature sensor LM35 temperature sensor has high accuracy in monitoring the battery temperature, it is because the temperature sensor LM35 is a temperature sensor that can convert temperature changes into voltage changes linearly.


At the time of the charge a battery will experience changes in temperature, where the battery temperature will begin to rise when the battery began to fill. To avoid over heat the battery, the battery temperature sensor LM35 temperature sensor is required to terminate the battery charging current to avoid overheating.

battery charger schematic with LM35
Battery charger with temperature sensor schematic

On the battery charger circuit temperature sensor with temperature sensor 35 lm above the R1 is used for setting the maximum value of the desired temperature. Therefore, when the temperature was in-charge the battery begins to rise and reach temperatures setup then this series will break the current battery charge.

Light Dependent Resistors

LDRs or lightweight Dependent Resistors are terribly helpful particularly in light/dark sensor circuits. Normally the resistance of an LDR is incredibly high, typically as high as a thousand 000 ohms, however once they are illuminated with lightweight resistance drops dramatically.


 The animation opposite shows that when the torch is turned on, the resistance of the LDR falls, permitting current to have it.Circuit Wizard software has been used to show, the vary of values of a ORP12, LDR .
When a light-weight level of a thousand lux (bright light) is directed towards it, the resistance is 400R (ohms).


When a light-weight level of ten lux (very low light level) is directed towards it, the resistance has risen dramatically to ten.43M (10430000 ohms).

This is an example of a light-weight sensor circuit :

When the sunshine level is low the resistance of the LDR is high. This prevents current from flowing to the bottom of the transistors. Consequently the LED doesnt lightweight. However, when lightweight shines onto the LDR its resistance falls and current flows into the bottom of the primary transistor and then the second transistor. The LED lights.

The preset resistor will be turned up or right down to increase or decrease resistance, during this means it will build the circuit additional or less sensitive.






Source by : Streampowers

Solar Powered SLA Battery Maintenance

This circuit was designed to ‘baby-sit’ SLA (sealed lead-acid or ‘gel’) batteries using freely available solar power. SLA batteries suffer from relatively high internal energy loss which is not normally a problem until you go on holidays and disconnect them from their trickle current charger. In some cases, the absence of trickle charging current may cause SLA batteries to go completely flat within a few weeks. The circuit shown here is intended to prevent this from happening. Two 3-volt solar panels, each shunted by a diode to bypass them when no electricity is generated, power a MAX762 step-up voltage converter IC. 

Circuit diagram:
Solar Powered SLA Battery-Maintenance-Circuit-Diagram
Solar Powered SLA Battery Maintenance Circuit Diagram

The ‘762 is the 15-volt-out version of the perhaps more familiar MAX761 (12 V out) and is used here to boost 6 V to 15 V.C1 and C2 are decoupling capacitors that suppress high and low frequency spurious components produced by the switch-mode regulator IC. Using Schottky diode D3, energy is stored in inductor L1 in the form of a magnetic field. When pin 7 of IC1 is open-circuited by the internal switching signal, the stored energy is diverted to the 15-volt output of the circuit. The V+ (sense) input of the MAX762, pin 8, is used to maintain the output voltage at 15 V. C4 and C5 serve to keep the ripple on the output voltage as small as possible. R1, LED D4 and pushbutton S1 allow you to check the presence of the 15-V output voltage.

D5 and D6 reduce the 15-volts to about 13.6 V which is a frequently quoted nominal standby trickle charging voltage for SLA batteries. This corresponds well with the IC’s maximum, internally limited, output current of about 120 mA. The value of inductor L1 is not critical — 22 µH or 47 µH will also work fine. The coil has to be rated at 1 A though in view of the peak current through it. The switching frequency is about 300 kHz. A suggestion for a practical coil is type M from the WEPD series supplied by Würth (www.we-online.com). Remarkably, Würth supply one-off inductors to individual customers. At the time of writing, it was possible, under certain conditions, to obtain samples, or order small quantities, of the MAX762 IC through the Maxim website at www.maxim-ic.com.
 
