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Expanded Scale 12v Battery Voltage Monitor - The circuit below expands the battery voltage monitoring scale for a 12v battery so a more accurate voltage reading can be made. The numbers printed onto the face of a standard 0v to 5v meter are changed so the scale ranges from 10v to 15v. http://archil . . . Circuit by David Johnson P.E.-October 16, 2005
Flat Battery Indicator - This small circuit was developed to monitor the battery in a model hovercraft. The lift in the model is produced by an electric motor driving a fan. To avoid the possibility of discharging the rechargeable battery pack too deeply, the design lights a conspicuous LED mounted on the model when a preset threshold voltage is__
Frequency Meter & Pulse Generator - Simplicity in circuitry was the design direction. Zero mass (firmware only with no physical components) would the ultimate achievement. This instrument doesn't have any front panel controls because the user interacts via an RS-232 terminal program at 9600 baud. I needed a frequency meter for my experiments in Nondu, Thailand, where I really don't have room for a lot of instruments. I wrote some straight forward code to read the 16 bit counter in the AT90S2313 after period of time, which was determined by running a timing loop. By the way, I tried various approaches using interrupts from the 8 bit timer to set the counting interval, but found timing uncertainty resulted in intolerable jitter in the measurements, to as inelegant as it is, timing loops turned out the be give the best results. The results of the counts are converted to acsiI and sent to the terminal. After finishing the frequency meter, I realized that only half the Flash ROM was used and that I could fit a handy pulse generator program I found on the web into the same chip, but having two instruments in one. The result is a combined counter and frequency meter. The chip flips between the two programs, The only things common between the two programs is some initialization and some of the serial port i/O code. The pulse generator firmware is pretty much as originally published, except that I modified it to drive a resistor network so as to allow the pulse output amplitude to be selectable. __ Designed by Dick Cappels
GMR Sensors Manage Batteries - 09/02/99 EDN Design Ideas: The past few decades have seen remarkable progress in magnetic-sensor technology. Early and current sensors exploit the Hall effect; more recent devices use an effect called giant magnetoresistance (GMR]. GMR sensors use semiconductor processing of materi Design by D Ramirez and J Pelegri, University of Valencia, Spain - September 2, 1999
Ground Resistance Tester - UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0.1ohms. This resistance must be tested with actual line current in excess or 10 amps. The circuit shown uses a couple of LEDs to indicat . . . Hobby Circuit designed by Dave Johnson P.E.-April 28, 2001
HF AC Millivoltmeter adapter - intended for use past 200 kHz, this adapter changes HF AC voltages between 2 mv P-P and 200 mv P-P to the corresponding DC level with linearity of better than 1 millivolt. A on-board calibration signal aids in calibration prior to use. __ Designed by Dick Cappels
HF/VHF/UHF Test Oscillator - This test oscillator covers 16 MHz to 300 MHz in six bands, using varactor tuning. It has a high level output to drive a frequency meter and two sine wave outputs, one of which is 50 Ohms.
