It is all too often necessary to augment the power supply of an existing electronic circuit because exactly the voltage that you need is missing. The circuit presented here may provide a solution in...
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Wednesday, 22 January 2014
Sunday, 19 January 2014
Touch-Select Audio Source
Often you need to connect output from more than one source (preamplifier) such as tape recorder/player and CD (compact disc) player to audio power amplifier. This needs disconnecting/connecting wires...
Motorcycle Battery Monitor
A circuit for monitoring the status of the battery and generator is undoubtedly a good idea for motorcyclists, as for other motorists. However, not every biker is willing to drill the necessary holes...
NiCd Battery Charger
The design of the charger is similar to that of many commercially available chargers. The charger consists of a mains adaptor, two resistors and a light-emitting diode (LED). In practical use, this kind...
Friday, 17 January 2014
LG G3 release date tipped for as early as May
Does it make sense for LG to launch the sequel to the LG G2 less than a full year after the flagship was announced? Probably not, but crazier things have happened in the mobile industry. Buzz out of...
Tuesday, 14 January 2014
Car Temperature Gauge
The Car Temperature Gauge is basically the same circuit as March's project with some minor changes to the input circuit. This circuit will display the water temperature to 1 degree resolutio...
Maximum Minimum Voltage Indicator
This circuit indicates which of three voltages in the range from about about -4V to about +4V - at A, B and C - is the highest by lighting one of three indicator LEDs. Alternatively, it can be wired...
Generation of 1-Sec Pulses Spaced 5-Sec Apart
This circuit using a dual-timer NE556 can produce 1Hz pulses spaced 5 seconds apart, either manually or automatically. IC NE556 comprises two independent NE555 timers in a single package. It is used...
Solar Relay
With extended periods of bright sunshine and warm weather, even relatively large storage batteries in solar-power systems can become rather warm. Consequently, a circuit is usually connected in parallel...
Video Amplifier
The video amplifier in the diagram is a well-known design. Simple, yet very useful, were it not for the ease with which the transistors can be damaged if the potentiometers (black level and signal amplitude)...
Smoke Alarm Battery Life Extender
While smoke alarms are quite cheap devices, the cost of 9V batteries quickly exceeds their purchase price. Added to that is the irritation of random beeps from the alarm as the battery reaches the end...
Simple Battery Isolator
This circuit is even simpler and employs a 6V feed from one of the stator connections on the vehicle’s alternator. This is connected to a 6V automotive relay (RLY1) which controls a Continuous Duty Solenoid...
Cash Box Guard
Most thefts happen after midnight when people enter the second phase of sleep called 'paradoxical sleep.' Here is a smart security circuit for your cash box that thwarts the theft attempt by activating...
Monday, 13 January 2014
HoneyDru USB Car Power Adapter
Having anything that is “cute” does seem to work these days, and considering how many of us carry a fair number of gadgets, it can be quite a task trying to make sure that all of them are fully juiced...
Disposable Batteries Recharger helps stretch every last dollar
We do know that times can get pretty hard for some of us out there, especially when you are out of a job for the longest time and your savings have just about run out. Well, that would mean being even...
Stepped Volume Control
Louder music, sirens or speech in response to higher ambient noise levels? This simple circuit has the answer, and it may enable your robot to be at least as noisy or loud-mouthed as the others in an...
SDR Soundcard Tester
The key to using a soundcard successfully in digital signal processing or digital radio applications lies principally in the characteristics of the soundcard itself. This applies in particular to SDR...
Test Beeper For Your Stereo
The test beeper generates a sinusoidal signal with a frequency of 1,000 Hz, a common test frequency for audio amplifiers. It consists of a classical Wien-Bridge oscillator (also known as a Wien-Robinson...
Low-Drop 5V Regulator
A 4-cell pack is a convenient, popular battery size. Alkaline manganese batteries are sold in retail stores in packs of four, which usually provide sufficient energy to keep battery replacement frequency...
Dual Opamp Buffered Power Supply
There will be instances where the currents from each supply will be unequal. Where this is the case, the resistor divider is not sufficient, and the +ve and -ve voltages will be unequal. By using a cheap...
Sunday, 12 January 2014
RS232 Voltage Regulator
There are many small applications where it would be preferable to power a device directly from an RS232 (V.24) interface, avoiding a mains power supply. Most ICs require 5 V, and the interface can provide...
Wall Mounted Bluetooth Speaker db60
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Want a high quality audio that lets you enjoy those amazing music at home? Take a look at db60, the wall mounted Bluetooth speaker should be a nice solution. The db60 is a premium quality, award-winning...
Hale Dreamer Alarm Clock Speaker Android Dock
Hale Dreamer Alarm Clock Speaker Android Dock tell you when it’s time to rise and shineto sleep is not always as easy as laying down and shutting your eyes. For many, there is a bit of science to it....
Negative-Output Switching Regulator
There are only a limited number of switching regulators designed to generate negative output voltages. In many cases, it’s thus necessary to use a switching regulator that was actually designed for a...
USB 5V to 12V DC-DC Step-Up Converter by LT1618
This is a 5V to 12V DC-DC step-up (boost) converter circuitry that is especially ideal for the USB powered applications. First of all a USB port has two current supply modes. Before detecting the connected...
Adjustable Symmetrical Power Supply Using LM317 and LM337
The circuit was designed to provide an adjustment with a power supply that is symmetrically designed while providing a voltage range of 1.25V to 30V at 1A current. LM317 – an adjustable 3-terminal positive...
Switch-Mode Power Supply
National Semiconductor has been producing and designing ICs for use in switch-mode power supplies for many years. The application of these devices is normally straightforward, helped by the excellent...
Transformerless Power Supply
This circuit will supply up to about 20ma at 12 volts. It uses capacitive reactance instead of resistance; and it doesn't generate very much heat.The circuit draws about 30ma AC. Always use a fuse and/or...
SSB Add-On For AM Receivers
Given favourable radio wave propagation, the shortwave and radio amateur band are chock-a-block with SSB (single-sideband) transmissions, which no matter what language they’re in, will fail to produce...
Friday, 10 January 2014
Rechargeable Snow Blower
You know what they say –the grass is greener on the other side of the fence. How any people do you know wish that they stay in an area where snow is in abundance? For folks who happen to live in such...
Input Impedance Booster II
The input resistance of a.c.-coupled op amp circuits depends almost entirely on the resistance with which the d.c. setting is determined. If CMOS op amps are used, the input resistance is normally high,...
Rugged PSU For Ham Radio Transceivers
This rugged power supply is based on the popular LM338 3-pin voltage regulator. The LM338 is capable of supplying 5 A over an output voltage range of 1.2 V to 32 V with all standard protections like...
Negative Auxiliary Voltage
Some circuits need a negative supply voltage that only has to supply a small current. Providing a separate transformer winding for this (possibly even with a rectifier and filter capacitor) would be...
General-Purpose NiCd Battery Charger
There is a wide variety of NiCd (nickel-cadmium) battery chargers on the market, but there are not many that can work from an in car 12 V cigar lighter. Such a charger would, for instance, be of interest...
Luminescent Moon Clock
Have you ever gone to the great outdoors, where there is no light pollution at all to spoil the view of the night sky, allowing you to check out plenty of stars along the way? Of course, during a full...
Friday, 3 January 2014
Remember Shelf
While we try our best, we can’t remember every small detail we’re supposed to keep track of. There’s gadgets to charge, groceries to buy, things to clean, appointments, meetings, and much, much more....
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