Merry Christmas & Happy New Year 2009
I'd like to take this time to wish all of you a very Merry Christmas.
This is a season of giving, peace, understanding and goodwill among all. I hope that this Christmas will find you among friends and family with good food, good times, and good memories. And I hope too that Santa lines the bottom of your Christmas tree with all the Amateur Radio goodies that it can hold!
Wish you a very happy new year, many nice DX contacts, a lot of pleasure with our hobby and see You in 2009 again!
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How to measure accu voltage |
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The life of accu cells is depending on the style of use. Not proper accu discharning and charging is a short way to destroy them. Many amateur transceivers are able to work also on low voltage except the accumulator is fully discharged. So how to measure the voltage without voltmeter or multimeter on portable?
Simple indicators are showing only two states – charged and discharged. This is not enough to plan operation and early know when is accumlator low. Described indicator is measuring voltage in 5-steps, it's easy to build and cheap.
How it works? It's a cascade of LED diodes. When is accumulator fully charged are lightening all LED diodes. When is the voltage going down, the highest LED doesn't have enough voltage to light. For the last time is lightening only one LED diode. Every step is 0.3 – 0.8V (depending on the diode type). Zener diode is used to reduce a scale of measurement.
I haven't exactly say which diodes (D) are suitable for us. Available are silicon diodes (0.8V step), Schottky's diodes (0.4V) and germanium diodes (0.35V). For example, with Schottky diodes will LED diodes light at 10.5 – 10.9 – 11.3 – 11.7 –12.1 (or more) V.
To differentiate the state of accu could be used few colours of LED diodes. Fully charged accu may representate green LED diodes, medium discharged accu yellow LED diodes and the last diode could be red.
The circuit can be combined with other circuits that are reuired with portable operation, e.g. turnover protection. The switch S is used to keep consumtion low.
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