 
Streampowers

Honda XL100 Electrical Wiring Diagram

Honda XL100 Electrical Wiring Diagram
The Part of Honda XL100 Electrical Wiring Diagram: high beam indicator, meter light, speedometer,
tachometer, fuse, headlight control switch,silicon rectifier, wire harness, tail light, sub cord, tail/stop light, condenser, contact breaker, spark plug, horn, turn signal, headlight, emergency kill switch, main switch, stop switch, battery, neutral switch.

Digital Object Counter using LDR and digital IC 7490

This is the simple circuit on Hobby Electronics. In this circuit three modules are used in object counter. 555 timer are used as a monostable mode and astable mode. The other is counter module.

In this circuit 555 timer
configured as a monostable mode, is a simple automatic dark sensor
circuit that gives output when light falling is blocked on LDR. Pin 3 of
monostable circuit has been connected to pin 4 of astable timer. When
monostable circuit generates output, astable mode timer starts giving pulses to the counter module. Frequency for counter module is set up using R4, R3 and C2.

7490acts as a decade counter and 7447 uses the output of 7490
to display numbers on seven segment display. This circuit counts from 0
to 9. You can count 0 to 100 modifying counter module circuit. Just
adding few components as well as two counter ic, two display driver and two display. For count 0 to 100, comments on the comments box. You will get complete circuit.
The output will be: If you block light falling on LDR, the number on seven segment display will increase.

10 000x With One Transistor

For a collector follower with emitter resistor, you’ll often find that the gain per stage is no more than 10 to 50 times. The gain increases when the emitter resistor is omitted. Unfortunately, the distortion also increases. With a ubiquitous transistor such as the BC547B, the gain of the transistor is roughly equal to 40 times the collector current (Ic), provided the collector current is less than a few milliamps. This value is in theory equal to the expression q/KT, where q is the charge of the electron, K is Boltzmann’s constant and T is the temperature in Kelvin.

For simplicity, and assuming room temperature, we round this value to 40. For a single stage amplifier circuit with grounded emitter it holds that the gain Uout /Uin (for AC voltage) is in theory equal to SRc. As we observed before, the slope S is about 40Ic. From this follows that the gain is approximately equal to 40I cRc. What does this mean? In the first instance this leads to a very practical rule of thumb: that gain of a grounded emitter circuit amounts to 40·I c·Rc, which is equal to 40 times the voltage across the collector resistor.

If Ub is, for example, equal to 12 V and the collector is set to 5V, then we know, irrespective of the values of the resistors that the gain will be about 40R(12–5) = 280. Notable is the fact that in this way the gain can be very high in theory, by selecting a high power supply voltage. Such a voltage could be obtained from an isolating transformer from the mains. An isolating transformer can be made by connecting the secondaries of two transformers together, which results in a galvanically isolated mains voltage.

Circuit diagram:

That means, that with a mains voltage of 240 Veff there will be about 340 V DC after rectification and filtering. If in the amplifier circuit the power supply voltage is now 340 V and the collector voltage is 2 V, then the gain is in theory equal to 40 x (340–2). This is more than 13,500 times! However, there are a few drawbacks in practice. This is related to the output characteristic of the transistor. In practice, it turns out that the transistor does actually have an output resistor between collector and emitter.

This output resistance exists as a transistor parameter and is called ‘hoe’. In normal designs this parameter is of no consequence because it has no noticeable effect if the collector resistor is not large. When powering the amplifier from 340 V and setting the collector current to 1 mA, the collector resistor will have a value of 338 k. Whether the ‘hoe’-parameter has any influence depends in the type of transistor. We also note that with such high gains, the base-collector capacitance in particular will start to play a role.

As a consequence the input frequency may not be too high. For a higher bandwidth we will have to use a transistor with small Cbc, such as a BF494 or perhaps even an SHF transistor such as a BFR91A. We will have to adjust the value of the base resistor to the new hfe. The author has carried out measurements with a BC547B at a power supply voltage of 30 V. A value of 2 V was chosen for the collector voltage. Measurements confirm the rule of thumb. The gain was more than 1,000 times and the effects of ‘hoe’ and the base-collector capacitance were not noticeable because of the now much smaller collector resistor.
Author: Gert Baars
Copyright: Elektor Electronics

