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Battery Level Indicator

This circuit uses a LM339, a quad comparator. LM339 can work on single or dual supplies, it has a open collector output that can drive 15mA, low power consumption. The circuit is an untested design but it should work. I did it as many searches were made in my webpages with these keywords.

Mains Voltage and Power Circuits – Similar circuits for Mains Voltage Monitoring.

There are many better circuits in the various circuit archives i have linked on the front page, you just have to look around. When you measure the open circuit voltage of a battery with a high impedance DMM (10M), the value may be a bit misleading. Apply a dummy load to bleed the battery a bit so that proper readings can be taken on Load. The load below is a 100 ohms wire-wound fusible ceramic resistor which will heat a bit when you test 12V batteries.
Battery Level Indicator

Theory of Operation.

R16 a 5W ceramic wire wound bleeder or dummy load. R15 is a part of an attenuator for obtaining ranges. D2 is a protection clamp diode. R10-D1 forms the 5V reference for comparators. Then an attenuator obtains 1.2, 1.4, 1.6, 1.8 V steps for each comparator. This circuit is similar to Audio Level meter or VU meter circuit.

Comparators in Interface Circuits

The comparator compares the battery sample voltage to the fixed reference step. If ‘+’ pin is more positive than ‘-‘, or is ‘+’ is more dominant, then output goes floating ‘open collector’, so No LED light . But if ‘-‘ is more dominant the output transistor of comparator goes low impedance or saturates or turns ‘ON’. But only spec current can be switched, do not compare with electrical switch ‘ON’. Also on a dual supply 0V is more dominant or positive compared with -12V, even though it appears -12V is a big number. The direction of current is what decides, all measurements are relative.

ThingM – Product and Interface Design

Design and manufacture ubiquitous computing products that combine user experience design expertise with a deep knowledge of cutting-edge technologies. Here, networked electronics meet user experience design in products for everyday problem solving…

ThingM – Product and Interface Design

>BlinkM MaxM” height=”225″ width=”300″/></p>
<p><a href=BlinkM MaxM, is BlinkMs bigger, crazy sibling. It’s an intensely-bright smart LED that comes as a package of two components, a control module (MaxM Master) and a daughter board with three ultrabright LEDs (MaxM Blaster).

Tod E. Kurt co-founder ThingM

Invisible Accent Light with BlinkM MaxM & FreeM

Invisible Accent Light with BlinkM MaxM & FreeM

“Sometimes you just want a little extra light in a room. With RGB LED tape, you can put light anywhere. But controlling its brightness and making it the color you want is a bit harder. A BlinkM MaxM can easily control LED tape, either as a stand-alone device, with an Arduino, or your computer via a LinkM.”

Edison Bulb Life Extender

The Edsion Filament lamp may be less popular, but it is the most cost-effective light even today. It is very affordable, The light is soothing to the eyes and best of all gives a warm feeling.

Edison Bulb Life Extender

Sometimes due to the mains being restored when bulb is on, or a rapid flick of switch, blows it. This may be due to the cold filament resistance which is low, allowing a huge inrush current.

The problem can be solved with a soft start based on thyristor or mosfet using PWM etc. The circuit here is a low cost solution which may help a bit in reducing the inrush cold current Protection from long duration high voltages is also required but will make circuit more complex.

Now why would anyone spend for a R-C network for a bulb, you could as well buy a new bulb. But I once got a back sprain while replacing a bulb in a hurry, So the price of the bulb alone is not the issue.

The two diodes 1A form a AC path with a switching delay of diodes, The R-C network is for soft start. The Varistor-Thermistor has a cold resistance 4.7E which reduces as it warms up. If switch is flicked rapidly or power fluctuates, then varistor cannot help as its response is slow. The 10E resistor ceramic fusible wirewound resistor and C1 does the job of absorbing .

This circuit has not been tested for long times at multiple places, so i am not sure of its performance.

Perpandle improved with Pepper Cap and Knob

Once upon a time i heard a story of pepper and pyramids. From that i concluded that the Gargantuan Pyramids were not built by punishment but by reward. This was the main Economic Activity of the Ancient World. It kept many people busy in those days, even today it supports an entire industry and makes tourists ecstatic and nostalgic.

The secret of Management of Ancient Egypt was Pepper, The other Technique, Whipping just did not work (it probably increased Healthcare costs). Pepper made them work harder and even the Pharaoh remained in his cubicle/cabin a few hours more. Pepper became the currency, this lead to The “Pepper Standard”.

