Category «Power Supply»

Selectable Voltages 6V, 9V, and 12V Linear Voltage Regulator

  We can build a multiple voltage power supply 6, 9, and 12V  (AC-DC Adapter) with the circuit shown in the following schematic diagram.  Not only provide multiple voltage output with single voltage supply, this circuit add the benefit of regulating the voltage for better stability. The TIP31 transistor should be installed with proper heat-sink …

Power Saver for Relays

Relays are normally operated at current level where it can initiate the mechanical metal contactors movement. After contacts has been established, the current level needed to keep the conductor plates stay attached is actually smaller than the current to initiate it. This power saver circuit seems to have opposite mechanism of surge protector. This circuit …

Black Light (UV Tube Lamp) Inverter

The voltage boosting in this circuit enable its operation to be powered by 2.5 V rechargeable battery (two cells 1.2V rechargeable batteries),  supplying 400 mA current at 26 V which is needed by the gas arc tube for portable ultraviolet lamp. This inverter circuit has a good efficiency as well, about 80%. Ultraviolet (UV)  light …

Variable Frequency Switch Mode Regulator

This voltage regulator circuit operates in switch mode. Using the configuration shown in the schematic diagram, this circuit has variable switching frequency, depends on the input voltage and load condition. The core controller of this switching regulator is a TL497 switching regulator controller IC. Here is the schematic diagram of the circuit: When the load …

Logic Power Control for 78xx Regulator

Logic power control of analog regulator can be useful in application where a digital circuit/controller need to control power source, such as in EEPROM programmer or other power controls.  This is a circuit provide ON-OFF control  for 78xx regulator using digital (TTL or CMOS) signal level. This circuit uses transistors in series with the 78XX …

Overvoltage Protector with Relay

An overvoltage protector circuit is shown in the schematic diagram below. This circuit will work to disconnect the protected device from the power supply when an overvoltage occurs at the supply. This circuit uses a silicon-controlled rectifier (SCR) and normally-closed 12-V relay, K1. The silicon-controlled rectifier is connected in parallel to 12-V line to monitor …