1994 Lumina APV Van Wiring Diagram

1994 Lumina APV Van Wiring Diagram


The Part of 1994 Lumina APV Van Wiring Diagram: camshaft position sensor, hall effect, sensor ground,
amplifier, instrument cluster, red wire, bypass switch, control reference, ignition module control, electronic ignition module, powertrain control module, spark reference input

RGB Solar Lamp

This deluxe solar-powered light  uses a battery and solar cells salvaged from a solar lamp with a four-cell battery (4.8 V nominal terminal  voltage).
Circuit diagram :
RGB Solar Lamp-Circuit Diagram
RGB Solar Lamp Circuit Diagram

The circuit can operate from any  DC voltage around this value and  its current consumption, at 20 mA,  is low. This means that the battery  can give up to five days of operation. The circuit consists of an Atmel  ATtiny microcontroller which drives  a red, a green and a blue LED directly  from three port pins. Series resistors are of course included to limit  the LED current. The microcontroller  drives the LEDs in sequence to produce an  RGB running light effect. The microcontroller  is also responsible for ensuring that the light automatically switches on when it gets dark  and off when it is light. The light sensor is  made from one of the solar cells from a bro-ken solar lamp (it is more common  for the battery to fail rather than  the solar cells). 

The power output of this cell is not  important, as the microcontroller  only measures its output voltage  using its internal A/D converter  connected to pin PB4. The project is  ideal for beginners, as a ready-programmed microcontroller is avail-able from the Elektor Shop (order  code 100581-41). 



Source by : Streampowers

Simple Remote Control Tester

Nearly always when a remote control doesn’t work, the underlying problem is elementary: the unit does not emit light. The cause may be dry solder joints, defective LEDs etc., but also a flat battery (perhaps due to stuck key). The human eye is unable to perceive infra-red light. By contrast, an ordinary photo transistor like the BP103 has no problems working in the infrared spectrum, so in the circuit here it simply biases the BC558 which, in turn, makes LED D1 flash in sympathy with the telegram from the remote control. The preset in the circuit determines the sensitivity.

Simple Remote Control Tester circuit diagram

1983 Ford Thunderbird Wiring Diagram

1983 Ford Thunderbird Wiring Diagram



 (click for full size image)
The Part of 1983 Ford Thunderbird Wiring Diagram :windshield, wiper, motor, windshield washer pump, fuse block, stop light switch, backup light switch, neutral safety switch, blower motor, oil press switch, condenser, breaker, temp.gauge(eng.unit), distributor, cyl, breaker, condenser, distributor, cyl, coil, starter, alternator, yellow, brown, starter relay, black-yellow, alternator regulator, horn, parking light, direction signal, high beam, battery, low beam, low beam, high beam, direction signal, parking light.

Wireless FM Transmitter

The wireless fm transmitter circuit described here has an extra RF power amplifier stage, after the oscillator stage, to raise the power output to 200-250 milliwatts. With a good matching 50-ohm ground plane antenna or multi-element Yagi antenna, this wireless fm transmitter can provide reasonably good signal strength up to a distance of about 2 kilometers.
The wireless transmitter circuit built around transistor T1 (BF494) is a basic low-power variable-frequency VHF oscillator. A varicose diode circuit is included to change the frequency of the fm transmitter and to provide frequency modulation by audio signals. The output of the oscillator is about 50 milliwatts. Transistor T2 (2N3866) forms a VHF-class A power amplifier. It boosts the oscillator signals’ power four to five times. Thus, 200-250 milliwatts of power is generated at the collector of transistor T2.
FM wireless transmitter circuit diagramfm transmitter circuit diagram For better results, assemble the circuit on a good-quality glass epoxy board and house the transmitter inside an aluminium case. Shield the oscillator stage using an aluminium sheet.
Coil winding details are given below:

L1 – 4 turns of 20 SWG wire close wound over 8mm diameter plastic former.
L2 – 2 turns of 24 SWG wire near top end of L1.
(Note: No core (i.e. air core) is used for the above coils)
L3 – 7 turns of 24 SWG wire close wound with 4mm diameter air core.
L4 – 7 turns of 24 SWG wire-wound on a ferrite bead (as choke)

Potentiometer VR1 is used to vary the fundamental frequency whereas potentiometer VR2 is used as power control. For hum-free operation, operate the wireless fm transmitter on a 12V rechargeable battery pack of 10 x 1.2-volt Ni-Cd cells. Transistor T2 must be mounted on a heat sink. Do not switch on the transmitter without a matching antenna. Adjust both trimmers (VC1 and VC2) for maximum transmission power. Adjust potentiometer VR1 to set the fundamental frequency near 100 MHz.
This fm wireless transmitter should only be used for educational purposes. Regular transmission using such a transmitter without a licence is illegal in most countries.

