AC to DC Power Supplies

MINIATURE ISOLATED AC/DC POWER SUPPLY This circuit uses a novel approach to produce a fully isolated and regulated 5 volts @30ma from the 120vac power line. It uses two tiny SCRs that alternately discharge two capacitors through a miniature high frequency transformer. The voltage spikes produced through the transformer are rectified, filtered and regulated. A very common 8 ohm audio impedance matching transformer can be used for the transformer. Published in EDN, Feb. 17, 1992

CAPS PROVIDE VOLTAGE BOOST TO SERIES REGULATOR This circuit adds some capacitors and diodes to a traditional transformer type series regulator circuit to extend the normal operating range. It can insure regulation during low line voltage conditions or it can squeeze a few more watts out of a plug-in-the-wall power adapter power supply.

LOW POWER 12,000 VOLT POWER SUPPLY If you need about 12,000 volts DC for an ion generator this circuit might be the ticket. It draws power from the 120vac power line but it uses a small 6KV camera flash trigger coil. The output signal is isolated from the power line. Although the circuit can only deliver about 5uA of current it can produce dangerous shocks, so be careful.

240VAC TO 5VDC POWER SUPPLY This is simple way to power some 5v logic from a 240vac source. If a 120vac power adapter is used, the circuit will also work for 120vac power lines.

12 Volt to 9 Volt DC Converter: Car Converter for12 Volt to 9V

2 Watt Switching Power Supply: from 6V to14V

5 Volt DC From RS232 Signals: The circuit of Figure1 produces a semi-regulated5-Volt output from an RS-232 port. Unlike a PC-mouse supply or comparable that rely on the modem-control signals DTR and RTS, this one operates with a3-wire port GND, Rx, and TX, and obtains power only from the TX line. The output current-about 8mA-is sufficient for CMOS microcontrollers and other low-power .

6 to 12 Volt Converter: This circuit can provide up to 800mA of12V power from a 6V supply. The circuit is simple, about 75% efficient and quite useful.

Circuit offers improved active rectification: EDN-Design Ideas / Rectifiers convert ac signals to dc. You can combine a diode and a load resistor to create a half-wave rectifier, provided that the amplitude of the ac source is much larger than the forward drop of the diode (typically 0.6V). Unfortunately, you can't use this method to rectify signals that are smaller than a diode drop...

DC to DC Converter: will produce a 85-Volt voltage from +3V, usable for low power applications

Fast Rectifier Circumvents Input Level Effects: 12/22/94 EDN-Design Ideas

Full Wave Rectifier uses Current Feedback Amps: 03/27/97 EDN-Design Ideas

Full Wave Rectifier uses Current Feedback Amps: 07/20/95 EDN-Design Ideas

High Speed Rectifier uses No Diodes: 03/30/95 EDN-Design Ideas

Method provides self timing for synchronous rectifiers: 05/16/2002 EDN - Design Ideas / Synchronous rectifiers are MOSFETs, driven in such a way as to perform a rectifying function. They often take the place of diodes in the output-rectification stage of switching power converters, because of their lower on-state power loss. In power circuits, synchronous rectifiers are often complicated to use because of timing issues..

One 9 Volt Battery gives +18, +25, +33V: This circuit is based on MAX1044 is a charge pump converter.

OpAmp Rectifier Signals Input State: 07/21/94 EDN-Design Ideas

Output Adjustable Flyback Converter:

Precision AC / DC Converters: National Semiconductor Application Notes,28-Jun-1996

Precision Rectifier is Glitch Free to 1 MHz: 05/12/94 EDN-Design Ideas

Precision Rectifier Reduces Ripples: 03/03/97 EDN-Design Ideas

Step Down Rectifier Makes a Simple DC Power Supply: EDN-Design Ideas - A simple and useful nonisolated rectifier features voltage step-down operation, acceptable Class A line-current harmonics, inherent short-circuit protection, and, optionally, a regulated output

Transformerless Mains Power Supply: This power supply does not really excel in power efficiency, but it is the cheapest and most compact solution for a small power supply. Note that the low voltage output is directly connected to the mains; it cannot be used when the low voltage part can be touched. With the component values of the schematic, the circuit can supply12V /15mA max.

Transformerless Power Supply:

True RMS Detector: National Semiconductor Application Notes,28-Jun-1996

Two OpAmps Make Fast Full Wave Rectifier: 03/14/96 EDN-Design Ideas

Two Watt Switching Power Supply: from 6V to14V

Unregulated Power Supply: