White LED Flashlight Conversions

Many flashlights can be easily converted to use white LEDs instead of regular incandescent bulbs. The flashlight can quickly be returned to its original bulb and battery configuration later if you wish. Of course this procedure will void the warranty on your flashlight, but the only permanent modification made is increasing the size of the hole in the reflector assembly. Since I live in a remote area with no streetlights and am a volunteer firefighter, flashlights are very important and are used daily by everyone in the family. I normally use Maglite® flashlights in different sizes for reliability reasons, but have been frustrated with short battery and bulb life. I normally get only 5 hours on 2xAA batteries, and have to change bulbs every 2 sets of batteries or so. Converted white LED MiniMaglites® have become my favorite flashlights! Though the LED conversions are not as bright as normal bulbs, the batteries last over 6 times as long, and I have not replaced an LED bulb yet despite running them at over their maximum current. Otherpower.com sells super-bright white LEDs that are perfect for flashlight conversions, plus LED clusters that fit normal automotive taillight bulb sockets, available at any auto parts store. We made various attempts at figuring out how to mass-produce the spacer with resistor -- and we've decided not to offer them for sale because we can't manufacture them cheaply. Much better to make your own anyway! You can check out our line of efficient lighting products in the Renewable Energy section of our web shopping cart. MiniMaglite® LED ConversionsAlkaline batteries are often the best choice for flashlights, since they retain more power when sitting unused for long periods of time. And you can expect over 6 times longer battery life when using a white LED bulb! This is important when a flashlight must sit in your truck for weeks or months without use. In this situation, NiCad or NiMh rechargables would most likely have little power left in them after sitting for months. Alkaline N-cells are inexpensive and usually locally .

 Take off the flashlight head and remove the incandescent bulb. Save the bulb for future use if you ever decide to return your flashlight to its original condition.  Trim the tabs off of the LED leads using nippers. A flat needle file or sandpaper can help smooth the lead.  Trim the LED leads off to 1/4 inch in length.  Insert the LED into the bulb socket. If does not light up, reverse the LED and it will. If not, check your batteries, and also make sure the LED leads are not touching each other.  Remove the reflector, and using a 1/4 inch drill bit carefully widen the hole for the bulb to 1/4 inch. Our LED bulbs do not need reflectors since they emit light at a set 20° angle, but the reflector assembly is needed in a MiniMaglite® for the switch to function properly. Now try your flashlight with the original AA batteries. It should light up, but somewhat dimmly. If you run it like this, the batteries will last for weeks of continous on-time. It's not very bright, but it is enough light to find the keyhole or make your way to the bathroom. To run the LED at full brightness you'll need to use 3 N cells. Next,  Install the 3 N-cell batteries.  Install a spacer (containing an internal current-limiting resistor) You'll need to build a spacer to hold the resistor and make the whole battery pack come out to the right length. Our prototype used a 3/8 inch length of 1/2 inch diameter wooden dowel (see photos below). We drilled short holes at the ends of the dowel for battery contacts made of small machine screws. We then drilled an off-center hole all the way through the spacer for the resistor, and wrapped each resistor lead around the contacts.

Emergency Light

Emergency Light
The circuit of automatic emergency light presented here has the following features: 1. When the mains supply (230V AC) is available, it charges a 12V battery up to 13.5V and then the battery is disconnected from the charging section. 2. When the battery discharges up to 10.2V, it is disconnected from the load and the charging process is resumed. 3. If the mains voltage is available and there is darkness in the room, load (bulb or tube) is turned on by taking power from the mains; otherwise the battery is connected to the load. 4. When the battery discharges up to 10.2V and if the mains is not yet available, the battery is completely disconnected from the circuit to avoid its further discharge. The mains supply of 230V AC is stepped down to 18V AC (RMS) using a 230V AC primary to 0-18V AC, 2A secondary transformer (X1), generally used in 36cm B&W TVs. Diodes D1 through D4 form bridge rectifier and capacitor C5 filters the voltage, providing about 25V DC at the output. Charging section includes 33-ohm, 10-watt resistor R2 which limits the charging current to about 425 mA when battery voltage is about 10.2V, or to 325 mA when battery voltage is about 13.5V. When the battery charges to 13.5V (as set by VR2), zener diode D17 goes into breakdown region, thereby triggering triac TR1. Now, since DC is passing through the triac, it remains continuously ‘on’ even if the gate current is reduced to zero (by disconnecting the gate terminal). Once the battery is fully charged, charging section is cut-off from the battery due to energisation of relay RL2. This relay remains ‘on’ even if the power fails because of connection to the battery via diode D10. S4, a normally closed switch, is included to manually restart the charging process if required. Battery disconnect and charging restart section comprises an NE555 timer (IC2) wired in monostable mode. When the battery voltage is above 10.2V (as indicated by red LED D15), zener diode (D16) remains in the breakdown region, making the trigger pin 2 of IC2 high, thereby maintaining output pin 3 in low voltage state. Thus, relay RL3 is ‘on’ and relay RL4 is ‘off.’ But as soon as the battery voltage falls to about 10.2V (as set by preset VR1), zener diode D16 comes out of conduction, making pin 2 low and pin 3 high to turn ‘on’ relay RL4 and orange LED D13. This also switches off relay RL3 and LED D15. Now, if the mains is available, charging restarts due to de-energisation of relay RL2 because when relay RL4 is ‘on,’ it breaks the circuit of relay RL2 and triac TR1. But if the mains supply is not present, both relays RL3 and RL1 de-energise, disconnecting the battery from the remaining circuit. Thus when battery voltage falls to 10.2 volts, its further discharge is eliminated. But as soon as the mains supply resumes, it energises relay RL1, thereby connecting the battery again to the circuit. Light sensor section also makes use of a 555 timer IC in the monostable mode. As long as normal light is falling on LDR1, its resistance is comparatively low. As a result pin 2 of IC3 is held near Vcc and its output at pin 3 is at low level. In darkness, LDR resistance is very high, which causes pin 2 of IC3 to fall to near ground potential and thus trigger it. As a consequence, output pin 3 goes high during the monostable pulse period, forward biasing transistor T3 which goes into saturation, energising relay RL5. With auto/bypass switch S2 off (in auto mode), the load gets connected to supply via switch S3. If desired, the load may be switched during the day-time by flipping switch S2 to ‘on’ position (manual). Preset VR3 is the sensitivity control used for setting threshold light level at which the load is to be automatically switched on/off. Capacitors with the relays ensure that there is no chattering of the relays. When the mains is present, diode D8 couples the input voltage to regulator IC1 whereas diode D10 feeds the input voltage to it (from battery) in absense of mains supply. Diode D5 connects the load to the power supply section via resistor R5 when mains is available (diode D18 does not conduct). However, when mains power fails, the situation reverses and diode D18 conducts while diode D5 does not conduct. . The load can be any bulb of 12 volts with a maximum current rating of 2 amperes (24 watts). Resistor R5 is supposed to drop approximately 12 volts when the load current flows through it during mains availability . Hence power dissipated in it would almost be equal to the load power. It is therefore desirable to replace R5 with a bulb of similar voltage and wattage as the load so that during mains availability we have more (double) light than when the load is fed from the battery. For setting presets VR1 and VR2, just take out (desolder one end) diodes D7, D10 and D18. Connect a variable source of power supply in place of battery. Set preset VR1 so that battery-high LED D15 is just off at 10.2V of the variable source. Increase the potential of the variable source and observe the shift from LO BAT LED D13 to D15. Now make the voltage of the source 13.5V and set preset VR2 so that relay RL2 just energises. Then decrease the voltage slowly and observe that relay RL2 does not de-energise above 10.2V. At 10.2V, LED D15 should be off and relay RL2 should de-energise while LED D13 should light up. Preset VR3 can be adjusted during evening hours so that the load is ‘on’ during the desired light conditions


Download Circuit Diagram :
http://www.ziddu.com/download/2280897/3.gif.html

Car anti theft wireless alarm

Car anti theft wireless alarm.
This FM radio-controlled anti- theft alarm can be used with any vehicle having 6- to 12-volt DC supply system. The mini VHF, FM transmitter is fitted in the vehicle at night when it is parked in the car porch or car park. The receiver unit with CXA1019, a single IC-based FM radio module, which is freely available in the market at reasonable rate, is kept inside. Receiver is tuned to the transmitter's frequency. When the transmitter is on and the signals are being received by FM radio receiver, no hissing noise is available at the output of receiver. Thus transistor T2 (BC548) does not conduct. This results in the relay driver transistor T3 getting its forward base bias via 10k resistor R5 and the relay gets energised. When an intruder tries to drive the car and takes it a few metres away from the car porch, the radio link between the car (transmitter) and alarm (receiver) is broken. As a result FM radio module gene-rates hissing noise. Hissing AC signals are coupled to relay switching circ- uit via audio transformer. These AC signals are rectified and filtered by diode D1 and capacitor C8, and the resulting positive DC voltage provides a forward bias to transistor T2. Thus transistor T2 conducts, and it pulls the base of relay driver transistor T3 to ground level. The relay thus gets de-activated and the alarm connected via N/C contacts of relay is switched on. If, by chance, the intruder finds out about the wireless alarm and disconnects the transmitter from battery, still remote alarm remains activated because in the absence of signal, the receiver continues to produce hissing noise at its output. So the burglar alarm is fool-proof and highly reliable

