Bowden's Hobby Circuits

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

Most of the circuits can be built using common components available from Radio Shack, Digikey, Jameco, Mouser, Allied electronics, or salvaged from scrap electronic equipment. Most circuits have been built, tested, and believed to perform as described, however possible mistakes may be found.

What's New Here? (09/15/16)

Digital/Computer 16 Bit PC Serial Port Receiver (CMOS) 24 bit ISA card Installs into your computer. Parts, plans, schematics and programmng available. Also may be purchased as a kit. 32 Bit Serial Receiver (57.6 K Baud TTL & CMOS) Parallel Port Relay Interface Circuit Reading Data From The Parallel Port 1 Second Time Base From Crystal Osc. 32.768 KHz Oscillator Using A Common Watch Crystal Digital Electronic Lock Telephone Circuits PIC Security System Dials Your Cell Phone Use Old Telephones as Intercom Telephone In-Use LED Indicator Telephone In-Use Relay Circuit Telephone Ring Generator Using 60Hz Power Transformer Telephone Ring Generator Using Switching Power Supply Telephone Audio Interface LED Circuits Philips RC5 IR decoder using 12 leds 1.5 Volt Dual LED Flasher 40 LED Bicycle Light (555 Timer - 6 volt) 28 LED Clock 72 LED Clock 10 to 100 LED Sequencer Using a Matrix PIC Digital Clock Timer PIC Digital Timer (4 timed outputs) Binary Coded Decimal (BCD) Clock Digital LED Clock and Timer Astable Multivibrator Expandable 16 Stage LED Sequencer Descrete Multistage Light Sequencer 16 Stage Bi-Directional LED Sequencer 10 Stage LED Sequencer 18 Stage LED Sequencer 9 Second LED Relay Timer 9 Second Digital Readout Timer Two Transistor LED Flasher 1.5 Volt LED Flashers LED Photo Sensor Circuit Fading Red Eyes Descrete LED fading circuit using 5 transistors PIC controlled Fading Eyes 12 Volt Lamp Fader (LEDs or incandescent) LED Battery Condition Indicator 3.6 Volt (cell phone) LED Battery Meter 8 Stage LED VU Meter Battery Equal Charge Indicator IR Remote Control Tester IR Remote Control Tester using a IR LED AC Line Powered LEDs Line Powered White LEDs LED Traffic Lights Analog / RF Circuits Temp Indicator (Window Comparator) Light Level Indicator (Window Comparator) Mechanical Wall Clock Quartz Synchronizer TRF AM Broadcast Receiver Superhet AM Broadcast Receiver AM Broadcast Loop Antenna LED Decibel Meter Whistle On - Whistle Off Long Loopstick AM Radio Antenna Micro Power AM Broadcast Transmitter FM Beacon Transmitter (88-108 MHz) Op-Amp Basics - The text information for the basic Op-Amp operation, 2nd order filters and bandpass filters was obtained in part from the paper back book "Design of Active Filters, With Experiments" by Howard M. Berlin, 1977. 3 Transistor descrete Op_amp Active 2nd Order Filters Bandpass Filter (Single Op-Amp) Low Power Op-Amp - Audio Amp (Intercom) Crystal Radio Circuits Simple Op-Amp Radio Low Frequency Sinewave Generator Low Frequency Wien Bridge Sinewave Oscillators Simple 3 Transistor Audio Amp (50 milliwatt) Improved 3 Transistor Audio Amp (80 milliwatt) RC Notch Filter (Twin T) Analog Milliamp Meter Used as Voltmeter hFE Transistor Test Circuit

