Transformer is used to convert high volt AC to low volt AC (Step down) or low volt AC to high volt AC (Step up). So step-down transformer is generally used to convert 230 Volt AC to low volt AC which can be used to make a DC power supply after rectification and smoothing. But a Non polarized capacitor can act like a transformer to step down the high volt AC to low volt AC. Say, 230 V AC to 40 VAC. Let us see how the capacitor is doing this.
Continue reading “How Capacitor functions as a Transformer? Design Note 42”
To reduce size, and cost, Transformer less power supply is now used. If it is a well regulated SMPS power supply, output will be stable. But simple Transformer less power supply is not ideal for many circuits as observed in my experience. I have designed different types of Transformer less power supply but none of them is showing good performance. It can be used to power simple circuits like LED lighting. If sensitive semiconductors are present in the circuit, this kind of power supply creates many problems including erratic response. This is very high in sensor based circuits and oscillators. So to get a perfect output voltage, it is ideal to use a Transformer based power supply or SMPS. These are the problems I noticed in the Transformer less power supply.
Continue reading “Transformer less Power supply Problems. Design Note 39”
It was a big problem in my house that, sometimes the Water heater left on for many hours after the use. It has a Thermostat to cut off but when the water cools, again it switches on. This caused a hike in electricity bill. Finally I found a solution. Just connected a Timer based alarm with the heater AC socket so that it will also switches on when the heater turns on. After 30 minute, it gives a loud alarm to remind that the heater is On. Alarm continues for another 30 minutes or till the heater is switched off.
Continue reading “Alarm for Water Heater”
This Mini portable White LED Emergency Lamp is highly useful in the event of an unexpected power failure. It gives sufficient light in the room. It is too small and is an ideal utility gadget for the use in camp places during journey. It can be plugged in just like a Mobile charger.
About 8566 readers of this Blog visited the transformer less power supply article posted and there are queries regarding the design of the circuit to power different types of gadgets. So one more circuit is posted here that can give 12 volt DC at 300 milli amperes current. This circuit uses AC capacitor to drop the AC power to generate 12 volt DC.