Download Circuit Diagram : http://www.ziddu.com/download/2280900/wireleddcarralarm.gif.html

PBS Switch Debouncing Circuit

The 555 circuit can be re-triggered if the input is held low longer than the output pulse. To prevent this happening, I have included a further timing circuit comprised of the 1Meg resistor and 47n capacitor. Normally, the 47n capacitor is discharged via the 1 Meg resistor. When the switch is pressed the capacitor quickly charges and provides a brief negative pulse to the 555 input. When the capacitor is fully charged, the potential across the voltage divider formed by the 10k and 1Meg resistors is insufficient to retrigger the monostable. Releasing the switch quickly discharges the capacitor. The output of a 555 monostable is suitable for connecting to TTL and CMOS logic circuits.

Download Schematic Diagram and Part List :
http://www.ziddu.com/download/2175163/PBSSwitchDebouncingCircuit.pdf.html

Nicad Battery Charger

This simple charger uses a single transistor as a constant current source. The voltage across the pair of 1N4148 diodes biases the base of the BD140 medium power transistor. The base - emitter voltage of the transistor and the forward voltage drop across the diodes are relatively stable. The charging current is approximately 15mA or 45mA with the switch closed. This suits most 1.5V and 9V rechargeable batteries. The transformer should have a secondary rating of 12V ac at 0.5amp, the primary should be 220/240volts for Europe or 120volts ac for North America.

Download Schematic Diagram and Part List :
http://www.ziddu.com/download/2175121/NicadBatteryCharger.pdf.html

Video Amplifier

Download Schematic Diagram and PartList of Video Amplfier

http://www.ziddu.com/download/2174640/Videoamplifier.pdf.html

Traffic Light Project

Traffic Light Project
This project operates red, amber and green LEDs in the
correct sequence for a single UK traffic light. The time
taken for the complete red - red & amber - green - amber
sequence can be varied from about 7s to about 2½
minutes by adjusting the 1M preset. Some amber LEDs
emit light that is almost red so you may prefer to use a
yellow LED. The 555 astable circuit provides clock
pulses for the 4017 counter which has ten outputs (Q0 to
Q9). Each output becomes high in turn as the clock
pulses are received. Appropriate outputs are combined
with diodes to supply the amber and green LEDs. The
red LED is connected to the ÷10 output which is high for
the first 5 counts (Q0-Q4 high), this saves using 5 diodes
for red and simplifies the circuit.

Download Schematic Diagram and Part List :
http://www.ziddu.com/download/2174637/trafficlight.pdf.html

Temperature Switch Project

Temperature Switch Project
This project will provide you an understanding of the use of germanium diode and how it works compared to the more common silicon diode. It works on the principle that as the temperature surrounding the germanium diode increases, the back resistance decreases sharply.
At room temperature, the germanium diode D1 has a typical back resistance of 10K ohm. At this value, the base of transistor Q1 is turned ON, causing transistor Q2 to turn ON as well. When this happens, the base of transistor Q3 is kept to ground causing it to turn OFF hence the buzzer is OFF.
When the temperature of the surrounding increases, the back resistance of the germanium diode D1 decreases sharply causing the base of transistor Q1 to pull down to near ground potential. This cause the transistors Q1 and Q2 to turn OFF. Transistor Q3 is now forward bias through resistor R2 and diode D2. This caused the buzzer to turn ON indicating that the ambient temperature has risen. The sensitivity of the circuit can be adjusted by adjusting variable resistor VR1 and subjecting diode D1 to a temperature that will trigger the buzzer.

Download Schematic Diagram and Partlist :
http://www.ziddu.com/download/2174632/TemperatureSwitchProject.pdf.html

Simple Home Security Monitorin Project

Simple Home Security Monitoring Project
This project is a standalone simple home security monitoring project that will trigger a buzzer when the magnetic contact is opened. Magnetic contacts are usually NC (Normally Closed) and are used on doors and windows. They consists of two parts namely a magnet and a reed switch. When the reed switch is in close proximity to the magnet, the switch will close and vice versa. Usually the magnet is fitted to the door and the reed switch is fitted to the door frame in close proximity to one another such that when the door is closed, the two parts are in close contact and hence the switch is closed. When the door is opened, the magnet will be a distance away from the reed switch and hence the switch will open.

