Rechargeable NiCd (nickel-cadmium) cells are widely used in consumer devices because of their high energy density, long life, and small self-discharge rate. As a part of one project, I needed to design a reliable and inexpensive charger for a battery pack containing two NiCd AA-size 1200-mAh cells. In the process of the charger design, I […]
Charge a nickel-cadmium cell reliably and inexpensively Read More »
Properly maintained rechargeable batteries can provide good service and long life. Maintenance involves regular monitoring of battery voltage. The circuit in Figure 1 works in most rechargeable batteries. It comprises a reference LED, LEDREF, which operates at a constant current of 1 mA and provides reference light of constant intensity regardless of battery voltage. It
Simple battery-status indicator uses two LEDs Read More »
Aurora 48 is capable of individually controlling 48 Full color LEDs using a 40 pin microcontroller. The principle of operation is based on my other “Aurora”s. (see Aurora 9×18) The circuit is relatively simple and straightforward. If you’ve seen other LED matrix type circuit, this should look familier. In a nutshell, the 48 RGB LEDs are divided in two
Aurora 48 – 48 RGB LED Sequencer Read More »
A circuit that properly charges sealed lead-acid batteries ensures long, trouble-free service. Fig 1 is one such circuit; it provides the correct temperature-compensated charge voltage for batteries having from one to as many as 12 cells, regardless of the number of cells being charged. The Fig 1 circuit furnishes an initial charging voltage of 2.5V
Charger extends lead-acid-battery life Read More »
This voltage monitor has been designed to remotely display battery voltage so that people monitor and maintain their batteries easily. It was designed for use on off-grid reneable energy systems (such as my solar PV system), but it would also be useful to anyone who has a lead-acid battery, such as caravans, boats and cars.
Battery voltage monitor Read More »
Yesterday I saw the “The Practical Meter” on Kickstarter – a small unit that is placed inline with the USB when charging your phone and shows the actual charging power (in watts) on a row of LEDs. I wanted to have a go at it as well so I did the following last evening. First
PAW17 – USB Spypow Read More »
A TL431 shunt regulator is a perfect choice for many applications. You can use it as a comparator with hysteresis by taking advantage of its inner voltage reference along with few additional components. You can use this comparator with hysteresis, like a Schmitt trigger, as a simple battery monitor (Figure 1). You calculate the threshold
Shunt regulator monitors battery voltage Read More »
Like other simple, single-cell lithium-ion battery chargers, Microchip’s MCP73812 provides no means of indicating the charging status. You can remedy this situation by adding four components (Figure 1). Add one more LED, and you also get a charging-complete indication. This two-LED configuration has the added benefit that one of the LEDs is always on, providing
Add charging status to simple lithium-ion charger Read More »
Waveform generators (also called function generators) are useful for testing and debugging circuits. They can be used to test the frequency response of electronic components like op amps and sensors or to characterize and troubleshoot audio effects boxes and pedals. This waveform generator shield is powered by an Arduino. It outputs four waveforms: sine, triangle,
Arduino Waveform Generator Shield Read More »
Occupying a footprint of just 2.57×3.24 mm, the STA333IS single-chip digital audio system from STMicroelectronics furnishes up to 20 W of audio output power for use in space-constrained LCD and LED televisions, docking stations, and digital wireless speaker systems. With is wide operating voltage range of 4.5 V to 18 V, the device is also
Tiny digital audio SoC delivers up to 20 W Read More »
