Free electronic circuit design and schematic diagram
Three separated LEDs is used on this battery monitor circuit. For red LED, it’s turn on from 6v to below 11v and turns off above 11v. For the orange LED, its illuminate between 11v and 13v and turns off above 13v. The green LED illuminates above 13v. This battery indication is suitable for monitoring your car battery condition. Green indicate […]
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This is Adjustable Constant Current Regulator circuit. This circuit can be used in a bench power supply to prevent the circuit that are tested from being damaged. This circuit can be adjusted to any value from a few milliamp to about 500mA. The max current is 500mA because it is the limit of the BC337 transistor in the current-limiting part […]
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When you insert peripherals, a problem can occur : The sudden load on the port’s 5V pin usually isn’t purely resistive. This load has a capacitive component that can cause a rapid and high-amplitude rise in current to levels well above the 500mA limit for USB port. When you connect a too-large hard disk to the port, a similar problem […]
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This is a RS232 Line Driver Power Supply circuit. This circuit can gives an output of ± 12V at ± 40 mA and only requires an input voltage as low as 4.2V. The efficiency of this circuit is better than 70%. This circuit provides a line regulation of ± 0.08% and a load regulation of ± 1.25% (from 10% to […]
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If you are traveling, you might need this device to charge your gadget along the way, since it is much cheaper to buy some standard AA batteries for backup than buying several rechargeable batteries of your gadget type. Below is a charger that more efficient than linear regulator like the “7805” while you are on the go. The most important […]
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This is 12V Car Battery Charger simple circuit. This circuit is designed to solve some problems that occurs in most car battery chargers. The problem that occur in most car battery chargers is when the charger is not turned off, the battery will overcharge, the plate of the charger will destroyed and the electrolyte of the charger will lost because […]
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This is 7.5V Uninterpretable Power Supply simple circuit. This circuit was used in many applications as a battery backup for low power requirements. This circuit contains a bridge rectifier, an electrolytic capacitor, and a transformer followed by a Zener controlled series pass transistor. This circuit can generate +7.5V stable output. Here is the circuit: The stand-by battery, 7.5V, is connected […]
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