Electronics Projects from Wolfden Press - Page One

Test and Measurement Instruments and Power Supplies

Page two contains Audio, Radio and Miscellaneous 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. Most images for the schematic drawings of the circuits are in PDF format.

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

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Projects List - Page One


Click for alphabetical list of all the projects.



Gauss Meter

Wind Meter

Infrared Tachometer

Frequency Counter

Function Generator/Frequency Counter
(Oscilloscope Traces)

Digital Volt/Amp Meter

Stroboscopic Tachometer

Capacitor Meter

Programmable Counter

Function Generator

Three Digit Counter

Frequency, Capacitance, Inductance Mater

Pulse Width Modulator

Crystal Tester (Transistor)

Ultra/Audio Tone Generator

Transistor Tester

1.25-30 VDC 3 Amp Power Supply

2 Amp Power Supply

1.5 Amp Power Supply

Dual Multi-Voltage Power Supply

Lux Meter

NE555 AF/RF Generator

Crystal/Oscillator Tester and
Frequency Counter

(Oscilloscope traces of crystal & oscillator)

LC Meter

Zener Diode Tester

Digital Oscilloscope

D32 Oscilloscope

Programmable Counter

Function Generator II

FG-500 Function Generator

Wave Generator

Tube Tester Schematic


Here is an alphabetical list of all the projects.



gauss

Gauss Meter
After some tedious work on the breadboard I finally got my Gauss meter to work just right. It measures from 1 to 1,999 gauss. A red LED indicates the north pole of the magnet being measured and a green LED shows the south pole. (See the schematic for details.) The gauss meter is built around the A1302 Linear Radiometric Hall Effect Sensor with a LM358 Op Amp to drive the LEDs and a 200mA digital panel meter for the readout. The meter reads minus (millivolts/gauss) for north pole and plus for south pole.

Glick here for the inside view.

wind

Wind Meter

The Wind Speed Meter is an electronics kit construction, built around a
programmable micro-controller PIC16F628-20. A pair of 40KHz sensors are
mounted on a "sensor handle". A signal is sent between the two sensors
and the change in frequency, caused by the wind, is detected and displayed as wind speed.

The kit for this project is available from Carl's Electronics (as Ultrasonic Wind Speed Meter Kit).
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f-count

This is my LED Frequency Counter.

This little frequency counter will read to 1 mHz (999,999 kHz) on the direct scale and up to 60 mHz on the X100 scale. The pre-scaler is a 74HC390 which has an upper limit of 66 mHz or so. The LED segments are .4 inches high and the enclosure is 5.5 in. wide so it makes a nice compact, portable unit. Here it reads 86.394 kHz from my little NE555 square wave generator.

Click Here for the schematic in jpeg format.

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f-count-in

Inside of the Frequency Counter.

The circuit uses BCD multiplex counters (MC14553) and decoder drivers (CD4543) with a MC4521 24 stage binary counter reducing the 4.1943 mHz clock to .5 Hz. The input signal is "cleaned up" and phased with the CD4093 hex inverter.
The current draw (with all zeros) is 36 mA so the 9 volt battery provides enough power. The on/off switch and wall adapter jack are on the left side.


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freqctr

My Function generator/Frequency Counter was built by combining two kits. The function generator is a kit from Jameco Electronics and the frequency counter is a kit from CallSaver Corp. It measures from 1 Hz to 50 MHz.

The schematics are in two parts - Function Generator, click image.

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frqfct

With the inside view you can see the two circuit boards and the controls. The power supply, controls and enclosure are supplied by me. The 9 volt battery powers only the frequency counter so it can be used portable (as with the IR Tach above or the Strobe Tach below).

For the schematic of the Frequency Counter click image.
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Here are a few oscilloscope traces of the three waveforms output from my functionn generator.
(These were read at a frequency near 20 KHz.)


sine

Sine Wave


tri

Triangle Wave

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square

Square Wave



el-v/a

Volt/Amp Meter - Label awaiting final assembly

Here is a volt/amp meter built with four seven-segment LED displays and driven by a ICL7107 A/D converter. This is my first project using LED displays. I used the 7107 datasheet as a guide and added a few components for reading volts AC and Amps. The -5v is supplied using a ICL7660 voltage converter.