Download Schematic Diagram and part list :

http://www.ziddu.com/download/2174628/SimpleHomeSecurityMonitoringProject.pdf.html

Simple but reliable car battery tester

This circuit uses the popular and easy to find LM3914 IC. This IC is very simple to drive, needs no voltage regulators (it has a built in voltage regulator) and can be powered from almost every source. This circuit is very easy to explain: When the test button is pressed, the Car battery voltage is feed into a high impedance voltage divider. His purpose is to divide 12V to 1,25V (or lower values to lower values). This solution is better than letting the internal voltage regulator set the 12V sample voltage to be feed into the internal voltage divider simply because it cannot regulate 12V when the voltage drops lower (linear regulators only step down). Simply wiring with no adjust, the regulator provides stable 1,25V which is fed into the precision internal resistor cascade to generate sample voltages for the internal comparators. Anyway the default setting let you to measure voltages
between 8 and 12V but you can measure even from 0V to 12V setting the offset trimmer to 0 (but i think that under 9 volt your car would not start). There is a smoothing capacitor (4700uF 16V) it is used to adsorb EMF noise produced from the ignition coil if you are measuring the battery during the engine working. Diesel engines would not need it, but i'm not sure. If you like more a point graph rather than a bar graph simply disconnect pin 9 on the IC (MODE) from power. The calculations are simple (default) For the first comparator the voltage is : 0,833 V corresponding to 8 V * * * * * voltage is : 0,875 V corresponding to 8,4 V ... .. for the last comparator the voltage is : 1,25 V corresponding to 12 V Have fun, learn and don't let you car battery discharge... ;-)

Download Schematic Diagram
http://www.ziddu.com/download/2174626/Simplebutreliablecarbatterytester.pdf.html

Power Failure Alarm Project

Power Failure Alarm Project
This project is a power supply monitoring device that will trigger a buzzer when the mains supply cuts off. At the same time, the light emitting diode will be turned ON. This device is helpful to inform the loss of power supply to some critical installation such as a pump in a fish tank. Once the buzzer sound, one will know that there is a loss of power supply and actions need to be taken to rectify the situation by providing alternative power supply or relocating the installation.
Circuit Description
The circuit shown below consists of a AC relay. If the mains input is 120V AC, use a 120V AC relay. If the mains input is 240V AC, use a 240V AC relay. The relay is a Single Pole Double Throw (SPDT) type where the COM will be connected to NC terminal if it is not energised. Once energised, the COM terminal will be connected to the NO terminal.

Download Schematic Diagram
http://www.ziddu.com/download/2174622/PowerFailureAlarmProject.pdf.html

LED Torch

LED Torch.
A common problem with small torches is the short life-span both of the batteries and the bulb. The average incandescent torch, for instance, consumes around 2 Watts. The LED Torch in Fig. 1 consumes just 24 mW, giving it more than 80 times longer service from 4 AA alkaline batteries (that is, up to one month's continuous service). Although the torchs light output is modest, it is nonetheless quite sufficient to illuminate a pathway for walking.
The LED Torch is based on a 7555 timer running in astable mode (do not use an ordinary 555). A white LED (Maplin order code NR73) produces 400 mcd light output, which, when focussed, can illuminate objects at 30 metres. Try Conrad Electronic for what appears to be a stronger white LED (order code 15 37 45-11).
A convex lens with short focal length is placed in front of the LED to focus the beam. If banding occurs at the beams perimeter, use another very short focal length lens directly in front of the LED to smooth the beam.

Download Schematic Diagram :
http://www.ziddu.com/download/2174612/LEDTorch.pdf.html

Free Hidden Electricity

FREE Hidden Electricity!
This Instructable will show you how to tap into a FREE source of electricity! All you need is a phone line! All phone lines have a constant flow of voltage, around 40-70 volts (up to 100 volts when it rings!), but you can't just plug stuff into it and expect it to work. You can really mess with your phone system by doing that. I discovered how to do it the right way
What You Need...
1. Small project enclosure 2. (1) 240ohm resistor 3. (1) 510ohm resistor 4. (1) LM317L Regulator 5. (1) KBP210 Bridge Rectifier 6. (2) Phone line cables

Download Schematic Diagram :

http://www.ziddu.com/download/2174617/phoneelectricity.pdf.html