USB Meter - For Measuring Capacity of a USB Power Bank & Other 5V Devices

You have bought a power bank and are wondering if it really measures up to the advertised Capacity?

Check with this Power Meter.

You can connect it to any USB Power Source like your Power Bank.It will Show you the Output Voltage of the Power Bank - This should be 5VOn the USB Female side you connect your Load.You can then see the Current that the Device Consumes.Leave it on for a while and it can give you an indication of the Power Consumed.  This is also the Power delivered by the source (Could be your Power Bank)
It measures Voltage & Current - Power = Voltage x Current (For DC Voltages like this one)
The Total Energy that can be delivered by your Power Bank = The Capacity of your Power Bank.
Energy (Or Capacity) is the ability for the Power Bank to give X Watts for T Time before it runs out of juice.
Hence TIME is the factor that comes into play to measure the Total Energy that can be delivered by your Power Bank or The Capacity of your Power Bank

Capacity = Total Energy that y…

Simple Ideas, Simple Electronics, Useful Products

Posting after a long gap.  I have resolved to post regularly with Simple Electronic Circuits, Product Ideas and general learning resources.  Occasionally I will post links to articles and news items related to Technology.

Iot & Solar Energy Harvesting


Journey towards Making the Most Efficient Garden / Pathway Light

When I first started with Solar Lighting it was to create a simple robust street light.
Created a Light that was good and robust. It was a typical Solar Street Light.
The LEDs were superflux capable of being driven to 50mA - The cooling was provided by the four leads and the PCB was made with lots of copper area to dissipate the little heat.
The design as based around a PIC micro-controller and the output was switching via the controller.
This was in 2005.

Since then I have tried various designs in lighting streets, gardens, porches and pathways.

I am on track to now make one of the most efficient lighting for Gardens, Walkways, pathways and porch lighting.

What do I want in my Android Phone?

Big Screen, more RAM, Stock Android or Good Camera - What are my priorities. So here goes a list of items that one should check out and the reasons for doing the same

4.5 inch is about the minimum required today for a decent experience with Social media, emails and light reading. (A 4 inch one is a heavy compromise)
5 Inch is the minimum for people who do a lot of reading online - This is also the ideal size for a compromise between handling ability and readability.
5.5 Inch is the ideal size for reading (most kindle models are 6 inch). But this is a little big for single handed reading.

With the kind of apps being released and the frequent updates, 1 MB is minimum

Some important apps do not work with anything below 4.2 And a few require 4.4 (kitkat) - So I would suggest kitkat at the minimum.
Stock Android is your best bet - Since this is more of a dream, the version that has the minimum bloatware should be ok.
Update: Marshmallow (6.0) is out and it is really goo…

Solar Thermal

At home we need Hot water for bathing and washing.
Industries require hot water for various processes including space heating and climate control.

Solar Hot water systems are the best choice for domestic as well as industrial use.  They are more efficient when compared with Solar PV in converting the suns energy into useable energy.

A typical Domestic hot water system consists of a Solar Thermal Panel (1, 2, 3 or even 4 panels are used for a single system).  The other important component is the Solar Tank.  This is where hot water is stored.  It is thermally insulated and is the equivalent of a Battery in a PV system.

Although there are two basic types of Panels - Evacuated tube type & Flat Plate type - the Flat Plate Collector is more commonly used.

Each Panel is approximately 2 square Metres.
It generates the equivalent of 5 KWh of electricity on a typical Sunny day in most parts of India.  (The generation will vary by geography & season).
If we compare this with a 2 square metres …

Low Voltage DC Lighting

12V DC & 24V DC LED lights LED Lights that can work off a Standard Car battery is an attractive proposition.  We have created a few designs on 12V as well as 24V DC.

It is important that LEDs are driven with a constant current.  An LED is a current driven device. That is it will light up to its given intensity when the rated current flows through it.  Its colour rendition will also be specified at that current.

Anything above or below the rated current two things will happen.
The intensity will change, as will be the efficacy i.e. lumens/wattThe Colour temperature will shift and you may not get the white light that you expect. What is the role of voltage?
Once you ensure a constant current (we will see how we can achieve that later), we can then measure the voltage across the terminals of the LED.  This voltage should be in a range specified by the manufacturer.  For White LEDs it is usually in the range of 2.9 to 3.5 Volts.  Whatever the current you deliver this voltage will remain…