Wolfden Press Electronics

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Electronics Projects from Wolfden Press - Page Two

Audio, Radio and Miscellaneous circuits

Page one contains Test, Measurement and Timer circuits.
Page three contains some of the Instruments I have used.

Some of these projects were gleaned out of my own experimentation while others are built from available kits.
Build at your own risk. Click most images for a schematic drawing of the circuit in PDF format.

Try the Capacitance Converter. Click Here, its on a separate page.

Site Directory

Airplane Models

Dave's Lobster Boat

My Other Web Sites

Projects List - Page Two

Click for alphabetical list of all the projects.

Audio Visual Bat Detector

Bat Spy (Recorder)

Binary Clock

LED Binary Clock

Panel Meter Clock

Three Digit Counter

Strobe Light/Siren

Magic Conjuring Board and Magic Wand

Bat Call Simulator

Aircraft Band Receiver

The Bat Listener

Model Train Throttle

30 Watt Stereo Amplifier

Infrared Detector for a Model Train

Heterodyne Bat Detector

Derek's Train Sounds

FM Transmitter & Receiver

Wildlife Listener

3 Watt Audio Amplifier

Tube Amplifier Circuits

Tube Tester Schematic

el-av

A/V Bat Detector
My audio/visual bat detector. With this gadget you can hear the bat call and see the flashing LEDs at the same time. When a bat call comes in, the LEDs will light relative to the frequency received. One LED = 20KHz, eight LEDs = 80KHz.

avocet

AV Bat Detector Circuit Board
The circuit board is wired on the top surface (because I build most of my projects only once, I use copper clad project boards instead of printed circuit boards) with some lands and buss connections of the under side. The audio section is on the green board and the video on the brown board.

bathet

Bat Spy (Recorder)
Bat Spy is not actually used to spy on bats but rather to record their chirps and buzzes while using a bat detector. It is built using a 20 second (pre-built) digital recording module with the push-buttons, microphone, speaker and LED added. To record bats I hold it near the speaker of my bat detector and press record. It will playback through the speaker or directly into my computer audio analyzer program.

Click image for a larger view.

bathet

FM Transmitter II
This FM Transmitter is from a kit by Cana-Kit. It is based on the IC BA1404 and will operate on a 9 volt battery. I am using mine with a 9 volt wall adapter. The circuit is different than the FM transmitter further down this page although it uses the same IC. This transmitter has a range of about 200 ft.

Click Here for the schematic in PDF format.

ultra

Here is another strobe project, but this one flashes 16 ultra-bright
LEDs and has an audio section to produce a siren effect.

Click makes image larger

tach

The circuitry for the Strobe/Siren is based on 4 ICs. Flash rate
and duty cycle for the LEDs is adjustable, as is the siren level.

Click image for a schematic in PDF format.

A few interesting electronic clocks

ultra

MintyTime Binary Clock

This clock is actually BCD (binary coded decimal).
Each column is a binary set with the LED in on/off state.
It reads time in the 24 hour format and here shows 23:51 hrs.
The green LED simply shows 1 second pulses.

Click image makes it larger

This binary clock uses a ATtiny2313 micro-controller IC and a 74HC595 comparator for control and includes a LED dimmer and pulse width modulation to conserve power. It operates on two AAA batteries.

Here are two pictures of the same binary clock circuit built in a portable case.

tach

Clock circuit board

This clock comes in a kit and is designed to fit in a
Altoids can. Here I have mounted it on a piece of
plastic. The kit can be ordered from www.mintytime.com
It is easy to build with full instructions on their web page.

Click image makes it larger

led-clk

LED Binary Clock

My LED Binary Clock reads the time in 24 hour format from right to left. Binary numbers read from right to left. The top row reads the hour from 1 to 23. The center row reads the minutes from 1 to 59 and the lower row reads the seconds to 59. After the seconds row reaches 59, the next count switches the minutes up by one binary number. The same happens between the minutes and hour rows of LEDs.