6V Ultra Bright LED Chaser

This is a spectacular but completely useless project. It lights Ultra-Bright LEDs in a sequence and each LED flashes brightly very briefly. The LEDs light-up going around and around since they are mounted in a circle (on a CD), then they pause before chasing again. The very brief flash of each LED (15ms) and the pauses (1 second) reduce the average current so the battery should last a long time.
 
For user convenience, this project has a stepper speed control and a brightness control. At slower speeds and/or reduced brightness, the battery’s life is extended considerably.

At full brightness, the LEDs flash extremely brightly. More than one of this project grouped together occasionally synchronize, lighting the whole room for a moment.

Operation
At maximum speed, the LEDs don’t appear to flash, instead they appear to move from one lighted one to the next, around and around. They rotate completely for 4 rotations in two seconds, and then turn off for a one second pause then repeat the sequence. At a lower speed, the number of rotations before the pause is less. It will do three rotations, two or even only one rotation at its slowest speed. A sequence of rotations starts with LED #2 and end with LED #9. 


Specifications

Battery: Four AA alkaline cells.
Battery life:

                        Minimum speed and brightness              2.3 years
                        Medium speed and brightness                 1 year
                        Minimum speed, maximum brightness   4.1 months
                        Maximum speed and brightness              3.8 weeks

Brightness: controlled with Pulse width Modulation, from off to extremely bright (4000mcd).
Stepper speed: 2 LEDs/sec to 2 revolutions/sec.

Pulse Width Modulation frequency: 3.9KHz.
LED current: 24mA pulses.
LED voltage drop: 3.2V at 24mA. Blue, green and white Ultra-Bright LEDs are suitable.
Minimum battery voltage:
                         <3V, oscillators do not run.
                         3V, LEDs are very dim.
                         4V, LEDs reach almost full brightness.

Radio interference: none.
 
Circuit Description
  • The CD74HC4017N high-speed Cmos IC is rated for a maximum supply voltage of 7V. It is rated for a maximum continuous output current of 25mA. In this project, the maximum supply voltage is 6.4V with brand new battery cells and the 24mA output current is so brief that the IC runs cool.
  • The MC14584BCP* IC (Motorola) is an ordinary “4XXX series” 3V to 18V Cmos IC, with a very low operating current and low output current. Its extremely high input resistance allows this project to use high value resistors for its timers and oscillators, for low supply current. Its 6 inverters are Schmitt triggers for simple oscillators and very quick switching.
  • IC2 is a 10 stage Johnson counter/decoder. On the rising edge of each clock pulse its outputs step one-at-a-time in sequence. It drives the anode of each conducting LED toward the positive supply.
  • IC1 pins 1 and 2 is a Schmitt trigger oscillator with C3 and C4 paralleled for a very low frequency. R1 and R2 control its frequency and the diodes with R3 combine with the capacitors to produce the 15mS on time for the LEDs.
  • IC1 pins 5 and 6 is the brightness Pulse Width Modulation oscillator. The pot R7 with the associated diodes and resistors allow it to change the duty-cycle of its output for PWM brightness control. It drives the transistor.
  • IC1 pins 3 and 4 is an inverter. It takes the low time (LEDs off) from the clock oscillator, inverts it to a high and shuts-off the brightness oscillator through diode D6.
  • IC1 pins 11 and 10 is a sample-and-hold stage. It takes a sample of the pulse driving LED #9 though D3 and R4 and charges C5 in steps. At maximum speed it takes 4 steps for C5 to charge to the Schmitt switching threshold voltage. R5 and D5 slowly discharge C5 for the pause time.
  • IC1 pins 13 and 12 is an inverter that resets the counter/decoder and shuts-off the clock oscillator through D4, during the pause time.
  • IC1 pins 9 and 8 is not used and is shut-off by grounding its input.
  • T1 is the PWM switching transistor. R9 limits the maximum LED current to 24mA.

