Imagine a situation. We are going for a night drive and stopped the car in a place for some purpose. Then we see that the car is not starting because the battery is flat. It is a totally confusing situation. We will be trapped if this happens in an isolated place. The only way is to leave the car there or wait till morning to purchase a new battery. Don’t worry. Keep a ‘Jump Starter’ always in the car. It will start the car in 5 minutes. Many Jump starters are available in the market but the cost is too high. We can easily make a Jump Starter using a UPS battery. How the Jump starter starts a car if its battery is flat? Actually, the Jump starter has a 12 volt battery inside. When we connect this new 12V battery across the flat car battery, the new battery shares its current to the flat battery. After 5-10 minutes, the terminal voltage of the flat car battery increases to 12.6 volts. It is sufficient to start the car. Jump starter is the improvisation of the conventional technique of connecting the flat battery of one car across the battery of another car using battery clips and wires .That is why the technique is called as “Jumper starting” or simply “Jump starting”. Now light weight Power bank type Jump starters are available with 10,000 to 15000 mAh Lithium Ion battery. These have provisions like Mobile charger, LED light, Distress signal light etc. But the cost is very high around Rs.6000- 10,000. Let us make one Jump Starter with the same provisions like Mobile charger and LED light. The Jump starter can be charged from the Lighter socket of the Car. Its cost is less than Rs.800. Continue reading →
Why going for a costly Fire Alarm system? Some of the Fire alarm systems cost more than Rs.2000. You can make an efficient Fire warning system for just Rs.20. It uses only a few components and is a very efficient Flame sensor. The Thermister based commercial Flame sensors have a drawback because, the alarm sounds only when the Thermister turns hot by the nearby flame. That means, the alarm sounds only after the room is full of fire. But this tiny circuit overrides that drawback. It uses a Photodiode as Fire sensor. It sounds the alarm even if the flame is far away . Interestingly, the spark of the first fire burst can activates the alarm. It can be installed in Home, Commercial shops etc. It will not activate in the ambient light of the room like that of Fluorescent light. It sounds the alarm only when it detects a light similar to a flame, sunlight or incandescent bulb. It is battery operated and in the standby state the current consumption is as low as 5 mA. So Simple, Efficient, and Low cost. Build it. Continue reading →
I found that my UPS is not giving sufficient back up as expected for 20 minutes. I thought that I have to spend Rs. 800 to replace the battery. But I was not in a hurry. Want to find out the reason. After 5 minutes, the PC shutdowns. Why so? The UPS battery is not giving sufficient power (Ampere Hour) to run the load. The UPS battery is a 12 volt7 Ah (Ampere hour) Maintenance free Sealed Lead – Acidbattery (SLA). That means, it is “Maintenance free” and can be used for long time without any attention. But what happens is, the cells dry out due to heat generation. This happens after 6 months to 1 year of use . It is a Lead Acid battery that requires Electrolyte in the cells. So water is necessary inside. It has 6 individual cells giving 2V each. After removing the battery from the UPS, I found that it is very easy to rejuvenate the battery through “Hydration”. The battery will become top, if the dry cells are filled with battery water. Hydrated the battery and charged. Well, now it is giving more than 15 minutes back up. Saved Rs. 800 and reduced an e-waste. You can also rejuvenate the 6V Emergency lamp battery like this. So do it yourself. It is only a 10 minutes job.
One Damaged Mosquito Swatterwas in my home with full of dust. So, decided to salvage its parts to reuse for other purposes. Just to avoid e –waste and to do some kind of Recycling. Well, it has a good 2.4VRechargeable Battery and a circuit board. The problem is in its circuit board that generates highvolt AC to burn the Mosquito. But the charger is still working. So decided to use the charger part to make a High power Rechargeable LED Flash light. The Mosquito Swatter generates a high voltage between 400- 1000 volts from the 2.4 V battery. For this, there is an oscillator circuit and an Inverter transformer. The Inverter transformer converts the 2.4 V DC from the battery to around 200V AC. The oscillator circuit makes the AC waveform. The 200 V AC thus produced is then boosted by a Voltage Multiplier comprising some high volt capacitors and diodes. This boosted AC appears in a High volt Capacitor which then passes it to the Nets of the Swatter. The middle net of the Swatter is Positive while the outside nets are Negative. When we press the switch, the High volt capacitor discharges high volt AC to the nets. When the Mosquito passes through the net, it explodes due to high voltage. Even though the AC voltage is very high around 1KV, Current is negligible. Let us see how that Swatter turned into a Rechargeable Flash light. Continue reading →
Wow! We can make a cup of cold water in 5 minutes without a Fridge. You need only a Peltier Element, a 12 volt high current battery and a Computer cooling fan. Peltier element is a semiconductor plate like device with Cold and Hot sides. When we provide 12 -18V, 1 amps power to it, one side of the Peltier suddenly cools and the other side turns hot. The cool side temperature goes down below 0 degree and the hot side becomes around 100 degree. So to transfer that much heat, the Peltier should be placed over a large Heat sink. A Computer cooling fan with heat sink is the best choice. Fan will remove the heat from the Peltier and heat sink. At the same time, the cold side turns too cool in minutes. Without a heat sink, the Peltier will be damaged. If we reverse the Polarity (+ and –) of the power supply to Peltier, the sides reverses. That means, cool side becomes hot side and vice versa. Let us make one Peltier Fridge to get some cold water. Later we can change it as a heater to drink hot water. Peltier costs around Rs.200. Continue reading →
Thwart the attempt of a Bag snatching during journey. Keep this Tiny Alarm in your bag and it will beep loudly when somebody attempts to snatch your bag. It can protect your Laptop bag, Mobile pouch, Luggage etc during the journey. It is essentially a “Vibration Alarm” using ultra sensitive Vibration sensor SW 18020 P. So even a mild shake can activate the alarm. Build it and its cost is just Rs.50. Continue reading →
You can make a beautiful Rainbow display to decorate your show case to give a “Visual Treat “to the visitors. It emits all the colours of the Rainbow (VIBGYOR) one by one and finally flashes rapidly. This is a kind of simple “Mood Lamp” to elevate the mind of viewers. You can fix it in an empty Jam pot so that it appears like a “Rainbow pillar”. A Multi colour Flashing LED and Glue stick can do this Magic. Multicolour LED has three chips to generate Red, Blue and Green (RBG LED) lights. Due to the fast transition of colours from one to another, the colour mixes and gives the Rainbow display. The Gluestick commonly used with the Glue gun transmits this light to its entire length giving a good visual effect. So try it, you need only Rs.25 for this. Continue reading →