Dick Cappels' Project Pages
Questions about projects on this site gladly answered.
(Address is an image -please type it in.)

click on link below to
          go to the original website or to remove frame. URL is


June 2017

Microcontrollers, Analog, RF, and all three mixed.
Most projects can be assembled from readily available parts without the need for specialized equipment. My hope is that you will find these projects helpful, and at least be able to make use of some of the bits and pieces you will find among them 
Test and Measurement

         Voltage Recorder With Playback (ATMEGA48V)

         A Simple Attenuator And Preamp For DC Measurements  (Analog Only)

          A X1,000 Microvolt Amplifier -input range is 2.5 mv (Analog only)

         A X100 Microvolt Amplifier (Analog only)

An Inductance Measurement Adapter For Digital Voltmeters       

An Even Better LC Meter Based on Atmel AVR  ATTINY861

A Pretty Good LC Meter Based on an AVR (ATtiny2313, AT90S2313)

A Simple Manual Curve Tracer (analog only) 

A Photocell Amplifier for Comparative Light Measurements (analog only)

A 10 Bit LED Digital Panel Meter With Auto Ranging Based on ATMEGA 8   ATMEGA8

An Isolated Variable AC Mains Transformer

MAX038 Function/Sweep Generator with Markers (ATtiny2313, AT90S1200A)

A Noise Generator per IEC 268-1, IEC 268-5, and IEC 268-7 

1.000 kHz Sine Wave Generator  ATTINY2313/AT902313/ATMEAG8515/AT908515, etc.

LED Wink Tester For 1.5 Volt Cells

Battery Voltage Checkers 

LC Determination by Resonant Frequency Measurement (ATtiny2313, AT90S2313)

Inductance meter for RF Inductors

HF/VHF/UHF Test Oscillator

A Little More Serious Frequency Meter/Counter(ATtiny2313, AT90S2313)

A 300 MHz  Prescaler and 30 MHz preamp for A Little More Serious Frequency Meter

Frequency Meter and Pulse Generator (ATtiny2313, AT90S2313)

WATTMETER (uses DVM for display)


Digital Lock-in Milliohmmeter (ATtiny2313, AT90S2313)

HF AC Millivoltmeter adapter

Precision Audio Frequency Peak Detection Probe

Digital RF Field Strength Indicator (ATtiny2313, AT90S2313)

An RF Field Strength Meter Using A Biased Schottky Deterctor and  A Moving Coil Meter

A Field Strength Indicator -Analog only.

RF Field Strength Probe (AT90S1200A)

LTD - Low Cost Telemetering Device; ATMega8 scanning voltmeter with Morse Code output (ATMega8)

Waveform Monitor with LCD (ATtiny2313, AT90S2313)  

Simple LM335 thermometer

A Precision Portable Voltage Reference

AC Current Probe for Oscilloscope Use.  

Low Capacitance Scope Probe Adapter 

LED Driver circuits

White LED drive from 1.5V   MARCH 2018 -NEW CIRCUIT

Attention-Getting Auxiliary Warning Light Flasher/Driver 

A One Watt White LED Power Supply Light For Battery Powered Operation

White LED inductorless drive from 1.5V and 3V

R/C Model Aircraft Marker Light Flasher
  (ATTINY12 and others)

Fast precision LED driver

Flying inductor LED series voltage boost circuit. (Power supply in series with the battery and LED)

White LED Night Light For The Home

White LED Power Failure Light

White LED Stroboscope With Constant Duty Cycle and Constant Current Drive

1.5 Volt 1970's Style Caboose Marker Flashing Red LED Light.

Simplest LED Flasher circuit 

         An Array of 180 UV LEDs

LCD Drivers (firmware)

Serial Interface for Truly MTC-C162DPLY-2N, 2 line X 16 char LCD display (AVR controllers with RAM)

Serial Interface and bias supply for Seiko-Epson G1216B dot graphics display (ATtiny2313, AT90S2313)

RF and Communications


7 Bit Barker Code Generator Circuit With RC Clock Oscillator
The Phone Catcher -see when your cell phone is transmitting  (Analog only)

A 330MHz Remote Control With A Simulated Princeton Technolog PT2264 ATTINY2313

A Simple FM Stereo Transmitter    (ATTINY12, ATTINY25, ATtiny2313, AT90S2313, AT90S232, or nearly any other CMOS microntroller-Yes probably even a PIC!)

FM Transmitter With Crystal Referenced PLL Frequency Control Using LMX1601 (ATtiny2313, AT90S2313) 

FM Broadcast Audio Transmitter

Battery operated FM rebroadcast transmitter

100 MHz modulated RF source for FM Band

90 MHz voltage controlled oscillator for FM Band

Minimum Mass Wireless Data Coupler-Near Field Communications (NFC)

Terminal Interface with Minimum Mass Wireless Coupler (ATtiny2313, AT90S2313) -Near Field Communications (NFC)

Scanning Voltmeter with Minimum Mass Wireless Coupler ATMega8)-Near Field Communications (NFC)

Frequency Meter with Minimum Mass Wireless Coupler (ATtiny2313, AT90S2313) -Near Field Communications (NFC)

