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Wednesday, March 19, 2008

Sound Level Meter


This is a one chip sound level meter that can be use for displaying sound level of an amplifier or simply the sound level from a microphone.The heart of the circuit is IC LM 3915 Audio level IC.Even though it is a stand alone IC , a peak detector based on Transistor BC 558 and diode 1N4001 is also included for better performance.


Supply voltage can be from 3V to 20V.The input is set for audio line voltage (1V peak to peak) and has a max input voltage of 1.3V. To make the circuit use a moving dot display instead of bar graph display,Pin 9 can be should be disconnected from +V.

Parts List.
C1 2.2uF 25V Electrolytic Capacitor
C2, C3 0.1uF Ceramic Disc Capacitor
R1, R3 1K 1/4W Resistor
R2 10K 1/4W Resistor
R4 100K 1/4W Resistor
R5 1M 1/4W Resistor
D1 1N4001 Silicon Diode
Q1 BC 558 PNP Transistor
LED1-LED10 Standard LED or LED Array
U1 LM3915 Audio Level IC
MISC Board, Wire, Socket For U1

19 Watt Amplifier using LA 4440


This is the circuit diagram of a simple 19 watt amplifier using IC LA4440 from Sanyo.It uses very less components other than the IC LA4440.A very high quality circuit with respect to its cost and ideal for beginners.

Here IC LA 4440 is wired as a bridge amplifier to deliver a 19 W Rms on a 4 Ohm speaker. The IC has built in thermal, over voltage and short circuit protection.The IC also incorporates a audio muting function,but that is not used here.

Notes .

  • Use a 12 V DC power supply able to deliver at least 3A current . IC can with stand up to 25 volt , but I prefer it should not be nothing more than 16V.
  • Don’t forget to fit a proper heat sink with IC.
  • Assemble the board on a good quality PCB.Carefully understand the specifications of LA 4440 given below before proceeding
  • Use a 4 Ohm speaker as load. 8 Ohm speaker can also be used but the power output will drop to half (9.5 W) .
  • For stereo assemble two copies of the amplifier given here.

18 W MOSFET Amplifier Circuit


This circuit is an audio amplifier capable of delivering a decent output power with a minimum no: of parts , with considerable sound quality.

The amplifier employs only two transistors one MOSFET and few resistors and capacitors in a shunt feedback scheme.This tiny circuit can can deliver a whopping 18Watts into 8 Ohm speaker or 30W into a 4 Ohm speaker.

To get such a good performance and stability out of this this much few components a high quality well regulated DC power supply is necessary. This is very essential for reducing noise and getting a constant output power on varying loads. A good DC voltage regulator able of providing more than 2 Amps @ 40V can be used.You can expect such a power supply design very soon here in the power supply section.


Assemble the board on a good quality PCB.Use a preamplifier board with tone control prior to this amplifier to get better performance. If you don’t want no problem because this amplifier circuit has enough punch with in it.


R1………………2K2 1/4W Resistance
R2………………27K 1/4W Resistance
R3R4………….2K2 1/2W Trimmers
R5………………100R 1/4W Resistance
R6………………1K 1/4W Resistance
R7,R8……….. .330R 1/4W Resistance

C1 ………………22µF 25V Electrolytic Capacitance
C2 ………………47pF 63V Polyester or Ceramic Capacitance
C3,C4 …………100µF 50V Electrolytic Capacitance
C5 ………………2200µF 50V Electrolytic Capacitance

Q1 ………………BC550C
Q2 ………………IRF530 or MTP12N10
Q3……………… IRF9530 or MTP12P10

25 Watt Power Amplifier using TDA2009


Here is the circuit diagram of a 25 W power amplifier made of TDA 2009 IC.TDA 2009 has two channels each rating 12.5 watts on 4 Ohm load.Here the two channels are bridged to get a single out put channel weighting 25 W.

TDA 2009 IC has also built in features such as short circuit protection,thermal protection, overload protection etc using very low external components.The most interesting factor I see about this IC is that it require no dual supply.

Circuit Diagram of Amplifier and Power Supply


  • Do not connect more than 24 V to TDA 2009.
  • If 5 ampere bridge is not available make one using four 5 A diodes.
  • Fit a proper size heat sink to TDA 2009
  • Do not operate the circuit without heat sink.
  • For volume control connect a 10K pot
  • All capacitors in this circuit must be rated above 25 V.
  • Capacitors with + mark are electrolytic and that lead will be positive.Other capacitors will be normally ceramic.If there is exception that will be given there in the circuit or parts list.This law applies to all circuits in this site.

Tweeter Crossover circuit


A single coil speaker is not good in handling high and low frequency at the same time. If we could filter out the low frequency and play it through a tweeter ,it will produce more sound quality than using a single speaker.This is what is realized here.Here the high frequencies are filtered out using a low pass filter made of C1,C2 and R1 and send to the tweeter.The low frequency is only fed to the woofer.

