Electrinic and circuit

High Current Battery Discharger

If you have a motley collection of 12V batteries in varying states of health, this simple circuit will allow you to easily check their capacity. Its basically a high-current discharge load which is controlled by the NiCd Discharger. This involved increasing the existing 10µF capacitor across LED1 to 100µF, to enable it to supply the brief current pulses required by the clock mechanism. The dischargers "clock connection" now controls a BC457/BD139 Darlington transistor pair (Q1 & Q2) via a 1kO resistor. These in turn activate a car headlamp relay to switch...

Digital Isolation up to 100 Mbits

When it is necessary to send a digital signal between two electrically isolated circuits you would normally choose an optoisolator or some form of transformer coupling. Neither of these solutions is ideal; optocouplers run out of steam beyond about 10 MHz and transformers do not have a good low frequency (in the region of Hertz) response. The company NVE Corporation (www.nve.com) produces a range of coupler devices using an innovative ‘IsoLoop’ technology allowing data rates up to 110 Mbaud. The example shown here uses the IL715 type coupler providing four...

Solar Relay

With extended periods of bright sunshine and warm weather, even relatively large storage batteries in solar-power systems can become rather warm. Consequently, a circuit is usually connected in parallel with the storage battery to either connect a high-power shunt (in order to dissipate the excess solar power in the form of heat) or switch on a ventilation fan via a power FET, whenever the voltage rises above approximately 14.4 V. However, the latter option tends to oscillate, since switching on a powerful 12-V fan motor causes the voltage to drop below...

Solar Battery Protector Prevents excessive Discharge

This circuit prevents the battery in a solar lighting system from being excessively discharged. Its for small systems with less than 100W of lighting, such as several fluorescent lights, although with a higher rated Mosfet at the output, it could switch larger loads. The circuit has two comparators based on an LM393 dual op amp. One monitors the ambient light so that lamps cannot be turned on during the day. The second monitors the battery voltage, to prevent it from being excessively discharged. IC1b monitors the ambient light by virtue of...

Lead Acid Battery Regulator For Solar Panel Systems

The design of solar panel systems with a (lead-acid) buffer battery is normally such that the battery is charged even when there is not much sunshine. This means, however, that when there is plenty of sunshine, a regulator is needed to prevent the battery from being overcharged. Such controls usually arrange for the superfluous energy to be dissipated in a shunt resistance or simply for the solar panels to be short-circuited. It is, of course, an unsatisfactory situation when the energy derived from a very expensive system can, after all , not be used to...