JN Lygouras, University of Thrace writes:
The control circuit in Figure 1a allows you to manually adjust the power delivered to a load. By changing the setting of potentiometer R3, you change the phase angle at which the thyristor (Q3) fires (Figure 1b), thereby altering the load current’s duty cycle. The adjustment range is about 0 to 180°. Q3’s off time is linear with R3, but of course the resulting load power is not linear with R3.
555 timer triggers phase-control circuit - [Link]
Battery-Charging Controllers for Energy Harvesters by Jon Gabay:
Whether your energy harvesting application uses large solar panels with high voltages and currents or, more often the case, must make do with minute amounts of power derived from various other ambient energy sources, one thing is almost certain: some type of energy storage is on board, whether in the form of a small rechargeable lithium ion battery, a supercapacitor, or solid-state energy storage technology. For the engineer this means that not only do we need to design circuits to harvest and convert ambient energy, but we also have to include an energy-harvesting interface (and protection circuitry) as well as a charge controller. This article looks at single chip energy harvesting devices that also provide some form of charge control. It discusses the different conditions under which energy can be extracted as well as what to expect when trying to squeeze power out of the ambient environment. Finally, the article will present some typical integrated solutions for small-sized low-power energy-harvesting designs.
Battery-Charging Controllers for Energy Harvesters - [Link]
Publitek European Editors writes:
Many security and motion detector systems rely on small, semi-autonomous nodes that are easy and simple to install. This implies the use of a battery-based power source and low-power operation in order to minimize the number of battery changes during the lifetime of the product.
Over its lifetime, the output voltage of a battery falls, with the biggest decline when the charge is nearing full depletion. A converter type that can accommodate this change in voltage but can still provide relatively high voltages for sensors and RF transmitters is the buck-boost converter – it operates the buck part of the circuit when the battery is fresh, moving to boost operation when the voltage falls below the threshold of the electronic circuitry it powers. A number of vendors have developed integrated buck-boost converters optimized for battery systems
Buck-Boost Converters Help Extend Battery Life for Motion Detection - [Link]
TI’s latest Power Management devices, design tools and support resources in the new 2013 Power Management Guide
TI’s Power Management Guide 2013 edition - [Link]
This DC-DC Converter start-up from as low as 330mV input! Marian Stofka writes:
The bq25504 from Texas Instruments is a good candidate to become a milestone on the road to micro-power management and energy harvesting. A prominent feature of this IC is its ability to start up at a supply voltage as low as 330 mV typically, and 450 mV guaranteed. With an SMD inductor and a few capacitors and resistors, it forms a dc-dc converter with a high power efficiency that is unprecedented, especially in the ultralow-power region.
DC-DC converter starts up and operates from a single photocell - [Link]
mic @ wemakethings.net writes:
For a long time I wanted to enter the 21st century by stopping using NiCad or NiMH batteries and upgrading to Lithium accumulators as they provide more power per volume and are cool in general. Constant flow of obsolete cell phones provides a nice source of reasonably high-performance batteries for free – I felt compelled to tap into this resource for my battery operated projects.
Open source Lithium battery charger modules - [Link]
Kennith needed a 1A constant current lead-acid battery charger for his HAM radios so he writes:
Since the SLAs are relatively small, and I only need them charged between radio outings, I opted to build a 1A constant current charger, based on the 555 Battery Charger which won first place in the 555 Design Contest Utility category. Using a 555 is a rather clever way to get two comparators and a Set-Reset latch in a single 8DIP package, which is needed for the high and low trip points. The major difference between my design and Mike’s is that instead of using a relay like him, I use an LM317 as a constant current source to limit my batteries charge rate.
555 based constant current lead-acid battery charger - [Link]
Fully autonomous processors add simple, utility-grade energy measurement and diagnostics to existing designs.
San Jose, CA—January 16, 2013—Maxim Integrated Products, Inc. (NASDAQ: MXIM) today announced that it is now sampling the 78M6610+PSU/78M6610+LMU single-phase energy-measurement processors. These processors are an energy-measurement subsystem in a single chip. They provide simple utility-grade sensing and diagnostics for existing designs without the traditional cost of a utility meter system-on-chip. Both devices contain unique firmware to meet end application requirements. The 78M6610+PSU is specifically designed for real-time monitoring of data centers, servers, and telecom and data equipment, while the 78M6610+LMU is a more general-purpose solution for applications such as white-good appliances, smart plugs, EV chargers, and solar inverters.
The 78M6610 processors enable energy-measurement functionality while reducing both manufacturing costs and time to market. Energy-measurement solutions traditionally required the use of an additional microcontroller, which adds significant design cost and months of development time. The 78M6610 allow users to conveniently add a complete energy meter to an already existing design without significant cost or redesign. Additionally, the processors’ flexible measurement and host interfaces allow for easy integration into any system.
Single-Phase Energy-Measurement Processors Accurately Monitor Power at a Fraction of the Cost - [Link]
With the new AIR 40 wind turbine it is possible to gain 40 kWh monthly – easily and safely.
Advantages / Features:
- high quality wind turbine with 12, 24 or 48V output voltage
- 40 kWh monthly at an average wind speed of 5.8 m/sec
- operation at 3.1-22 m/s wind speeds
- microprocessor based controller
- aluminium body
- composite blades optimized for a quiet operation
- 1.17m rotor diameter
- electronic overspeed protection
- brushless alternator (dynamo) with a long lifetime
Small wind turbines are an excellent electric energy source for all „off-grid“ applications with a low and middle power consumption like telecommunications, lighting, SCADA (telemetry) and other. In comparison to photovoltaic panels, they require only a very simple installation – to tighten to a shaft.
AIR 40 are top quality microprocessor controlled wind turbines with a precise mechanical construction. Thanks to a low weight and an integrated controller, they´re easy to install and provide an energy right after the installation. Composite blades are optimized for a quiet operation, durability and a maximum power in a wide range of wind speeds. A big advantage of Air 40 is a relatively low start-up wind speed – already from – 3.1 m/s. „The heart” of AIR 40 is a brushless alternator dynamo with permanent magnets and with a long lifetime.
Output power of AIR 40 depends from real on-site conditions, however in average it is able to provide 40 kWh monthly, at an average wind speed of 5,8 m/s (21km/h). At higher wind speeds it can be even substantially more. Wind turbines are capable of a standalone operation and they´re also a well-proven complement of PV panels, where they conveniently supplement a decreased power of PV panels, especially in winter season.
Detailed information will provide you the AIR 40 datasheet. In case of interest, please contact us at firstname.lastname@example.org.
Catch the wind into a net (or into a battery) - [Link]
The LT®3651-8.2/LT3651-8.4 are 2-cell, 4A Li-Ion/Polymer battery chargers that operate over a 9V to 32V input voltage range. An efficient monolithic average current mode synchronous switching regulator provides constant current, constant voltage charging with programmable maximum charge current. A charging cycle starts with battery insertion or when the battery voltage drops 2.5% below the float voltage. Charger termination is selectable as either charge current or internal safety timer timeout. Charge current termination occurs when the charge current falls to one-tenth the programmed maximum current (C/10). Timer based termination is typically set to three hours and is user programmable (charging continues below C/10 until timeout).
LT3651-8.2 and 8.4 – Monolithic 4A High Voltage 2-Cell Li-Ion Battery Charger – [Link]