Click for schematic in JPEG format

Here is a closeup of the circuit board

And here a woodworking tip from the Wolfden

led-clk

Binary clock circuit board

Here is the circuit board for my LED Binary Clock. The three button switches are for setting the time (hours, minutes and seconds) when the (slide) mode switch is in set position. After setting, the mode switch is put in run mode. This is a test setup, as my breadboard still has the battery back-up diodes and the dimmer circuit on it.

led-clk

Panel Meter Clock or Chronulator

Here is another clock that I find quite fascinating. It is built with analog panel meters. This one comes as a kit from Alan's Electronic Projects. The PIC is a 16F628A and the clock pulses are generated using a 20mHz crystal. I used 1mA meters with the appropriate current resistors instead of his 500uA meters. And, mine is built in a simple wood case instead of the attractive "Simpson 260" case that Alan built for his clock.

led-clk

Circuit Board and Meters

Here is the circuit board for my Panel Meter Clock. The three tactile switches are for making the initial meter settings and for adjusting the time (hours, minutes and seconds). The circuit is built on a perf board from the schematic provided by the maker on his web site. The meters are builder supplied. The kit comes with the pre-programmed PIC. It is powered with a 9 VDC wall pack and the batteries are for back-up.

Click for the schematic by Alan Parekh in PDF format.

The Meter Clock before being installed in the wood case.

The Meter Clock with Larger (2½")Meters. Built with the same circuit.

magic

Magic Conjuring Board with Wand

I found the circuit for the Magic Conjuring Board on the DIY Electronic Projects website (the Magic Wand Conjuring Trick by Rev. Thomas Scarborough). My circuit differs in that I have added the timer and decade counter ICs, and 10 LEDs to flash in a circle and a piezo speaker for sound effect. When the right combination of buttons is passed over with the magic wand the LEDs (red, white and blue) flash around the circle and the buzzer sounds.

Click image for a larger view

u-magic

Under the Conjuring Board

When the magic wand (with a magnet imbedded in the end) passes over reed switches S4, S5 and S6 (see Schematic) in that sequence, it makes the output of the CD4081 high which turns on the transistor that feeds power to the LED circuits. S1, S2 or S3 will turn off the LEDs if passed over at any time. The reed switches can be placed at any location under the board that will make the conjuring trick interesting.

Click image for a larger view

bread

Breadboarding the Conjuring Circuit

After much experimentation with component values I finally got the circuits to operate well. The CD4081 is a Quad AND gate which turns on/off depending on which inputs are high and low. The CD4093, a Quad NAND gate, functions as a clock to drive the LED circuit at 15Hz and the piezo speaker at 460Hz. The CD4017 is a decade counter. It drives the LEDs in their flashing sequence. The complete circuit draws about 5mA in standby and 15mA operating.

Click image for the schematic

ultra

Bat Buddy produces a kind of simulated bat sound
in ultrasonic, a series of clicks at 40kHz that can only
be heard with a bat detector.

tach

Inside Bat Buddy is an IC that generates three
frequencies which are then mixed in a binary divider
and amplified for the 40kHz output transducer.

ps1.5

The AR2 Receiver

Here is the Ramsey AR2 aircraft radio receiver. It receives the 118 to 136 mHz band and will scan for active frequencies. The scanner has several programable features including full scan, skip scan and memory scan. The front mounted speaker is small but a good headset will provide great sound.

el-bat-list

The Circuit Board
This little circuit board, about 4"x6", contains 160 components. The assembly procedure is very straight forward and all parts fit just the way they should.

Click Here for the schematic in PDF.

el-bat-list

The Bat Listener
I call my new bat detector The Bat Listener. It is a heterodyne, using ideas of two other designers. The pre-amp, mixer and output are from the Tony Messina Bat Scanner and the local oscillator from a circuit by Bertrik Sikken. After prototyping and testing I came up with a good working (manual tuning) bat listener. The sensitivity almost equals the Bat Scanner with minimal background noise. The enclosure was once a printer power supply.

listener

Here is a handy little audio Amplifier that puts out 3 watts of power. After building it with 4 tarnsistors I added a preamp using a LM358 op-amp. Click image to see schematic.

thro

A DC power controller for model railroad. This one is built
around a LM350K 3 Amp power voltage regulator.

thro

Inside the train controller (a bit of a rat's nest).

thro

This project is a Stereo Amplifier that I decided to build from several kits. It performs very well with a tape deck and with a record turntable. The output sound is best with a good pair of 4 Ohm speakers.

