2 Transistor Oscillators - This page has two unusual two-transistor oscillators. I set the component values for a low frequency application. Both circuits draw only about 1 micro amp of current. . . Circuit by David A. Johnson P.E.-December, 2002 3 Volt Low Battery Voltage Flasher - This circuit is designed to monitor two alkaline cells (3v) that form the battery often used in portable electronic equipment. . . Circuit by Dave Johnson P.E.-January, 1998
3.3V to 5.5V input (500mA max) charging 4.4mF super cap (3.3V at 800mA) & providing 1.8V at 400mA - The LTC3619 is a Dual 400mA/800mA monolithic synchronous buck regulator with an input supply voltage range is 2.5V to 5.5V, making it ideal for Li-Ion and USB powered applications __ Linear Technology/Analog Devices App Note, Mar 23, 2010
3.3V/10mA Regulator from a 4mA to 20mA Loop - This circuit is a 3.3 V/10mA regulator that extracts its power from a 4mA to 20mA loop. This circuit demonstrates how an LTC1474/LTC1475-based regulator is easily optimized for such low current applications. The 2W sense resistor limits the peak inductor current to 40mA to minimize current ripple and provide good efficiency __ Linear Technology/Analog Devices App Note, Mar 16th 2011
32Khz Ultra Low Power Crystal Oscillator - I have used this circuit many times when I needed a low frequency reference, which did not draw much power. With the components show, the current from a 3v battery is less than 1.2 microamps. . . Circuit by David A. Johnson P.E.-December, 2004
3MHz Micropower Synchronous Boost Converters Deliver 3W from Two Cells in a Tiny MSOP Package - DN246 Design Notes __ Linear Technology/Analog Devices
3V & 5V 12-Bit Rail-To-Rail Micropower DACs Combine Flexibility & Performance DN127 Design Notes__ Linear Technology/Analog Devices
3v 2hz Oscillator - This is yet another method to generate low frequency output pulses. The circuit uses an inexpensive under-voltage monitor IC and a couple of cheap MOSFETs. It could easily be modified to produce pulse frequencies from about one cycle per minute to a maxim. . . Circuit by David Johnson P.E.-June, 2000
3v Powered Loud Beeper - Getting a high sound intensity from a piezoelectric type beeper is not easy when the available DC supply is only 3v. The circuit below is not only efficient but produces a very intense sound. The circuit combines a voltage boost section with a resonant. . . Circuit by David Johnson P.E.-February, 2009
40Khz Burst Laser Diode Driver - Some laser tag or simulated combat games can use this circuit to send short bursts of modulated laser light at the opponent's vest, equipped with a matching light receiver. The circuit operates from three 1.5v cells (4.5v) that should provide enough energy . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
40Khz Light Detector with High Ambient Light Immunity - This circuit is designed for detecting infrared light modulated at around 40KHz. It’s feedback scheme cancels much of the DC component from ambient light. It’s conversion factor is about 100 millivolts per microwatt of 900nm light.. . . Circuit by Dave Johnson P.E.-July, 2006
40KHz Light Detector with Sunlight Immunity - This hobby circuit below was designed to turn on an external 12v relay, whenever it detects light from a nearby LED light source, modulated at 40KHz to 50KHz. This circuit was originally designed to operate from a fast moving vehicle . . . Hobby Circuit designed by David Johnson P.E.-July, 2006
50ua Current Drives Solid State Relay Requires Only - Most solid state relays require at least 5ma and often more input control current, to fully turn on the device. But such current levels often force battery powered circuits to use excessively large batteries. The relay hobby circuit shown below demands only 50uA of input current . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000
555 Timer Drives Multiple LEDs from One NiMH
Cell - 2-Oct-08 EDN-Design Ideas Using a CMOS
555 timer, you can drive seven high-brightness LEDs from a single 1.25V cell Design by Chuck Irwin, Hendersonville, NC
80V Linear Regulator is Micropower - DN314 Design Notes __ Linear Technology/Analog Devices
9v Battery Eliminator - If you use 9v battery powered devices for long periods of time, you may get tired of constantly changing batteries. The circuit below can be wired into any 9v battery powered device, drawing power from an external AC to DC power adapter. I designed the circuit. . . Circuit by Dave Johnson P.E.-December, 2009
9v Battery Voltage Monitor - This circuit turns on a LED whenever the voltage of a standard 9v battery connected to the circuit drops below 7.2 volts. It uses a LTC1440 comparator, which also contains a 1.18v reference diode. In standby mode, the circuit draws only 4uA. . . Circuit by David A. Johnson P.E.-July, 2006
9V Pulse Generator - It is hard to design a pulse generator that produces clean logic pulses while drawing very low current. This circuit is designed to produce short 2mS pulses at a rate of one per second while drawing only 1 microamp from a 9 volt battery. . . Circuit by Dave Johnson P.E.-June, 2000
A Low Power RF ID Transponder - This is the Grand Prize winner in the design category of the 1993 RF Design Awards Contest. This entry exhibited both innovative use of RF technology and an elegant implementation of that technology __ Designed by Raymond Page
Advertising Badge #1 with Flashing LED - I have seen numerous flashing light badges at trade shows and conventions. They are often handed out as gifts to promote some business. The devices often use inefficient circuits, which cause the battery power source to be quickly depleted. . . Circuit by Dave Johnson P.E.-March, 2002
Advertising Badge #2 with Flashing LED - This circuit uses a CD4013 dual D Flip/Flop IC. A single lithium battery will provide months of continuous LED flashing. It also has a tiny push-button switch to turn on and off the light flashing. . . Circuit by David Johnson P.E.-March, 2002
Alarm Sounds At Freezing Temperatures - This electronic hobby circuit below is designed to activate a beeper alarm, whenever the outside air temperature is below 0 degrees C (32F) . A 9v battery powers the hobby circuit. The average 9ua current is so low that the battery should last for many years . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006
Alarm-Piezo Device Detects Motion - Using a piezo device, this circuit will activate a beeper whenever the circuit is moved. It could be used as an earthquake alarm. . . Circuit by Dave Johnson P.E.-July, 2006
AN23Micropower Circuits for Signal Conditioning - Linear Technology AN23 __ Designed by Jim WilliamsApr 1st, 1987
Applications for a New Micropower Low Charge Injection Analog Switch - DN38 Design Notes__ Linear Technology/Analog Devices
Applications of the LT1300 & LT1301 Micropower DC/DC Converters - AN59 Linear Technology This note covers operation and applications ofLT1300 and LT1301 high efficiency micropower step-up DC/DC converter ICs. Internal operation ofICs is described in detail. A variety of applications are presented, ranging from straightforward 2-cell to 5V converters and 5V to 12V converters to exotic transducerbased circuits such as flame detectors__ Linear Technology/Analog Devices
Audio Activated Switch - This circuit will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal. It could be used to turn on a relay, routing the signal to were it is needed.. . . Circuit by David A. Johnson P.E.-July, 2006
Audio Amplifier using BC109C - As can be seen from the circuit diagram we are really using five transistors as the BD679 and BD680 are "Darlington" pairs of transistors. The led must be a green led for correct operation. (The voltage across a green led is higher than the voltage across a red led.) When using a 12v supply the voltage at T1 collector should be (about) 5v and at T2 base (about) 7v. This amplifier will be unstable (it will oscillate) without the 4k7 variable resistor connected to the input. __ Designed by © David Hoult |