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Category Archives: Schematics

Schematics or Circuit Diagrams that aid learning.

Make a Shake LED Flashlight

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I  was enlightened about this Battery Less wonder. This is a boon for rural areas and an emergency tool which depend only on your will and your tendons. I found this bright flash of information when i was looking for supercap vendors.

Learn about Supercaps, dynamo and White LED

Richard J. Nelson on the LED Forever Flashlight. – The future of low power lighting is in the use of the Light Emitting Diode, LED. Sooner or later you will buy one or more LED lights or lamps. The two primary advantages of an LED light source is it’s efficient light generation (exceeding that of fluorescent lamps) and long life, typically 100,000 hours. That is 50 to 100 times more life than most of the bulbs in your house.

Learn about the Eternal Torchlight

This is a Linear Dynamo LED Torch which uses a SuperCapacitor to store the energy. Easy to repair and maintain if necessary.

It uses no batteries and requires only the single LED included. You can even leave the flashlight unused in your car’s glove box for years and you’ll always get that all-important light when you need it most. Forever Flashlight lll pays for itself quickly by saving you the cost of batteries and bulbs.

Hobby Circuits – Bill Bowden

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Bill Bowden’s Circuits is one of the oldest Web Reference, it was hosted by CompuServe homepages and later moved to his own domain website.

A small collection of electronic circuits for the hobbyist or student. Site includes over 100 circuit diagrams, links to related sites, commercial kits and projects, newsgroups and educational areas.

Hobby Circuits - Bill Bowden

Most of the circuits can be built with common components available from Radio Shack or salvaged from scrap electronic equipment…….

Hobby Circuits – Bill Bowden

Some of the Highlights in this website

  • 32.768 KHz Oscillator Using A Common Watch Crystal
  • 40 LED Bicycle Light (555 Timer – 6 volt)
  • Descrete LED fading circuit using 5 transistors
  • Mechanical Wall Clock Quartz Synchronizer
  • Neodymium Magnet Single Pole Motor
  • Variable Voltage and Current Power Supply
  • Micro Power AM Broadcast Transmitter

The Radio Electronics Magazine

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Radio-Electronics was an American electronics magazine that was published under various titles from 1929 to 2003.You can Read them all here .

Radio Electronics Magazine at The Internet Archive

Recently i found a collection of those mags at Archive.org …..

Radio Electronics Magazine at Archive.org

Hugo Gernsback, sometimes called The Father of Science Fiction, started it as Radio-Craft in July 1929. The title was changed to Radio-Electronics in October 1948 and again to Electronics Now in July 1992. In January 2000 it was merged with Gernsback’s Popular Electronics to become Poptronics.

Gernsback Publications ceased operations in December 2002 and the January 2003 issue was the last.

Over the years, Radio-Electronics featured audio, radio, television and computer technology. The most notable articles were the TV Typewriter (September 1973)[1] and the Mark-8 computer (July 1974). These two issues are considered milestones in the home computer revolution.

Radio Electronics Magazine at SWTPC

Radio-Electronics was aimed at electronics’ professionals such as radio and TV repairmen. And they were men, the tag line on the cover was “For Men with Ideas in Electronics”.

Radio-Electronics & Electronics Now

Radio Electronics was the “new” name for Radio Craft magazine.. Hugo Gernsback, sometimes called The Father of Science Fiction, started it as Radio-Craft in July 1929. The title was changed to Radio-Electronics in October 1948. In July of 1992 transitioned to “Electronics Now

Circuit Exchange International

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There are ten categories of schematics, a unified circuit analysis, design and theory page, and also a practical electronic section. The simulation section features the “TINA” and “Circuit Maker” programs. (this is a first generation website )

Circuit Exchange International

Some interesting sections are Alarms & Security Circuits, Control & Interfacing, Radio Circuits, Power Supplies & Circuits, Timing Circuits.