Click this image shows a schematic of the power supply, power amp and the LED VU meter.

thro

Inside the stereo amp is the power amp, a Velleman Kit K4003, the LED VU meter, a Velleman kit K4305 and the tone/volume control, a Kemo Germany kit #18-192. The preamp uses a TL082 dual op-amp and was home built.

Click this image shows a schematic of the preamp and the stereo tone/volume control.

rr-ctrlr

My Model Railroad is an "N" scale layout called "The Kamloops Line". You can see the track plan in this picture. The 14 turnout switches are used to change the route a train takes. Red or green (bi-color) LEDs show the position of the turnout. Other controls are for lighting, accessories and Digital Command Control.

The complete layout can be viewed on my www.sashart.org website.

irdet

This little circuit is a Infrared Detector. It includes LED flasher and bell circuits and was built to operate the grade crossing lights and bell when the train rolls by. The transmit and receive circuits are from a Jameco Electronics kit (the ir transmit circuit in not shown here). I added the 5 volt regulator components and the relay, and built the flasher for the crossbuck lights. The bell circuit is at the upper left.

Click image for schematics in PDF

bather

Larry's version of the Heterodyne Bat Detector.
This one works like an AM radio except that it receives
bat calls instead of music.

Click makes a larger image

bathet

Inside the Heterodyne Bat Detector
Go to Bats of Williams for more of
Larry's bat detectors and other batty stuff.

No schematic for this one

dtr

Derek's Train
This one is for Derek. It has three train sounds,
a whistle, bell and the clackity clack of the railroad track.

Click image for a schematic drawing.

sqwave

AF/RF Generator
Here is my square wave AF/RF generator. It is made
with a NE555 timer IC and produces a frequency from
65 Hz to 75 KHz.

Click image for a schematic drawing.

fmtr

FM Transmitter
Here is my FM stereo transmitter. It connects to the audio out jacks on my TV and transmits the sound to my FM receiver for personal listening. This one is built from a kit available at Jameco Electronics.

Click image for schematic drawing in pdf.

fmrec

FM Receiver
The FM receiver was built from a Ramsey kit. It is a perfect companion to my FM Transmitter and has enough power to drive a good size speaker but it works well with an earphone. It operates on a 9 volt battery or a wall adapter.

Click image for a schematic drawing in pdf.

listener

The Wildlife Listener is a high gain audio amplifier. It's great for listening to bird songs and other interesting critters.

listener

Inside the wildlife listener are two integrated
circuits, an LM1458 op-amp and an LM386 amplifier.

This was one of the first schematic drawings I made of the amplifier that I wanted to build. The power supply is not shown but eventually, I found another plan. I had lots of parts and boxes full of tubes so I felt that I could build just about anything.

Click image for a larger drawing in JPEG format.

tubeamp

Here is the schematic of the first stereo amp that I built, in the early 1960s. (The original drawing is too light to scan, so I did a redraw with Design Works.) Most of the parts were salvaged from discarded TV and radio chassis that I found behind repair shops. They were happy to have me take them away. I listened to my first Stereo records with this amp and was thrilled with the sound.

Click image for a full size drawing in PDF format.

amp

Here is another tube amp. This one is a momophonic amp with two inputs, one standard mic input and the other for guitar.

tubeamp

This schematic is for a Vacuum Tube tester. As I was fixing lots of TVs, and the tubes were most often the culprit, a portable tester was very handy. So, I borrowed the manual, copied the schematic, and built my own. It worked great for many years. That is, until transistors and integrated circuits took over.

Click image for a full size drawing in PDF format.