This article was published in Croatian in infoelektronika magazine in June, 2012 (cooperatively) __ Designed by Dick Cappels
High Capacity Alternative to 9 Volt Battery - Get ten times the capacity of a 9 Volt battery to power your devices. __ Designed by REUK-Renewable Energy UK website
Improved Vibrating Battery Tester - Many blind and deaf-blind people use portable electronic devices to assist their everyday lives but it is difficult for them to test the batteries used in that equipment. Talking voltmeters are available for the blind but there is no commercially available equivalent usable by deaf-blind persons. This device enables blind, deaf-blind and sighted people to__
Indicates a Low battery - 02/03/14 - EDN Design Ideas: it may seem a bit counterintuitive to power on an LED when a battery is already low, but this Design idea does it with aplomb Design by James Wood
Inductance meter for RF Inductors - needed a way to measure hand-wound RF inductors in my second lab, and since I would only be doing this occasionally, I didn't need anything fancy, and since once a friend finishes his AT90S1200-based design, I plan to make one myself, I figured I'duse this for less than a year, so I didn't want to invest __ Designed by Dick Cappels
In-Situ Battery Test Probe - This item describes a simple probe that allows in-situ AA and AAA battery voltage and current drain measurements without removing the cells from the holder. In use, the probe is simply pushed between the positive end of one cell and either the negative end of the adjacent cell or the battery holder terminal. The probe […]__
LC Determination by Resonant Frequency Measurement ATtiny2313, AT90S2313 - A well known L/C measurement circuit is pressed into service to make a bare bones measurement circuit. __ Designed by Dick Cappels
Lead-Acid Battery Low Voltage Indicator - Lead-acid batteries should not be discharged below a certain voltage. Discharging a cell below about 1. 8v and can often damage it, which will result in a lower amp-hour capacity. Large battery banks are critical in off-grid energy storage systems. One . . . Circuit by David A. Johnson P.E.-July 30, 2006
Lead-Acid Battery Monitor - This mini-project came about from building a garden shed. I decided to re-purpose an old UPS battery along with some spare halogen downlighters for illumination. But as I researched lead-acid technology, I decided that I needed something rather more sophisticated than a simple switch if I wanted the batteries to survive __ Designed by Mark Hennessy
LED 12 Volt Lead Acid Battery Meter - in the circuit above, a quad voltage comparator (LM339) is used as a simple bar graph meter to indicate the charge condition of a 12 volt, lead acid battery. A 5 volt reference voltage is connected__
LED Battery Condition Indicator - in the circuit below, a quad voltage comparator (LM339) is used as a simple bar graph meter to indicate the charge condition of a 12 volt, lead acid battery. A 5 volt reference voltage is connected to each of the (+) inputs of the four comparators and the (-) inputs are connected to successive points along a voltage divider. The LEDs __ Designed by Bill Bowden
LED Flasher Indicates Low Battery Condition - 01/02/97 EDN Design Ideas: Many portable electronic devices could benefit from a visual indication when their battery requires replacement. Typical low-battery indicators simply turn on an LED when the battery voltage drops below a certain value. Such circuits actually accelerate the battery's extinction by drawing excessive current. The circuit in Figure 1 draws a mere 1 m A in its standby mode and averages only 20 m A when activated. The low current imposes a minimal burden on any battery circuit. An off-the-shelf, undervoltage sensor IC (IC 1) monitors the battery voltage-- Design by David Johnson, DiscoverCircuits.com
Lithium Battery Tester - I bought some lithium ion rechargeable batteries a while back. I was planning on using them to modify some solar powered LED spot lights. What I like about these new batteries is that they are the same size as a standard 1.5v alkaline AA cell . . . Hobby Circuit designed by David A. Johnson P.E.-February 05, 2012
Little More Serious Frequency Meter/CounterATtiny2313, AT90S2313 - Maximum input frequency is specified to be 30 MHz in the multi-chip configuration, and in single-chip configuration, there are both 5 MHz and 10 Mhz versions operating with 10 and 20 MHz crystals, respectively. All versions have 9 1/2 digit resolution. I have used __ Designed by Dick Cappels
LM3914 Battery Monitor - This circuit should be powered by its own battery, otherwise you might get an innacurate reading. hook the to-be-monitored battery to pin 5 of the chip. __ Designed by Andy Wilson
Low battery cut-off for a car or truck - Also acts as a Master On / Off Switch. NOW, Also a New P-Mos Version. Supplies Positive voltage to grounded devices. __ Designed by G.L. Chemelec
Low Battery Indicator - File contains several designs, please scroll to find this circuit. Here is a low battery indicator that flashes a lamp when the battery voltage falls below about 5 volts. The circuit draws about 25 microamps when not flashing so battery life is not significantly shortened by the circuit. The two 1 megohm resistors set the switching point at V/2 (plus a little due to the emitter-base diode drop) and when this voltage is above the zener voltage the circuit cannot turn on. When the battery voltage drops below 5 volts, the base voltage drops to 2.5 volts and the emitter can reach a voltage sufficient to turn on the PNP (2N4403 or similar). When the PNP conducts, the NPN also conducts dropping the voltage across the circuit even more and the circuit snaps on. When the 4.7 uF capacitor has discharged, the circuit turns off and the capacitor begins charging again. __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Low Battery Indicator Ii - This circuit indicates the remaining battery life bAy varying the duty cycle and flash rate of an LED as the battery voltage decreases. In fact, the circuit actually indicates five battery conditions: (1) a steady glow assures indicates that the battery is healthy; (2) a 2Hz flicker (briefly off) indicates that the battery is starting__
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 David Johnson P.E.-December 24, 1998
Low Voltage Battery Disconnects - Find out more about low voltage battery disconnect (LVD) circuits - used to protect batteries. __ Designed by REUK-Renewable Energy UK website
Low Voltage Indicator for Lead-Acid Battery - Lead-acid batteries should not be discharged below a certain voltage. Discharging a cell below about 1. 8v and can often damage it, which will result in a lower amp-hour capacity. Large battery banks are critical in off-grid energy storage systems. One . . . Hobby Circuit designed by David A. Johnson P.E.-July 30, 2006
Low-Battery Detector Preregulates Input Voltage - 08/15/96 EDN Design Ideas: The circuit in Figure 1 uses the comparator and voltage reference of a low-battery detector to preregulate the input voltage. The circuit provide as an additional regulated voltage output at VOUT1 and significantly reduces the linear regulator's (VOUT2's) power dissipation. The two outputs (12V at 50 mA and 5V at 100 mA) are independent. Design by Khy Vijeh, Analog Devices Inc, Santa Clara, CA
Low-Battery Indicator has High-Efficiency - 05/03/01 EDN Design Ideas: The usual method for implementing the low-battery warning featured in most battery-operated equipment is to illuminate an LED. However, the LED exacerbates the low-battery condition. You can greatly reduce the LEDs power consumption by operating it at a low frequency and a low duty cycle. Design by Joe Neubauer
Low-Battery Indicator Uses Fleapower - 4-Sep-03 EDN Design Ideas: it is always desirable to use a low-battery indicator that consumes as little power as possible. For a 9V, 450-mAhr alkaline battery, a 50-µA low-battery indicator can by itself run the battery down in a littlethan a year. Battery-powered devices that need to run continuously for a long time require battery indicators that consume minimal power Design by Yongping Xia, Navcom Technology, Redondo Beach, CA
Low-battery voltage cutoff consumes just 1 mA - 09/11/98 EDN Design Ideas: NOTE: FILE has several circuits, please scroll to find this one. A low-battery voltage-cutoff circuit prevents overdischarge of a rechargeable battery. An obvious requirement of this circuit is extremely low power consumption. Figure 1a's simple circuit has a measured current consumption of approximately 1. 2 mA and uses only two Design by Yongping Xia, Teldata Inc, Los Angeles, CA
Low-cost active load draws constant battery power - 04/13/00 EDN Design Ideas: Unlike nickel-metal-hydride and lithium-ion rechargeable batteries, the discharge voltage of alkaline batteries is not constant and tends to vary from 1.5 to 0.8V per cell. Alkaline-battery manufacturers specify the discharge life of their batteries under constant powerloads. Because of the varying discharge voltage, you can't simply connect a load resistor to the cells to verify or measure power profiles without incurring a lot of error in your measurements. The circuit in Figure 1draws a constant power from the battery pack. Thus, as the battery voltage decreases, the load current increases. A single potentiometer allows a user to set the desired wattage draw. The circuit is simple and inexpensive to build. Design by Doug Farra
LT1304: Micropower DC/DC Converter with Independent Low-Battery Detector - DN120 Design Notes__ Linear Technology/Analog Devices |