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v/a-ct-bd

V/A Meter Circuit Board

Here is my V/A Meter circuit board. The ICL7107 takes most of the space but there are only a few resistors and capacitors along with the 7805 regulator and the 7660 voltage converter. The gray ribbon wire goes to the 7 segment displays.

Click image for the schematic in PDF format.


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bather

Stroboscopic Tachometer

      This one, I call my Stroboscopic Tachometer. The circuit design is not mine but the project is. The strobe flashes on a rotating object and the RPM can be read by adjusting the dial. With an accuracy of about 10% the ranges are 150 to 1700 RPM and 850 to 9000 RPM.
   Inside, the bright, white LED is mounted in a 3.5mm phone plug so I can use an extension cable. Also, a jack on the side provides access for reading the frequency directly with a frequency meter, an oscilloscope. This method improves the accuracy to about 1 percent.


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bathet

Click thumbnail for a larger view of the inside.
bathet Click for the schematic of this project (pdf).


cap-met

Capacitor Meter

       Don't we always need another way to read capacitor values? For me it was mostly the fun of building the circuit. My Cap Meter uses a 3 digit 7 segment LED display driven be a MC14543 and multiplexed with a MC14553. The clock, reset and latch are controlled with a CD4049 and a CD4011.
    The 4 position 3 pole rotary switch selects the measurement ranges from 10 picofarads to 100 microfarads. A X10 extender will boost the upper limit to 10,000 uF (9,999).
I used a 16 pin DIP socket and banana plugs (with short leads) to connect my capacitors.
Here, I'm measuring a 470uF electrolytic on the 1-999uF scale.





cap-tm

Click for a larger circuit board view.


cap-tm

Click for the schematic view.



4dig

Programmable Down Counter

My down counter can be starter with any number from 9999.
When started it will count down to 0000 which triggers the alarm
piezo buzzer. The circuit design is not mine but the project is.
The kit number CK1613 (DIY Kit 154) that I built for this project
was from Carl's Electronics.

Click Here for the description of this kit at Carl's Electronics in Oakland, CA.


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4dig-in

Inside the Counter

The green pc board is the counter which includes the set
and increment buttons. The brown circuit board is my
one second clock and alarm, both built using 7555 timer ICs.
The timer will operate with the 9 volt battery or a wall adapter.
The circuit draws only 20mA.

Click Here for the schematic of the 1 second clock and alarm circuit (pdf).

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bather

Function Generator
This was the first Function Generator I built based on the XR-2206 IC. I learned about wave shapes and frequencies by using this with my oscilloscope. I liked this one so much that I built the Function Generator/Frequency Counter shown above.

Click image for a larger view.

For the schematic see the Function Generator above.

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ps1.5

1.5 Amp Power Supply
And yet another power supply. When I built the 2 Amp power supply I inadvertently applied the incorrect voltage to the meter terminals, frying it. I bought two more meters and ended up with one extra. So this PS came out of the extra meter. This uses a LM317 adjustable voltage regulator so the circuit uses few parts. The power transformer is a desk-top power supply from a printer - its output is 24vdc at 1.5a.

Click image for the schematic

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3dig

Three Digit Up Counter

My three digit counter will count up from 000 to 999
in 1 second intervals (the equivalent of 16.6 minutes).
It is handy for timing the duration of certain projects such
as: how long have I been sanding this paddle?. The circuit for this counter is based on the MC14553, a 3-digit BCD
counter and the MC14543, a BCD-to-7-segment latch/decoder/driver.
The one second clock circuit in this counter is a modified
version of the clock circuit in my four digit counter.






3dig-in

Inside the Counter


3dig-sch

Click here for the schematic of this counter (pdf format).


fcl

Frequency, Capacitance, Inductance Meter

This instrument will measure frequency, capacitance and inductance. The LCD display is backlit so it is easy to see the characters. The rotary switch, in frequency, can select F, 10, or 100 through my frequency divider circuit. This gives me a range to 50mHz. The meter was originally designed to read 5 mHz. However, a manufacturing flaw limited it to 500kHz. For this reason I acquired it at a very low cost.
The ranges for C and L are from 10pF to 10uF in capacitance
and from 10uH to 20H in inductance.