In the Perpandle (Perpetual Candle) below, A cap from a Salt/Pepper Set had to be used in this upgrade. This Peppering is dedicated to the Egyptians who worshiped the Sun. They knew one day we all will depend on Solar Energy.

The Pharaohs and their Administrative Team displayed rare Genius. Not only they created employment opportunities in that era, but also made a Pension Plan for the descendants of that Ancient Land. It’s working even today.

The foundation is a Gaming Joystick, the Center piece is a bamboo tube. The bottom of this pipe is a brass part. A autotransformer dial is the big washer. The LEDs on both sides of a PCB in a Translucent Plastic Measurement Cup which comes with Vitamin Tonics. The second version the LEDs and Resistors was built into an Acrylic Like Transparent Salt/Pepper Spherical cap. On it was mounted a Transparent cupboard knob, giving it that exotic Byzantine look.

Perpetual Candle Project moves onward. Completes One Year only with Aesthetic Fixes. No Electronic Failures as it uses Ni-Cd Batteries and sensible conservative design.

LED Lamp or Bulb with Flashlight option

This is another LED lamp from China a firm called Hoya, these people make nice lamps and also good designs of the plastic enclosure. Here by a clever enclosure design it is both a emergency mains bulb and Torch/Flashlight.

The price is low and they use a small sealed lead-acid battery worth 4.5 V and around 1 AHr. That means it could give an hour of performance at 1 A drain/usage. The voltage by the elapsed hour could be near 4. Here the battery failed, vibration or leakage; OR combination of both. The acid, very little or even corrosive vapor has eaten the copper wire of positive wire/junction. The Cut Red wire, broke circuit equilibrium and burnt the R? = 3.3K – 4.7k ?. The lamp failed all other parts intact.

From Schoodles

How it works ?

It uses a step-down cap, this is very tricky. It has to be a HV cap overrated and excellent quality. These caps not good enough. I am partially responsible for this cap idea spreading around. It was decades ago in relation to bringing down the cost of industrial. automation timers. The transformer had to go and smps solution too much; a resistor inefficient. I was triggered by the choke used in tubelights to bring down voltage after firing. So if L can be used, then even C for low currents, no heat wasted. The timer worked, successful sales. Idea/Concept became popular. This idea also misused by others to save cost. This design needs an Axial Polycarbonate/Polypropylene 630V/1KV cap for reliable operation.

Now this 18 LED array, has no current limit, is it not quite a problem. The chinese are innovative on saving cost, here its fine, but.many times we can sacrifice quality. In this design the LEDs drop around 3.3V and the Transistor 1 Volt as it is not driven to saturation. On full load the battery also deregulates, so it does manage to save itself. This transistor also serves as a mains detector along with the 1N4148. On mains failure the LED lamp turns on Automatically.

Another Lamp had a Burst out 100uF cap this means, surges or spikes are damaging the 1uF 400V Plastic cap used for current limit.

Recommendations to such Lamp Designers

Use Metalized Polypropylene MPP – rated for 440V AC continuous working. That means it must be rated like a Power Factor correction/saving capacitor. It may mean 1KV DC operation.

  • Use an Axial 1uF polypropylene 630V DC or 440V AC Capacitor
  • Sell it with a Marketing Advantage as Power Factor Compensation.
  • Use two 2.2uF 630V DC Axial MPP, one on Live and the other on Neutral.

A house using Motors and Fans will have inductive elements, even tubelights that have chokes 50/60 Hz kind. This is compensated by capacitive loads. So each of these Capacitor LED lamps can be a Green Lighting and PF compensator.

LED Lamp – Simple Bed-Lamp Circuit

LED Night lamp, Clock Lamp to see time at night. It is a Green Lamp just 50mA, but its Blue in Color.

From Schoodles

This can be a first LED Lighting project anybody can do. Just twist wire, use insulation tape. Get a Nice Mains adapter that will provide 6V DC. 5V also will do. A prior Knowledge of Ohm’s law is essential.

LED’s are used as Indicators, Annunciations and now for Lighting. When i used to make gadgets, there was only Red, Yellow and Green and nothing In-between.

Now we have Blue ! and White as in Flashlight and probably much more like Oled and LED Monitors and TV. Here are some Old and New Schoodles of mine. Schoodle is a Schematic Doodle. Another English word from dapj Tech. My earlier Word and Acronym Creations have never been credited, please don’t miss this time. Don’t credit the Idea Squirrels.