Circuit Diagram with Parts List


  • The tweeter can be a 2 to 3 inch, 4 to 8 Ohm one .
  • R1 is used to adjust match the the tweeters output level to that of woofer.
  • C1 and C2 are electrolytic capacitors.
  • R1 should be rated more than 2 Watts.

Tuesday, March 18, 2008

Morse Code Beacon Keyer


This circuit stores a single morse code message as bits in an EPROM chip, the message is sent to a relay which can key a CW transmitter. The keyer can output either a one-shot message such as "CQ DX DE CALLSIGN", or a continuous message. The continuous mode is useful for making low power (QRP) beacons. A One-shot message is controlled by the start/stop buttons, a continuous message is sent by turning on the free run switch. EPROMs other than the 2732 can be used if suitable changes are made to the circuit. For larger EPROMs, just ground the higher order address input lines on the EPROM chip, and wire the appropriate chip select pins for outputs enabled and chip selected.

It is also possible to store more than one message in different banks of a larger EPROM, for instance, if a 2764 part were used, the A12 address line could be used to select the upper or lower message.


CMOS Nor gates U1c and U1d form a gated astable clock oscillator, the frequency can be adjusted by potentiometer VR1. Gates U1a and U1b form the run/stop flip-flop. In one-shot mode, this is activated by pressing the start switch, and deactivated either by pressing the stop switch, or by the end of message signal that comes from the EPROM d1 line.

The clock oscilator causes U2, a binary counter, to step through some of an 11 bit binary count. This sequence is used to step through the addresses on EPROM U3. Morse code data is stored in the EPROM d0 bit, it is used to turn on and off Q1 and RL1, the keying relay. At the end of a one-shot message, a single 1 bit arrives on U3 pin d1, causing the run/stop flip-flop to turn off, and resetting the U2 counter to zero. D1, C2 and R4 cause U2 to reset when the power is applied. R5 is used to prevent the U3 d1 line from being shorted to +5v when the stop switch is pressed.

Programming the EPROM

I have written a C language program called cw2hex that is used to convert a sequence of ASCII characters into a hex data image that can used for programming the EPROM chip that is used in this circuit. The program takes text input and produces an Intel Hex format file as output. The hex file should be readable by most modern EPROM programmers.

The C source code and Unix Makefile are in the file cw2hex.tar.gz (tar.gzip). A DOS executable version of the code is available as cw2hex.exe. It should be possible to compile cw2hex.c on any machine with a C compiler. The C program source files are available if you want to look at the code from your web browser.

cw2hex.tar.gz cw2hex source files for building under Unix/Linux (

C program cw2hex source files in text form for other platforms

cw2hex.exe DOS binary of cw2hex

Monday, March 17, 2008

Simple 40W inverter


This is the schematic of a simple 40W , 12 to 220 V inverter.You don’t believe, this is simple and cheap and working for me for last 4 years.The heart of the circuit is a CD 4047 IC which is wired as an astable multi vibrator here.Resistance and Capacitance at pin 1&2 determines the out put frequency.Here it is set to 60Hz.Due to this a two 180 degree out of phase ,120 Hz , 50% dutycycle waveforms will appear at pin 10 & 11.These waves are amplified by the complementary symmetry amplifier made of transistors BC 337 & TIP 3055 to drive the out put transformer.Don’t get feared of the technical terms, just wire it on a all purpose PCB.It is simple and will work.Don’t worry about the transformer windings ,buy a 220-110-0 primary,12-0-12 secondary , <50w>

Circuit Diagram:

Tips :

First wire to oscillator part only.Then check out put Pin 10 &11 of CD4047 to obtain the required wave forms ( two 120Hz ,180 degree out of phase,50% duty cycle waves.

Then connect transistors ,transformer and load (25 W bulb for test).See it working!.

Long Range FM Transmitter


The use of transmitters which have a more powerful output than the ‘flea-power’ are sometimes required when there are many obstacles in the path of the surveillance transmitter and monitoring station receiver, or the distance between them is too far so as to make a low powered devicefeasible. Whereas a typical microtransmitter will produce an RFpower in the order of just a few milliwatts, i.e. a few thousandths of awatt, the VHF-FM transmitter described has a poweroutput of between around a half and 2 watts, depending on the power source, which may be anywhere between 6 volts and 30 volts d.c. The battery or batteries should be of the alkaline high power type, sincethe current drain will be found to be relatively higher when comparedto microtransmitter current drain. The power output of this device is somewhat proportional to the current drain and so therefore both may be decreased by altering the value of R6 to a higher resistance, or a variable resistor with a value of around 1k may be introduced in series with the existing R6, so as to give a variable power output. Thevariable resistor must not be a wirewound device because this wouldact as an inductor which will cause feedback problems.