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fcl-tm

Ckick here for the inside view.



fcl-tm

Ckick here for the wiring diagram of the divider and selector.



bather

Pulse Width Modulator
This is my Pulse Width Modulator demonstrator.The square wave it puts out is adjustable in duty cycle from 10% to 90% with a frequency of 1200Hz and an a 8 vdc output voltage. It will drive a small DC motor. The one I used came from a dismantled printer. It turns between anout 10 and 750 RPM. The varying pulse width output can be seen on an oscilloscope as the speed is increased or decreased.

Click image for a larger view.

Click Here for the schematic.



bathet

Crystal Tester
The crystal tester shown here is built with a two transistor circuit. It is used for testing the type of crystals found in RC models, etc. The green LED will light up if the crystal under test is oscillating. Also, there is a output jack so the frequency of the crystal can be read on a frequency counter or an oscilloscope. The npn transistors are not critical but they need to have a hFE (current gain) of about 200.

Click image for a larger view.

Click Here for the schematic.
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dual-multi

Dual Multi-Voltage Power Supply
Here I have squeezed in another little power supply. This one is dual voltage (for positive and negative voltages) and is selectable for 5, 9, 12 and 15 volts. The circuit is built around two voltage regulator ICs, a LM317 for positive and a LM337 for negative voltages. The case was salvaged from a failed 1 Amp battery charger.

Click image for the inside view.

Click Here for the schematic.


ultra

Ultra/Audio is a tone generator that operates through the audio frequency range and into the ultrasonic, 50Hz to 45KHz.
The "sound" can be heard from the piezo speaker (at low frequency)
or with a bat detector. It can also be measured with a
frequency counter or an oscilloscope.

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tach

The Ultra/Audio circuit operates on 18 volts (2 - 9V batteries). The frequency adjustment is a ten-turn pot that allows for fine tuning. The output is selectable for "Low" 50Hz to 2500Hz, and "High" 2200Hz to 45KHz. The output is either a triangle or a square waveform.

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ultra

Transistor Tester.

My transistor tester helped me identify
a multidude of transistors that were salvaged from a
variety of junked electronic equipment.

The Transistor Tester Inside, the components are rather hard
to see but they consist mainly of a couple of transistors, resistors,
switches, a speaker and battery. Click the image to see
the schematic in pdf format.



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gang

Gang of Instruments

     Here are a few instruments on my work table. I set these up to test my new FG-500 Function Generator. All the waveforms are nice and clean. This one, shown on the D32 scope, is a triangle wave at a little less than 100 Hz.
     For more about the FG-500 Function Generator go to FG-500.


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ultra

Power Supply
This is very useful when working on projects.
It supplies voltage from 1.25 to 30 VDC at up to 3 amps.

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tach

Power Supply Inside
The voltage adjustment is made through a LM723 voltage
regulator and the output is through a 10 amp MJ3001 Darlington
Transistor. The analog V and A meters are direct coupled.

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ps2

2 Amp Power Supply
Here is the same power supply as above, built in a smaller package. This one has digital panel meters. The schematic for the main power is the same as the power supply above so I did not redraw it here. The meter operation is quite different. It supplies voltage from 1.25 to 30 VDC at up to 2 amps. Here it reads 10 V at 200 mA with a 50 Ohm load connected.

Click image for the meter power schematic

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ps2in

2 Amp Power Supply Inside
The power supply in this enclosure becomes quite compact. The digital meters are shown with their scaling resistor circuit boards attached. The batteries provide power for the meters. They are switched on with the small relay just above the transformer.

Click image for a larger view

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cx1

I built my crystal tester to test some crystals and can oscillators which bounced around in my parts box for a long time. The frequency counter in this project displays the frequency for the crystals and oscillators and also functions as an independent frequency counter. Its range with the prescaler circuit is from 10 Hz to 600 MHz. The counter section is built from a kit by DIY Electronics.

Click image for a larger view.
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cx2

Inside the crystal/oscillator tester, the circuit is quite simple. The crystal test is built around a MC14060 binary counter IC shown in the left side of the picture. The frequency counter PCB is at the top right and the rest is switches and the sockets for the can oscillators. The circuit will operate from the 9 volt battery or a 6 - 12 volt wall adapter. It draws 12 mA on standby and 35 mA on test.