Circuit Exchange International

 

First created back in March 1999 and intended for electronics hobbyists, engineers and enthusiasts everywhere. Currently there are 310 schematics divided into 11 categories. Also included are tutorials, design and simulation sections.  – Andy Collinson

G-switch timer – Vern Knowles

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The timer is built using four small inexpensive CMOS integrated circuits. This allows it to run on just 3V from two small AAA batteries. U1 is a 74HC688 8-bit equality comparator. It compares the switch settings to the counter output and will set pin U1-19 low when they match. The actual counter is U2. It is a 74HC4060 14-stage binary ripple counter with built-in oscillator.

The G-switch itself uses a cantilevered metal bar that pivots down as the rocket accelerates upward. The metal bar actuates a small micro-switch that triggers a digital counter to begin the timing sequence. The timer is designed so that it will not start unless the micro-switch has been activated for a duration of at least 0.5 seconds.

G-switch timer - Vern Knowles

G-switch timer – Vern Knowles – The timer was built using a small prototyping circuit board and point-to-point wiring.

U3 is a 74HC74 D-type flip-flop that is used as part of the triggering logic. U3-12 will be low when the counter matches the switch settings. Consequently, on the next oscillator clock edge from U2-9 the flip-flop output at U3-9 will go low. This is the event that activates the 2N4403 transistor that fires the flash bulb.

Flashing Mains Neon Lamp

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Here is a Neon Flasher circuit (untested) for a user request at Circuits FAQ. This can be built into a switchboard or a gadget for indicating Live Power.

D1-C1 form a simple half-wave rectifier, The Cap charges to peak voltage and can store charge for a long time if there is no bleeder. So while building it take extra care. This forms a DC supply across C1. C1 is a Plastic High-voltage cap, IN4007 has a 1KV rating, so it is ok for 230V rectifier.

R1 Charges C2 and when C2 reaches 60-80V depending on Neon, the neon breaksdown. C2 Discharges, Neon Recovers, The C2 starts charging again and so on and on. It Oscillates, probably in a Ramp Waveform. But do not use your Scope on this, you will regret it a lot. This is a live circuit and needs a special probe.

“Oh, i will put the probe it in 10M mode” will not do. The ground clip of the probe goes to Electrical Earth which is ‘connected’ to Neutral in the mains wiring. So you put the earth crocodile clip on the live point. There will be flashes and fireworks. So you need to isolate both terminals of scope. Please use your costly equipment with great care.

For the 1 Meg use two 470K in Series for 230V AC, that is safer. The circuit is live, so take precautions. The 0.47 Micro Farad can be increased if you want a slow flash. If the Mains 50/60 Hz Flicker is too much, the 1 uF can be made 2 uF, or use 4 – 1N4007 as a bridge rectifier.

From Schematics of delabs

User Feedback –

R1 of 4.7M and C2 of 0.47uF Works well at 230V AC. Try your own Combination. Less than 1M may damage Neon.

VU Meter Circuits and Projects

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Here is a collection of web pages of VU Meter projects that helps a newbie getting into the Electronics DIY Hobby Land.

VU Meter Circuits and Projects

A Hobby now in your School days or College can help you build a strong profession later. It is Edutainment that will make productive use of your spare time. Friends can do it as a group, during holidays. Parents should encourage healthy hobbies, as the children will grow in a positive and creative atmosphere.

Stereo led level meter – This is it. It’s a STEREO LED LEVEL METER. It’s the cheapest and best bar graph display available and best of all, it uses readily available components.

VU-meter by Archy – Then it hit me. A VU meter, big, beautiful, professional! From that moment started my thoughts flowing. Those VU-meter ICs that are sold in every electronics shop?

LM3914 dot-bar display driver – The LM3914 is a monolithic integrated circuit that senses analog voltage levels and drives 10 LEDs, providing a linear analog display.

Knight Rider Display Project – This project started out as a VU meter. I reused parts and pieces to improve the VU meter and give it additional functionality. It is amazing how much time it takes to create a small thing like this.