Free electronic circuit design and schematic diagram
In automotive environment, it’s common that only single voltage power outlet is available. Using the very popular LM317 voltage regulator IC, we can build a general purpose DC adapter to adapt car’s power outlet voltage (12-14 Volts) to supply small DC devices requiring lower voltage level. On the following schematic diagram for the car power adapter, we can see that […]
Read more
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 to prevent overheating. A transformer […]
Read more
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 provide surge current to initiate […]
Read more
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 is also known as black […]
Read more
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 is low (draw only small […]
Read more
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 regulator, which it’s base is […]
Read more
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 for the overvoltage condition. This […]
Read more