Power Circuits Discrete Low Dropout Regulator. Buck Converter (1 watt LED driver) Boost Converter For Solar Cell Array Simple Variable Voltage Source LM317 Variable Voltage Regulator LM317 Regulator With Pass Transistor Variable 3 - 24 Volt / 3 Amp Power Supply Variable Voltage and Current Power Supply Lithium Ion Battery Charger using a 555 Timer, LM339 and TL431 Lithium Ion Battery Charger Using a TL431 And Single Transistor 2 watt switching power supply Low Power DC to DC Converter Constant Current Battery Charger 120VAC Lamp Chaser Using Solid State Relays 120 VAC Lamp Dimmer (full wave SCR) Varying Brightness AC Lamp 12 Volt Lamp Fader (Automatic) 1.5 Hour Lamp Fader (Sunset Lamp) Sunrise Lamp using 120VAC 60 Watt Lamp 12 Volt Lamp Dimmer (using a pot) Automobile Interior Light Fader Interfacing 5 volt CMOS to 12 volt loads Low Voltage , High Current Time Delay Circuit High Current Regulated Power Supply Thermostat for 1KW Space Heater (SCR controlled) Thermostat for 1KW Space Heater (Solid State Relay controlled) Miscellaneous Neodymium Magnet Single Pole Motor The Perpetual Swinging Pendulum Triangle and Squarewave Generator Transistor Schmitt Trigger Oscillator Descrete Set/Reset Flip Flop Discrete Bistable Flip Flop High Current MOSFET Flip Flop With Debounced Pushbutton Monostable Flip Flops (one shot) Ignition Coil High Voltage Circuit Ignition Coil Buzz Box Capacitor Discharge Ignition Circuit Generating Long Time Delays Flashing Neons (NE-51 / NE-2) Sequencing Neons (NE-51 / NE-2) 555 Tone Generator (8 Ohm Speaker) Generating Negative 5 Volts from 9 Volt Battery Touch Activated Lamp Game Show Who's First Indicator Lights Salt Water Battery Transistor, Diode, IC outlines Circuits Controlling Relays IR Receiver Toggle Switch Decoded IR Toggle Switch using the PIC12F629 Relay Toggle Circuit Using a 555 Timer Relay Toggle Circuit Using a 556 Timer Relay Toggle Circuit Using a Single Transistor and Push Button Relay Toggle Circuit Using a MOSFET and Push Button CMOS Toggle Flip Flop Using Push Button (CD4013) CMOS Toggle Flip Flop Using Laser Pointer 555 Timer Monostable Circuit Using Pushbutton Generating a Delayed Pulse With a dual 555 Timer Light Activated Relay (toggled) Photo Electric Street Light Power-On Time Delay Relay Circuit Power-Off Time Delay Relay Circuit Electronic Thermostat Relay Circuit AC Line Current Detector Pinewood Derby Finish Line Lights Pinewood Derby Finish Line Using a Computer - Scores times and places. Controlling relays with logic voltages ..........................................................................

Semiconductor Data Sheets

TI Semiconductors (search)	National Semiconductors (search)	Motorola
NTE	Datasheet Archive

Java Script Calculators

Resistor Color Code Calculator - Graphical resistor color code calculator by Danny Goodman. Uses pulldown menus and a realistic picture of a resistor.
4,5,and 6 Band Resistor Color Code Calculator - Graphical 4,5 and 6 band resistor color code calculator including tollerance and tempco.
Another Resistor Color Code Calculator - This one uses check boxes instead of pulldown menus and also calculates the equivalent value of two resistors in parallel. My own creation.
Ohm's Law Calculator - Java Script to solve Ohm's Law for Voltage, Current, Resistance and Power. Enter any two unknowns and solve for the other two.
Voltage Divider Calculator - Solves voltage, current, and power dissipation problems for two element resistive voltage dividers.
L or C Reactance Calculator - Java Script to calculate capacitive or inductive reactance and resonant frequency. For ideal devices only, resistance not included.
RC Time Calculator - Java Script to solve R and C values for given values of time or instantaneous voltages.
RL Time Calculator - Java Script to solve R and L values for given values of time or instantaneous current.
555 Timer - Frequency and Time Interval Calculator - Calculates positive and negative time intervals for the 555 timer based on R and C values. Also contains descriptions and operation of each input and output of the timer and schematics for the two basic modes of operation (monostable or "one-shot" and astable or "rectangular wave oscillator"). Also contains a pictorial diagram of the timer connected as a LED flasher and a table of connections for the 556 timer (dual 555 timer).
LED Series Resistor Calculator - Finds the series resistance needed for various series LED combinations and supply voltages.
Several JavaScript Calculators by John Owen. - Audio op-amp filter, Op-amp circuit, Decibels, Zener Diodes and more...
Air Core Inductance Calculator - Calculates number of turns and layers needed for air core inductors.
Gregorian Calendar - Displays any month from Oct 1582 forward.

Links to Other Hobby Electronics Sites and Useful Information

Don Klipstein's LED Website - Lots of useful LED information, FAQs, and sources for the brightest and most efficient LEDs.
Circuit Archive - University of Washington Circuit Archive, lots of good circuits and links.
Tomi Engdahl's Electronic Info - Links to a wide variety of analog and digital circuits.
Imagineering Imagineering On-Line Magazine,The Design Corner, over 100 circuits in pdf format.
Links for FM Transmitter Kits, Circuits, Electronics ...