The audio input to the power oscillator, which incidentally is formed by TR2 and associated components, is derived from a piezoelectric microphone which drives the simple audio frequency amplifier TR1. The input of the audio amplifier is controlled by the gain pot R1, which selects the correct amount of voltage that is generated by the piezoelectric microphone, then connects this signal to the base of audio amplifier TR1 via C7. It may be found that there is insufficient housing space for a bulky piezoelectric microphone, so with a slight modification to the circuit, it is possible to employ an electret microphone insert as shown Since the RF field that is generated by this transmitter is relatively large, the problem of RF feedback may very well be encountered. This may be overcome by placing the transmitter inside a metal enclosure, keeping all internal wiring as short as possible and the aerial wire

Component listing for 1 watt transmitter

Resistors Semiconductors
R1 = 27k TR1 = BC547
R2 = 330k TR2 = 2N2219 fitted with heat sink
R3 = 5k6 MIC = piezoelectric microphone
R4, 5 = 10k
R6 = 100R

L = 6 turns 22 gauge enameled wire wound on 3⁄16″ former


C1, 2, 3, 8 = 330 pF
C4 = 2–10 pF trimmer
C5 = 4p7
C6 = 1 nF

Scream Generator Circuit


This is a real scream generator circuit suitable for any purpose like alarm or car horn.The circuit is based on two transistors Q1 and Q2.When you press the switch S2 the siren starts up moving to a high frequency.When the switch is released the tone slips down until you shift it up again by pushing the switch S2.

Circuit Diagram with Parts List.
Notes .

  • Adjustment of tone quality can be obtained by different values for C2.
  • If the alarm oscillates before S2 is pressed.The transistor is leaky, replace it.
  • S1 can be used as a power switch.

Wednesday, March 12, 2008

Multi Chip Programmer

This circuit is only a mirror dat from the actual web site


All the components fit on the single-sided board and the project is connected via a 4-pin US telephone plug to the serial port of a computer. It gets all its voltages from this port as well as the programming signals.
The diagram below shows the layout of the board. The three jumper links should be fitted first and then the diodes. Make sure you can identify the 4 signal diodes and the 5v1 and 8v2 zeners. The band or "line" on the diodes is the cathode end and this is shown by a line on the overlay. The only other components requiring careful fitting are the LEDs and transistors. Don't fit them too close or leave them too high off the board. A gap of about 3mm to 5mm looks the most professional. Solder them quickly to prevent heat running up the leads and damaging the semiconductor junction. The electrolytics are identified on the body of the component with a black stripe while the positive lead is identified on the board.

No ZIF (zero insertion force) socket is provided in the kit because they are very expensive and not necessary if you put the chip you are programming in an additional socket. This will make the PIC chip easy to fit and remove from any socket and keep costs down.
The cut-out on the end of the socket identifies pin 1 and the diagram below shows how to fit different types of 8-pin chips to the programmer. The last components are the resistors and socket and the board is ready. The next thing is the assembly of the serial cable.

The Multi-Chip Programmer is connected to a computer via a serial cable. The components to make this cable are included in the kit.
You have to be careful when soldering the 4 wires to the pins of the 9-pin D-plug to make sure they are soldered to the correct places. It's very easy to make a mistake. A 4-pin US plug (telephone plug) is supplied clamped to the cable and it clicks into the socket on the PC board. Attach it to the board and bare the free end to see how the 4-core cable has been connected. From this information, you should determine how the leads will be connected to the 9-pin plug. Select the appropriate diagram from the layout below and wire the conductors to the plug, including the 2k2 resistor. This should be done neatly as it has to fit inside the backshell. Screw the 9-pin D-plug together and you are ready to program a chip.

9 PIN D-SUB MALE at the Computer.








Carrier Detect




Receive Data




Transmit Data




Data Terminal Ready




System Ground




Data Set Ready




Request to Send




Clear to Send




Ring Indicator

Modification: Use 470R in the back-shell of the serial cable.

The circuit contains three indicator LEDs:
The 5v Power LED shows when 5v is present on the circuit.
The 13v Programming LED. At the commencement of the "burning" process, the chip will be put in "Programming Mode" by applying 13v to pin 4.
The Clock LED. During the "burning process" the "Clock LED" will illuminate to show data entering the chip.


