# Dynamo Current and Voltage Regulator by TL084

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Let’s start analyzing the circuit in idle condition, when the engine is stopped. The battery voltage at B+ cannot pass to D+, because D1 blocks it. D+ is at ground level, because of the low resistance of the dynamo between D+ and D-. Q1 is biased off, which leaves the… Read more »

# Solar panel voltage regulator by LM358 , TIP142

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Here is the schematic diagram of my regulator. You may want to print it out, and then go on reading. This regulator is designed for 12V systems employing panels of up to 7A total current, and loads of not over 20A. It can be easily modified for greater currents. U1A… Read more »

# Mini Zener-based solar engine by 2N3904

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The capacitor charges until the PNP transistor (here shown as a 2N3906, but you could also use a BC327) receives base current through the Zener and turns on. Then the NPN transistor (here shown as a 2N3904, but you could also use a BC337) turns on and the capacitor is… Read more »

# Uninterruptible Alarm Power Supply by 7805

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Although this Power Supply was designed for the Modular Burglar Alarm – it has other applications. It provides an output of 12-volts – at a current of up to 1-amp. In the event of a mains failure – the back-up battery takes over immediately. And when mains power is restored… Read more »

# Current Limiting Bench Power Supply for L200

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This is a 1-amp variable-voltage PSU. It adjusts from about 3v to 24v: and has the added feature that you can limit the maximum output current. This is invaluable when (for example) you power-up a project for the first time or soak-test a piece of equipment. SW3 is the on/off… Read more »

# Over Voltage Protection

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Safety devices like fuses provide protection against excess current, but do nothing for transients and short duration spikes of high voltahe on the power supply lines.This circuit uses the “crowbar” method and provides fast protection against transient voltage spikes, transients that could cause damage to sensitive components. The thyristor will… Read more »

# Soft Start for power supply units

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The circuit will limit the current through the supply wires to 5.5A for about 1.5sec. After that time the relay will close and the current flow won’t be restricted anymore. This is a very interesting circuit if you have a large toroid with big electrolytic caps connected to the power… Read more »

# Delay to supply voltage for surge protector by scr

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Power source that, when connected to an external circuit, and now will turn to a current surge.Power supply is a high voltage surges.External circuit therefore damage.Which can solve this problem with the delay to a power source.When supply switches.Delay circuit to work, the delay occurred during the current surge.Then connected… Read more »

# Over voltage and low voltage protection circuit

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This is an electrical circuit protection device sound disappeared, when too much voltage 220V, and protection, when pressure is too low with Using the relay cut off power when voltage problems. From the circuit when the voltage is 220 volts AC through a transformer T1. It serves to reduce the… Read more »

# Battery Saver by Pushbutton Version

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The Battery Saver is designed to prolong the battery life in small toys and devices by disconnecting the load after a preset period. The two versions shown switch up to one amp and give about one minute of operation before shutting off. When the switch is pressed, the capacitor charges… Read more »