by pinomelean @ instructables.com:
Lithium based batteries are a versatile way of storing energy; they have one of the highest energy density and specific energy(360 to 900 kJ/kg) among rechargeable batteries.
The downside is that, unlike capacitors or other kinds of batteries, they can not be charged by a regular power supply. They need to be charged up to a specific voltage and with limited current, otherwise they turn into potential incendiary bombs.
And that’s no joke, storing such a high amount of energy in a small and normally tight packaged device can be really dangerous.
Li-ion battery charging guide - [Link]
Elmars Ositis has been working on a simple constant current driver:
In my previous post, I slapped together a quick LED lighting solution for my workbench… but it is truly a hack. What I really want to do is make a simple constant current driver, so the power LEDs can be used in other projects. One of those projects is an LED swimming pool light. It needs to be running at maximum brightness and low cost.
After much digging and testing, I found a simple circuit using a power FET, an OP Amp and 0.5 ohm resistor.
This simple circuit accepts a VCC up to 32v (limited by the Op-Amp). The 78L05 regulator provides a stable 5v reference and R1 is a potentiometer serving as a voltage divider, with the output on pin 2 serving as a reference voltage for the basic LM358 Op-Amp.
Simple constant current driver for a high power LED - [Link]
This Arduino Nano controlled solar battery charger can charge a standard lead acid 12V battery and runs with 90% efficiency under 70ᵒC (158ᵒF). The circuit can take up to 24V input from the solar panels. The maximum power point tracking is implemented in the circuit by measuring the output voltage and current from the solar panel to get the maximum possible power from it.
Solar battery charge controller - [Link]
Infrared remote control for home appliances is a popular project among hobbyists and students. Smart Outlet is a similar project that provides an infrared controlled AC outlet to connect any electric appliance and has an integrated timer in it. The appliance can be turned on and off from several feet away using an IR remote. The device is Arduino-controlled and has a LCD display to provide a menu based interface to the user for its operation and settings.
Infra-red controlled smart AC outlet - [Link]
Triac based Indecent lamp dimmer is a simple circuit and it doesn’t requires additional power supply, works directly with 110V AC or 230V AC. It is a low cost dimmer circuit for adjusting the light brightness of incandescent, Halogen Lamp, Light Bulb load up to 250 W.
Triac based lamp dimmer - [Link]
The LT®8310 is a resonant-reset forward converter controller that drives an external low side N-channel MOSFET from an internally regulated 10V supply. The LT8310 features duty mode control to generate a stable, regulated, isolated output using a single power transformer. With the addition of output voltage feedback, via opto-coupler (isolated) or directly wired (nonisolated), current mode regulation is activated, improving output accuracy and load response. A choice of transformer turns ratio makes high step-down or step-up ratios possible without operating at duty cycle extremes.
100 V Forward Voltage Controller - [Link]
A DIY 60W adjustable electrical load project from Electro-Labs:
In this project, we are building a useful board which should take place on your bench. It is an adjustable electrical load which can sink up to 5A @ 60W continuously. This board will come to aid when you need to draw an exact amount of current from a supply. For instance to learn the current rating of a power supply, measure the heat dissipated on a circuit element, discharge a battery etc.
The electrical load lets you monitor the current by using the ampermeter on it. A multiturn variable resistor is used to set the current precisely. The circuit is powered by a 15V-18V power adapter. A large heatsink on the board helps dissipating the heat generated on the MOSFET which is the main component used for limiting the current.
DIY 60W adjustable electrical load - [Link]
Here’s an Instructable about a DIY charger for car’s battery with an analog DC ammeter in the front panel. A PIC12F683-based control circuit is enclosed inside which adds some intelligence to this charger. The PIC MCU checks the terminal voltage of the battery being charged in every ten minutes using one of its analog inputs, and if it is found above a set threshold, the charging process is stopped. A relay switch is included into the circuit to connect/disconnect the charger output and the battery terminals.
PIC12F683 based battery charger - [Link]
Switch-mode regulator Traco TSR 0.5 will give you as much as you need. If you have an application, where 0.5A is sufficient, then the new series of DC/DC modules is ideal for you.
Maybe, it´s worth to ask a question, whether it makes sense to use a switch-mode regulator for such a low current? For sure yes, at least because of two reasons. If we need to create 3.3V from for example 12V, then at a current of 0.5A a power loss of 4.35W appears at a classic linear regulator. That´s already a quite considerable power, able to heat up a device – especially at smaller enclosures and a dense population on a PCB.
Another reason is energy saving – especially at battery powered devices. Switch mode power supplies (SMPS) have a “genial” feature, that thanks to their high efficiency we use practically whole power drawn from a source, i.e. if we need say 5V/0.5A from a 15V source – we won´t take from it 0.5A but only approx. 0,17-0,18A.
Novelty of company Traco Electronic – series TSR 0.5 is by its function very similar to well known, proven DC/DC regulators TSR1 or TSRN1. The main difference is in a smaller allowed current and a feelingly lower price . That ´s why this series is very suitable for any application, where a current of 0.5A will be sufficient. A big advantage can be a wide operating temperatures range from -40 to +90°C (power derating 5%/K at temperature above 80°C). Maximum input voltage of 32V enables a usage even at power supplying from various alternative energy sources with a big input voltage fluctuations.
This novelty is so far available in a version with 5V output voltage (TSR 0.5-2450) and soon there will be another.
Why to pay for the current, which you won’ t use? - [Link]
By Steven Keeping @ digikey.com:
Modular DC-DC switching voltage converters (or voltage regulators) are fully integrated devices that take away most of the complexity of power supply design — but not all. One of the key areas that are still left to the design engineer’s discretion is the choice of components for, and layout of, the energy storage and filtering circuits. In principle, these look like simple circuits comprising a few resistors, capacitors, and the energy-storage element, usually an inductor.
Capacitor Selection is Key to Good Voltage Regulator Design - [Link]