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This electronic circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch can be moved from within the house which will light a lamp in the door bell switch. The lamp can illuminate the words "Please Wait" for anyone with walking difficulties. Simple Doorbell for the Deaf Circuit Diagram: Notes The circuit uses standard 2 wire doorbell cable or loudspeaker wire. In parallel with the doorbell switch, S1, is a 1N4001 diode and a 12 volt 60mA bulb. The bulb is optional, it may be useful for anyone who is slow to answer the door, all you need to do is flick a switch inside the house, and the bulb will illuminate a label saying Please Wait inside the doorbell switch or close to it. The double pole double throw switch sends the doorbell supply to the lamp, the 22 ohm resistor is there to reduce current flow, should the doorbell switch, S1 be pressed while the lamp is on. The resistor needs to be rated 10 watts, the 0.5 Amp fuse prot...

Finding the best amplifier for your auto sound system can be a lot easier if you take the time ahead of time to learn what you need and what will work best with the sound system you've selected for your car, truck, or SUV. It helps to understand what an amplifier does in order to purchase the one that will best suit your needs. An amplifier takes a small sound, adds a little boost of its own, and then turns it into a big sound. The more power your amplifier has, the better quality of sound it will provide. An underpowered amplifier will have a thin, tinny sound that is rather unattractive in an auto sound system, or any other sound system for that matter. You should also take care to remember that the power rating of an amplifier is the maximum power it is capable of expending not the amount that it will regularly use. The RMS rating of an amplifier is a good indication of its power output. One thing that is important to remember is that you should never buy an amplifier based on t...