Construction
The 10 LEDs mount on a Compact-Disc which is glued to a plastic box with contact cement. The box houses the Veroboard circuit in its lower main part with the battery holders on its lid. Multiconductor ribbon cable joins the LEDs to the circuit. The pots mount on the sides of the box.
If you turn it down each night, its current is so low an on-off switch isn’t needed.


Parts List

1 IC1 MC14584BCP (Motorola) * Ordinary Cmos hex Schmitt trigger inverters
1 IC2 CD74HC4017N High-speed Cmos decade counter/decoder
1 T1 2N3904 or 2N4401 NPN transistor
8 D1 to D8 1N4148 or 1N914 Diodes
10 LEDs Blue, green or white Ultra-Bright LEDs with Vf = 3.2V or less at 20mA
1 R1 100K 1/4W resistor
1 R2 1M Linear-taper potentiometer
1 R3 33K 1/4W resistor
1 R4 2.2M 1/4W resistor
1 R5 22M 1/4W resistor
1 R6 47K 1/4W resistor
1 R7 1M Audio-taper (logarithmic) potentiometer
1 R8 1.8K 1/4W resistor
1 R9 68 ohms 1/4W resistor

1 C1 100uF/16V Electrolytic capacitor

1 C2 0.1uF/50V Ceramic capacitor
2 C4 and C4 1uF/63V Metalized poly capacitor
1 C5 470nF Metalized poly capacitor
2 C6 and C7 1nF Metalized poly capacitor
 
* A CD74C14 can also be used for IC1 but R4 = 1M, R5 = 10M, C3 and C5 = 330nF, C4 = 470nF.

A 3V LED Chaser project also works well with these changed parts but using a CD74HC14N for IC1.
In addition to these changes, R8 = 680 ohms and R9 = 22 ohms. I built one using low-voltage (1.8V at 20mA) orange Ultra-Bright LEDs. The orange one looks good beside the green one.

Attachments: 6V LED Ultra-Bright Chaser schematic, Veroboard layout and 3 pictures.

I wish I knew how to take a slow picture with my son’s digital camera, so all the LEDs would be lighted, and if I moved it would make nice lighted smears in the picture.
 

Photos

Crowbar Speaker Protection

Crowbar circuits are so-called because their operation is the equivalent of dropping a crowbar (large steel digging implement) across the terminals. It is only ever used as a last resort, and can only be used where the attached circuit is properly fused or incorporates other protective measures.

A crowbar circuit is potentially destructive - if the circuitry only has a minor fault, it will be a major fault by the time a crowbar has done its job. It is not uncommon for the crowbar circuit to be destroyed as well - the purpose is to protect the device(s) attached to the circuit - in this case, a loudspeaker.

Description 
 
Theres really nothing to it. A resistor / capacitor circuit isolates the trigger circuit from normal AC signals. Should there be enough DC to activate the DIAC trigger, the cap is discharged into the gate of the TRIAC, which instantly turns on ... hard. A TRIAC has two basic states, on and off. The in-between state exists, but is so fast that it can be ignored for all intents and purposes.

Crowbar Speaker Protection Circuit diagram:

Crowbar Speaker Protection Figure 1 - Crowbar Speaker Protector

The BR100 DIAC (or the equivalent DB3 from ST Microelectronics) is rated for a breakdown voltage of between 28 and 36V - these are not precision devices. Needless to say, using the circuit with supply voltages less than around 40V is not recommended, as you will have a false sense of security. The supply voltage must be higher than the breakdown voltage of the DIAC, or it cannot conduct. Zeners cannot be used as a substitute for lower voltages - a DIAC has a negative impedance characteristic, so when it conducts, it will dump almost the full charge in C1 into the gate of the TRIAC. This is essential to make sure the TRIAC is switched into conduction.

The TRIAC is a common type, and may be substituted if you know the specifications. Its rated at 12A, but the peak current (non-repetitive) is 95A, and it only needs to sustain that until the fuse (or an output transistor) blows. A heatsink is preferred, but there is a good chance that the TRIAC will blow up if it has to protect your speakers, so it may not matter too much. The 0.47 ohm resistor is simply to ensure that the short circuit isnt absolute. This will limit the current a little, and increases the chance that the TRIAC will survive (albeit marginally). Feel free to use a BT139 if it makes you feel better - these are rated at 16A continuous, and 140A non-repetitive peak current.