Click image for a schematic drawing in pdf format.
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cx2

Here is an oscilloscope trace from a can type oscillator. (It can be seen on the tester in the above picture.) The frequency read here is 11.289320 MHz.

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cx1

This trace, also read from my crystal/oscillator tester, is a crystal similar to those used in r/c transmitter/receivers. This one is being read at 5.767680 MHz.

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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.

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lux

Lux Meter
I decided to replace the #1141 bulbs in my travel tariler with leds, to reduce battery drain. I built one with 24 warm white 17,000 mCd leds, I needed a light meter to measure the luminesance of the bulb vs. the leds. This project, I built from my electronic junk boxes. The meter is from an old SWR meter and the solar cell was once part of a camera light meter.

Click here for the schematic.

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lc

L/C Meter
Some of the frequency oscillators I build require very small value capacitors and inductance coils. I bulit this Inductance/ Capacitance Meter from a kit available at DIY Electronics. It is built using a 16PIC16F628 Microcontroller and has autoranging. The inductance range is from 10nH to 100mH and the capacitor range is from 0.1pF to 900 nF.

Click image shows the circuit board and inside view, and here for the schematic.
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zen-test

Zener/Diode Tester
   Some of the diodes in my parts box are really zeners (without identifying numbers). In order to find out the breakdown voltage of these, I built a Zener/Diode Tester. It uses a 9 volt AC transformer (in reverse) and a NE555 timer IC. Also, a volt meter. The zener tester will also test regular diodes. I used the same enclosure as the LC Meter.

Click image shows the circuit board and inside view, and here for the schematic.
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d-scope

Digital Oscilloscope

   This is my Digital Oscilloscope. Here it is reading a 1KHz sine wave signal from my function generator. It comes as a Kit from CanaKit, Model #DSO 062 at: Canakit.com. Details and specifications can be found on the JYE Tech website at: JYETech.com It is small (pocket size) and has a 2" screen. This little scope works quite well for its size. It will measure up to 1MHz on the scope and 5MHz on the frequency counter. The kit does not come with a case, I added that. Inside is a frequenzy divider that is configured to divide by 10 or 100, allowing me to read frequencies up to 100MHz on the scope and 500MHz on the frequency counter.

Click image for a larger view.
Click here for the Frequency Divider wiring drawing in pdf format.
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func-gen

Function Generator II

   My new Function Generator was built as a complimentary to the Diggital Oscilloscope. Based on the XR2206 IC, it is essentially the same circuit as the one near the top of this page but it's in a more compact package. I pushed the 2206 to almost 2MHz. It has Sine wave, square (sync out 1/2 and full swing, and triangle wave output. Amplitude on the sine and triangle is variable, 0 to 4 volts and on the square is 2 volts, 1/2 swing and 4 volts at full swing. Power is supplied with a 12 VDC wall pack.


Click image for a larger view.
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elef

Elenco Function Generator.

     Just for fun I decided to build the FG-500 Elenco Function Generator. The circuit is based on the XR2206 monolithic function generator IC, but is a slightly simplified version of my function generator circuit above. The kit is easy to build and it displays good, clean waveforms.
I made a few hardware changes, used BNC connectors instead of banana plug jacks, used a larger ext. power jack and added a LED indicator.

Click here for the schematic in pdf format.



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tach

Infrared Tachometer

This is my Infrared Tachometer. It will read the RPM of almost anything that turns. It is not a complete tach in as it needs a means to display the RPM. For this, the alligator clips are connected to a frequency counter.

Inside the tachometer, you can see that it is an uncomplicated arrangement. The IR is transmitted from the IR LED, bounced off reflective tape on the rotating object and the reflection is received by the IR sensitive photo-transistor. Frequency X60=RPM.


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wavegen

Wave Generator

      Many years ago I built an electronic keyboard to play music. I used 12 LM566 voltage controlled oscillator ICs to generate the high octave tones for the chromatic scale. These tones were then divided down to the lower octives for a five octive organ keyboard. Here I have used one of these 566 ICs to make my Wave Generator. It produces a square, triangle and sine wave at from 50Hz to 1mHz. The circuit is quite simple and straight forward. It uses the IC and some additional components.


wavgen

Wave Generator


wav-ct

Circuit Board


sch

The Schematic

Ckick for larger images


tubeamp

Vacuum Tube Tester

    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.

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