Free Circuit Diagram

Electroscope is a device that is used to detect electrostatic charges. Operation: To reduce AC noise this circuit uses C1, but it will lower the sensitivity a bit. As a voltage divider we use the MPF102 and R1. The divider’s output will be about 4.5V diving a half-scale reading on M1, a 200-uA [...]

By detecting a voltage drop in resistor connected in series with the battery, we can measure the current flowing in or out  of the battery. A simple differential amplifier do that, but we need both positive supply and negative supply to sense the current in both direction,  the current when charging and discharging the battery. [...]

A DC-to-DC step-up converter is traditionally implemented using transformer, working by converting the DC voltage to AC Voltage, step-up it using transformer, then rectify and filter the transformer’s output to  get a higher DC voltage. Using a switching method, we can step-up a voltage without a transformer. We just need an inductor which is driven [...]

More efficient lead acid battery charger can be implemented using switch mode circuit. A switch mode for lead acid battery charger can be constructed using bq24105 battery charger controller. The bq24105 was originally designed to charge single-, two- or three-cell Li-ion and Li-polymer battery packs. Its features doesn’t include the control for lead acid battery [...]

This circuit is used to prevent the damaging effects of a reversed-polarity battery or short-circuit load. It is used to replace the simple fuse that usually used for overcurrent protection because the fuse has long reaction time and high resistance. This circuit consist of dual comparator, a combination of current amplifier, and external CMOS. A [...]

A constant-current/constant-voltage linear charger for single-cell lithium-ion (li-ion) can be constructed using only a tiny battery charger controller chip EUP8054 and a few passive components. This tiny integrated circuit chip is suitable for various portable devices. This controller chip is also compatible with USB power specification, ideal for charging the battery when the device is [...]