The peak short circuit current will typically be about 90A for a ±60V supply, allowing ~0.2 ohms for wiring resistance and the intrinsic internal resistance of the TRIAC, plus the equivalent series resistance of the filter capacitors. Thats a seriously high current, and it will do an injury to anything thats part of the discharge path. Such high currents are not advised for filter caps either, but being non-repetitive they will almost certainly survive.

Construction & Use 
 
Apart from the obvious requirement that you dont make any mistakes, construction is not critical. Wiring needs to be of a reasonable gauge, and should be tied down with cable ties or similar. C1 must be polyester. While a non-polarised electrolytic would seem to be acceptable, the circuit will operate if the capacitor should dry out over the years. This means it will lose capacitance, and at some point, the crowbar may operate on normal programme material. This would not be good, as it will blow up your amplifier!

Make sure that all connections are secure and well soldered. Remember that this is the last chance for your speakers, so it needs to be able to remain inactive for years and years - hopefully it will never happen. The circuit doesnt have to be mounted in the amplifier chassis - it can be installed in your speaker cabinet. Nothing gets hot unless it operates, at which point no-one really cares - it just has to save the speakers from destruction once to have been worthwhile.

Remember that the crowbar circuit absolutely must never be allowed to operate with any normal signal. A perfectly good amplifier that triggers the circuit because of a high-level bass signal (for example) will very likely be seriously damaged if the crowbar activates. To verify that no signal can trigger it, you may want to (temporarily) use a small lamp in place of R2, and drive the amp to maximum power with bass-heavy material.

A speaker does not need to be connected. If the lamp flashes, your amp would have been damaged. If this occurs, you may want to increase the value of C1. Note that bipolar electrolytics should never be used for C1, because they can dry out and lose capacitance as they age. This could cause the circuit to false-trigger.

Source : http://www.ecircuitslab.com/2011/06/crowbar-speaker-protection.html

Video Out Coupling

If you want to connect a video signal to several destinations, you need a distribution amplifier to match the 75-ohm video cable. A distribution amplifier terminates the incoming cable in 75 ohms and provides several outputs, each with 75-ohm output impedance. Since this is usually achieved by putting a 75-ohm series resistor in the output lead of each video opamp (current-feedback amplifier), the opamps must be set up for a gain of 2 in order to achieve an insertion gain of 1 (0 dB). The disadvantage of this arrangement is that if the amplifier or its power supply fails, no signal is available at any of the outputs. This can be remedied by using a high input impedance amplifier, which can be tapped into a video line without having to have its own 75-ohm termination resistor.

Video-Out Couplingq 

Farmula Video-Out Couplingw

In order to eliminate hum interference and voltage differences between the cable screen and the circuit earth, the circuit exploits the common-mode rejection of the opamp. This can be optimized with resistor RG1. With the indicated LT1396 video opamp, more than 40 dB of common-mode rejection can be achieved. The signal bandwidth of the circuit can be optimized using the trimpots. It reaches to more than 10 MHz, which is quite acceptable for video signals. Thanks to the high-impedance connection to the video line, the video signal is not affected when the power for the coupled amplifier is switched off. You can learn more about the LT1396 from its data sheet at http://www.linear-tech.com.

Laptops Cord Stays off Your Lap with this Clip

Someone just got this trick works on all the uni body Mac Books and helps keep your wires and cord under control.

Hacks and Mods: Laptops Cord Stays off your Lap with this Clip

This clip is especially bendy if you are lounging on the sofa with the power-cord-side in towards the cushions. It keeps your MacBooks power cord under control with this trick and to stop it from tugging in you. Its built-in cable clip the one that keeps your cord wrapped around the power brick and clip it to the side of your laptops screen.
Hacks and Mods:   Laptops Cord Stays off your Lap with this Clip
The cable pulls it up off your lap and keeps it neat and tidy not to mention free of crazy fall across the keyboard loops.
 
 
 
Source by : Streampowers