TREE

This is a circuit for a battery charger with automatic overload protection feature . The power supply is 9V and is stabilized by a voltage regulator IC LM317 . The regulator output is used to charge the 6V battery . Once the battery is fully charged (ie the voltage across the battery is 6V ) enters the zener diode biased and starts conducting , which gives a positive voltage to the base terminal of BC548   loading.  Battery Charger with Protection Circuit Diagram

This is a simple Project of Nicad Battery Protection Circuit Diagram. If a NiCad battery is discharged to a point at which the lowest capacity cell becomes fully discharged and reverses polarity, that cell will usually short internally and become unusable.  To prevent this type of damage, this circuit detects a one-cell drop of 1.25 V and turns the load off before cell reversal can occur. Low-current zener or other voltage sensor Dl and resistors Rl and R2 establish a reference level for transistor Ql. These resistors bias the zener to a few microamperes above its `knee.` Therefore, if battery voltage falls more than 1.25 V, Ql turns off, turning off Q2, and disconnecting the load.   Nicad Battery Protection Circuit Diagram After the load is disconnected, if the battery returns to nominal voltage, the high value of resistor shunting Q2 provides enough output voltage to reset the voltage sensor and turn Q2 back on. If desirable, shunt diode D2 or the parasitic diode of the...

Vehicle immobilisers are fitted as standard to modern cars and heavy goods vehicles. Anti-theft mechanisms have become more sophisticated but so have the methods employed by crooks. Nowadays once the thief has gained access to a vehicle they will most likely use an electronic deactivation tool which seeks to disable the immobiliser, once this has been accomplished a blank transponder key/card can be used to start the engine. In many cases communication with the immobiliser is made using the OBD-II diagnostic connector. Although the OBD-II protocol itself does not support the immobiliser, the vehicle manufacturer is free to use the interface as neces-sary for communication, either the standard OBD-II signals or unused pins in the OBD-II connector (i.e. those undefined in the OBD-II standard). Using one of these pathways the immobiliser can usually be electronically disabled. OBD Vehicle Protection Circuit Diagram This may be unsettling news for owners of expensive vehicles but when...

RF amplifier protection I have developed the protection circuit for the EB104 amplifier I am working on, after I finally had some time to design and test a few models. The main requirements have been: - protection in case of high temperature; - protection in case of high SWR; - protection in case of wrong output filter selection; - simple design (i’m a fan of the whole K.I.S.S. rule of thought), able to work in strong electromagnetic fields, reliable, inexpensive. Because i will be using the same directional coupler i have used in the SWR meter (the one made on PCB) wich is directly influenced by the signal frequency, and because i want full HF coverage, i cannot just measure the reflected signal and make a circuit cut the amplifier when it goes over a limit; on 28Mhz the coupler generates roughly 4 times more voltage that let’s say in 7Mhz. So a system that compares direct and reflected signal and triggers when the latter is percentually too high was needed, therefore an operational a...