Tony's Website - Free electronic circuits, R/C Gadgets, and tutorials for the hobbyist. Site in operation since 1995.
Steve Walz's FTP Site - FTP Resource Site, 1000 Files in 50 Directories.
Wenzel and Associates (Circuits) - Technical Library, Hobby Circuits.
Samuel M. Goldwasser Homepage - Silicon Sam's Technology Resource - FAQs, Links, Troubshooting & Repair, Laser info, Circuits.

Deep Cycle Battery Frequently Asked Questions

Wonton Soup Recipe This recipe was copied from a local Chineese take out place. Costs $5 to buy it, and only $2 to make it.

Commercial Electronic Sites, Kits and Projects Ramsey Electronic Kits Ramsey Electronics® has been providing the neatest electronic products and kits for nearly 40 years! From AM & FM Transmitters, Hobby Kits, Video Cameras, Time & Weather Products, Amateur Radio Gear, Mini-Kits, or just Neat Stuff Electronic Kits Store Offering a wide range of educational electronic kits, robotics kits, and electronic hobby projects. TheLEDLight.com Luxeon LEDs, LED bulbs, fixtures, flashlights, lanterns, clusters, arrays, and more... Lighting Components LED Corp. LED lamps, light bulbs, clusters and lighting components. JDR Microcontrollers Books, Kits, Test Equipment and more. Alltronics Electronic Kits KitZ Electronic Kits Electronics USA - LED Digital and Binary Clocks, LED Timers (Up and down counting), LED flashlights, and a few other items, as kits or assembled. Almost All Digital Electronic Kits Kits-R-Us Electronic Kits Microchip Technology Inc. (PIC) Controllers Online Components Worldwide shipping and over 350,000 part numbers in stock. Pad2Pad.com Custom Printed Circuit Boards. Free layout software and assembly service if needed. Express Printed Circuit Boards Download PCB software to layout your project, E-mail the resulting file and receive delivery of finished circuit boards via Federal Express in 3 working days. C. Crane Company LED Flashlights, windup radios, and other specialty items. This link space is available This link space is available Newsgroups sci.electronics.basics sci.electronics.components sci.electronics.design sci.electronics.repair ............................................

Electronics Educational Sites Making Electric Circuits And Electronics Projects. Making Electric Circuits And Electronics Projects. Includes theory, circuits, tutorials, and hobby projects. PIC Microcontroller Tutorial This tutorial explains the basic process of writing programs for the PICs and "burning" those programs to the device. A do-it-yourself programmer can be downloaded from David Tait's PIC archiveThe file you need is PIC84V05.ZIP. The file contains DOS software and programmer schematic that will work with PIC16C84, PIC16F84 or the newer PIC16F628, but will not program the full 2K ROM. It's limited to 1K. There is newer PIC programmer software for Win95/98/xP at WinPic that will program the complete 2K ROM (16F628) using Tait's existing hardware. Play Hookey Basic ideas about op-amps, analog circuits, optics, computers and digital logic. Electronics Tutorials A good comprehensive site with detailed examples and book recommendations. The Art of Electronics (Purchase the book) 1125 large format pages, 80 component-selection tables,1500 figures, extensive practical advice, back-of-the-envelope techniques, exhaustive 4000-entry index. LTSpice Version IV LTspice IV is a powerful free analog and mixed signal circuit simulation and schematic capture tool offering unmatched performance, speed and ease of use. LTspice is updated with new features, performance enhancements and device models on a regular basis. DC Circuits Department of Physics, University of Guelph. 555 Timer Circuits - All the electronics info you need to know about the 555 Timer. With over 80 circuits. All About Circuits - Electrical Engineering and Electronics Community. Electronic Component Suppliers 4 Star Electronics - Obsolete Electronic Components. Thousands of items, germanium semiconductors, obsolete ICs and memory, relays, switches, connectors, displays, and more. Mouser Electronics DIGI-KEY Corporation Allied Electronics Jameco Radio Shack Electronix Express - Components and test equipment for schools, colleges and industry. Very nice site. Bill's Surplus Parts For Sale- Resistors, capacitors, semiconductors and a few other items. I don't have a large inventory, just more than I need.

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For help with circuits not listed here, please post a message with details to one of the electronic newsgroups, either sci.electronics.basics or sci.electronics.design Many readers of those groups will offer ideas and a few specifics at no charge.

For help with specific circuits on this site, or some minor modification, please email the details and I will try to resolve it. I can also build completed circuits shown here for a small fee depending on time involved.

Please do not attach large files over 200K to email messages. I still use a dial-up connection with minimal bandwidth, and cannot download large files over 200KB.

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Copyright 1996 - 2016 (Bill Bowden)

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