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When testing a circuit, a source of voltage that is variable and has over voltage shutdown is veiy useful. In this circuit, Rl is adjusted to 1 to 2 V below the eventual shutdown threshold. R2 sets the trip voltage. When this voltage is reached, the circuit shuts the voltage to the circuit under test down. To reset, reduce Rl below trip threshold and depress reset switch SI. Over voltage Protection Circuit Diagram

The most simple polarity protection tehnique is to connect a series diode to the power line input. The diode conducts only when the power supply protection is correct. But the incovenient is that at higher current levels, the voltage drops and power loss of the diode affects the power level adversely. This polarity protection circuit is dimensioned for 12 V power supplies and avoids the voltage and power loss problem. By correct polarity, the current flowing to the D1 and the relay coil causes the relay contacts to activate. The NO contact closes powering the electronic device. The NC contact opens and the current supplying the relay coil is reduced to a low level just enough to maintain relay activation. source [link]

Project Description This is a very easy to build power supply that is based on LM338 5A adjustable voltage regulator. I am using the supply for a long time, have no problem yet. Only current adjust is missing but I overcome this situation by using an LCD panel ampermeter.  There is no PCB for the circuit. I took a 3x16 copper plate and strip the unused areas by a knife. If you want you can use analog meters instead of LCD panels.    Notes Use thick wires for connections.When connecting the LM338 to the heatsink use thermal paste. Use external supplies for LCD panels. They can be 9V batteries. The panels I use draws 1mA current and the batteries last sufficiently long time. If you have small transformers which can supply regulated 9V, you can use them. You need separate transformers for each panel!The transformer should be 100 Watt but if you don't need high current you can try transformers that you already have. (I can draw 6A from 100Watt transformer.)If you have...

This is the simple Reset Protection For Computers Circuit Diagram. This protection circuit is inserted between the reset switch and the motherboard. The earth connection of the computer must be linked to terminal of the protection circuit. The protection circuit can draw its power from the computer supply. When the circuit has been fitted, operation of the reset switch will not immediately restart the computer. Instead, a buzzer will sound to alert you to the reset operation.    Simple Reset Protection For Computers Circuit Diagram The buzzer is actuated for 4 s by monostable IC1A, which is triggered by the reset switch. During these 4 s, the output, pin 5, of IC1A ensures that the reset function, pin 10, of IC1B is disabled. When the reset switch is operated again, monostable IC IB will be triggered and this starts the reset procedure. Transistor T2 is then switched on for 0.5 s and the buzzer is deactuated via Rll and D4. The circuit around T1 and N4 ensures that IC1A can ac...

Hi everybody, Now I am here with a Automatic Battery Charger circuit having overcharge protection feature . In one of my previous post, we were discussed about a battery charger circuit. For that, the battery gets continously charged, and this overcharging affects the performance of the battery seriously. Today I am with a solution for that, as usual the circuit is simple to wire up, it consists only a few components and you can make this at your home itself. This circuit eliminates the battery draining due to overcharge, because the charger turnoff after the charging is made completed. Read More.....

Using the FPF270X adjustable over-current protection IC can be designed a very simple adjustable current-limiting electronic project .FPF270X provide full protection to systems and loads from excess current conditions.Minimum current limit is adjustable from 0.4A to 2.0A.The input voltage range is 2.8V to 36V. Loads can be activated or deactivated with a low-voltage logic compatible ON pin. Fault conditions can be monitored using the error flag pin and/or the power-good pin. All devices clamp the load current so that it cannot exceed an externally programmed current level. An over temperature feature provides further device protection in case of excessive levels of power dissipation. FPF2700 responds to an overload condition that lasts longer than a fixed blanking period by turning off the load, followed by a retry after the auto-restart time.The FPF270X has an adjustable 0.4A to 2.0A minimum current limit set through an external resistor, RSET, connected between ISET and GND.A 4.7 F t...

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...

This is a project of Protection For Your Electrical Appliances Circuit Diagram. Here is a very low-cost circuit to save your electrically operated appliances, such as tv, tape recorder, refrigerator, and other instruments during sudden tripping and resumption of mains supply. Appliances like refrigerators and air-conditioners are more prone to damage due to such conditions. The simple circuit given here switches off the mains supply to the load as soon as the power trips. The supply can be resumed only by manual intervention. Thus, the supply may be switched on only after it has stabilised.  Protection For Your Electrical Appliances Circuit Diagram Protection For Your Electrical Appliances The circuit comprises a step-down transformer followed by a full-wave rectifier and smoothing capacitor C1 which acts as a supply source for relay rl1. Initially, when the circuit is switched on, the power supply path to the step-down transformer X1 as well as the load is incomplete, as the rela...