LCD Display with Minimum Mass Wireless Coupler  (ATtiny2313, AT90S2313)-Near Field Communications (NFC)

Tiny Tuned Loop Antennas for the Minimum Mass Wireless Coupler-Near Field Communications (NFC)

Digital wireless for the bench top (ATtiny12) 

RS-232 to Wireless Instrument Data Channel (ATtiny2313, AT90S2313)

Frequency meter with wireless Data Channel (ATtiny2313, AT90S2313

4 MHz amplitude modulated RF source

1 W Experimental Output and 1 Meter Loop Antenna for 187 kHz (Lowfer)

1750 Meter Lowfer Band amplitude modulated RF source (ATtiny2313, AT90S2313)

A Dual Mode Superhet/Direct Conversion AM receiver for 181.818 kHz (Lowfer) (ATtiny2313, AT90S2313)

MK-484 Receiver Chip Evaluation Board for AM and Lowfer bands.

Programming Tools and Techniques

AttoBasic Home  ATMEGA32u4, ATMEGA88 ATmega 168m,ATmega328,AT90S8515/ATMEGA8515, ATmega163, andATtiny2313 /AT90S2313 


AVR Firmware Monitor Program   (AVR Controllers with on-chip UART)

Minimum Mass Waveform Capture with AVR       (AVR controllers with RAM)

DS: Firmware based protocol for low priority data transfer

DS: Test and development tool for DS interface (ATtiny2313, AT90S2313)

DS: Clock/Calendar/Alarm with EEPROM-based interpreter and DS Interface (ATtiny12)

DS: 3 channel 8 bit EEPROM DAC with DS interface (ATtiny12)

ATtiny12 Fuse Restorer (AT90S1200A)

EEPROM Driver for 24LC64, 128, and 256 (AVR Controllers)

8 Channel PWM PWM Code (AVR Controllers)

AVR Serial Programmer (AT90S1200A, ATtiny2313, AT90S2313)

AVR 8 and 20 pin programming adapter

A ZIF ISPAdapterfor up to 40 pin AVR controllers 

Lazy ISP Adaptor for Socketed AVR ISP Controllers

Decoding 4 buttons with 2 I/O pins   (Controllers with tristate I/O ports)

ANALOG (other)

Circuit Design: Linear Inductance or capacitance to voltage converter

Flying Battery Voltage Doubler / Power Supply Splitter


Avalanche Breakdown Photoemission and the Photoelectric Effect in Bipolar Transistors


A DC to 20 MHz amplifier

An Experiemental 1 kHz Inductance Meter ATTINY861    

          An Experimental Triac Lamp Dimmer and Motor Speed Control Using A Simulated Diac

Electrete Condenser Microphone Line Level Preamplifer Powered by USB

Barker Code-Locked Loop Synchronous Demodulator(ATtiny2313 or AT90S2313, ATtiny12)

A Regulated 24 Volt Output, 5 Volt Input DC To DC Converter

Half-flying capacitor analog multiplexer for microcontrollers (AVR Controllers or other with tristate I/) pins)

Single Pulse Voltage Multiplier

EDFET Buffer.

Experimental 1 kHz Synchronous Demodulator (ATtiny2313, AT90S2313)

Audio noise generator drives earphones or small speaker

Specialty Projects
A USB Grounding Adapter
Switchable 15 Watt Resistive Load For 120/240 VAC

Garden Watering Timer (Gates and counters; no microcontroller)

USB Printer Sharing Switch

Door chime Privacy Sentry (ATtiny12)

Morse Code Alarm Clock modification with ATtiny2313/AT90S2313

Bedwetting alarm

Tips, Notes, and Techniques


Toroid and Ferrite Bead Winding Notes


Special Stuff

Some Selected Web Links

Here are a couple of good datasheet sites. They seem to be somewhat better than the older ones.

http://www.cappels.org  Main entry to cappels.org

A note about privacy

(Any sponsored links below are not endorsements.)

(Summary: No warranties, use these pages at your own risk. You may use the information provided here for personal and educational purposes but you may not republish or use this information for any commercial purpose without explicit permission.) I neither express nor imply any warranty for the quality, fitness for any particular purpose or use,or freedom from patents or other restrictions on the rights of use of any software, firmware, hardware, design, service,information, or advice provided, mentioned,or made reference to in these pages. By utilizing or relying on software, firmware, hardware, design, service,information, or advice provided, mentioned, or made reference to in these pages, the user takes responsibility to assume all risk and associated with said activity and hold Richard Cappels harmless in the event of any loss or expense associated with said activity. The contents of this web site, unless otherwise noted, is copyrighted by Richard Cappels. Use of information presented on this site for personal, nonprofit educational and noncommercial use is encouraged, but unless explicitly stated with respect to particular material, the material itself may not be republished or used directly for commercial purposes. For the purposes of this notice, copying binary data resulting from program files, including assembly source code and object (hex) files into semiconductor memories for personal, nonprofit educational or other noncommercial use is not considered republishing. Entities desiring to use any material published in this pages for commercial purposes should contact the respective copyright holder(s).

Portions copyright 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 1014, 2015 and 2016 Richard Cappels All Rights Reserved. http://www.projects.cappels.org/