Power circuit diagrams

Variable Voltage Regulator

Variable Voltage Regulator

Gyrator Circuit

An electronic recitification circuit. The use of large, heavy and expensive electrolytic capacitors is avoided, being replaced by an active transistor in this gyrator circuit.

Power Outage Warning

5 to 15V supply - LED indicator. Adjustable time detection

Broken Charger-connection Alert

Detects if a device is not properly connected to its supply Suitable for battery chargers, portable appliance supplies etc.

Small Variable power Supply

Features: 1.3-12.2 V, 1 A, over-current protection. This is a simple but reliable device based one of the oldest integrated voltage regulators of them all - the LM723.

Basic UPS

This circuit is a simple form of the commercial UPS, the circuit provides a constant regulated 5 Volt output and an unregulated 12 Volt supply. In the event of electrical supply line failure the battery takes over, with no spikes on the regulated supply.

12 Volt 20 Amp Power Supply

A 12 Volt high current 20 Amp power supply. The output voltage is variable from 12.2 Volt to 14.4V so can be set for any device requiring voltage and current in that range. This PSU uses an LM723 as the regulator, 4 parallel connected outboard pass transistors and has current limiting above 25 amps.

Nicad Battery Charger

A basic nicad battery charger using a single medium power transistor.

Under Voltage Circuit

This under voltage circuit may be used as an add-on to an existing power supply or standalone. The circuit draws power from an existing power supply, which may be up to 36 Vdc. Once voltage drops below a preset level the output swings high. A CA3140 MOSFET op-amp is used as a comparator, the output can drive loads of up to 10mA so can drive a low current LED directly. Additional buffering is required for higher loads.

Regulated DC power supply

This is a Regulated DC power supply with short circuit protection and with current limiter.