(incl: all parts, PCB, cable, and postage)

2 - 470R 1/4 watt resistors
1 - 4k7 1/4 watt resistor
1 - 10k " "
1 - 10u 16v electrolytic
1 - 22u 16v electrolytic
1 - 3mm Red LED
1 - 3mm Green LED
1 - 3mm Yellow LED
4 - 1N 4148 signal diodes
1 - 5v1 zener 400mW
1 - 8v2 zener 400mW
2 - BC 547 transistors or similar
1 - 18pin IC socket
1 - 30cm fine tinned copper wire
1 - 30cm very fine solder
1 - 4-pin US telephone socket (low profile)
(RJ12 6P4C PCB socket)
1 - Multi-Chip Programmer PC board

Serial Cable:
1 - 2k2 resistor or 470R
1 - 4-pin US plug on 6ft 4-core cable
( RJ12 6P4C crimp plug)
1 - 9 pin D-type socket
1 - 9 pin backshell

Thursday, March 6, 2008

How to build your own PIC-Programmer

The original schematic was developed by Radu Igret. It is a modification of a JDM-Programmer. This PIC-programmer has to be connected with the serial com port of your computer. This device don’t need any external power supply. The print layout was made with Eagle by CadSoft.

Which types of PIC microcontrollers and EPROM’s are supported?

You can use this PIC-Burner for PIC12C50x, PIC12F62x, PIC16FFxx, PIC16F62x and EEPROM 24Cxx. This PIC-Programmer was tested with PIC12C508 (A), PIC12C509 (A), PIC12F629, PIC12F675, PIC16F84A, PIC16F627, and PIC16F628.

The PIC-programmer is easy to build and compact. 3 LEDs indicates the state of the burning-process. Red: burning, yellow: clock-signal, green: power supply. The dimensions are about 50 mm x 62 mm.

The Modification of this JDM-Programmer:

In comparison to the original JDM-Programmer exists a connection between pin 10 (JDM) and Vss instead of VDD. This modification makes it possible to program PIC microcontrollers with LVP-function (for example PIC16F627 or PIC16F628).

The Schematic of the PIC-Programmer:

The wiring diagram was drawn with Eagle-Lite by CadSoft in order to create a print layout by my self. Eagle is very popular print layout software in Germany and for non-commercial use free.

The schematic view of the PIC-Programmer ( The bipolar npn-transistors are not very critical. Probably you can choose almost any small signal types. The capacitors are 16 Volts types. The SUB-D-connector is female and has 9 Pins (Reichelt-Best.-Nr.: EMV-BUCHSE 09W). All resistors are common and have 1/4 Watts, 5% tolerance (Download of the Eagle-SCH-file for the schematic here).

The Print Layout:
I developed the print layout with the help of Eagle. Because I am not a professional lay outer I used the auto router. After some tries and errors I came to a practical solution for homebrewed stuff. My intention was not to build something for the industrial mass production.

The component side of the pic-programmer. The small holes have a diameter of 0,8 mm, the 6 big ones 3,5 mm. It is recommended to make the print of the layout with Eagle and the Eagle-BRD-file (Download here the jdm-layout.brd and the folienausdruck.brd, which is prepared for the print).

Feel free to modify and improve my Eagle files provided you don´t use them for commercial purposes. By the way here is the print-layout as a picture (layout-as-picture.gif). ( quality is not as good as a print with the Eagle-file. Don´t forget to resize the dimensions of this picture.Otherwise the components will not fit. I recommend the picture-viewer-software IrfanView.

How to insert the PICs and EEPROMs:

The Software IC-Prog:

At least you need a software on your PC in order to copy the hex-codes on your hard disk into the PIC. By the way there are hundreds of hex-codes for PICs in the Internet. You don´t need to be a PIC-programmer. Just download and burn.

I use this pic-programmer in combination with the free windows-software IC-Prog. ( This software supports also this modified JDM-Programmer.

IC-Prog: Choose this configuration for the JDM-Programmer.

My personal Experience:

The burning, flashing, erasing and testing of used and new PICs takes 20 to 50 seconds. However I did not succeed in flashing a used PIC, which was programmed by an other PIC-Programmer. I don´t know the reason.

Download: This zip-file contains the entire web-page ( including all files and Eagle-files.

Wednesday, March 5, 2008

Multi PIC Programmer By FENG3

Reference: Article present in HAM RADIO INDIA website

Multi PIC Programmer 5 Ver.2 is a PIC programmer, which can program to 8-pin to" 40-pin devices using single ZIF socket.

It is the first PIC programmer, which was built by me when I began electronics hobby one year ago. There are many kinds of PIC programmers. The programmer, which I built, does not need an external power supply, and since there are only few parts, it is very cheap and can be built easily. This PIC programmer is called "JDM programmer". This name comes from the name of Jens Dyekjar Madsen who devised this first. His homepage is here.

I built "Multi PIC programmer 5 Ver.1", in order to enable it to program 40-pin devices like PIC16F877 with a ZIF socket. The number "5" is because it is the 5th set of the programmers which I built based on the JDM programmer. This PIC programmer's circuit diagram can be downloaded from my homepage.

Lately I improved this PIC programmer. The main improvements are having made it suit "VPP before VDD" and changed wiring of a ZIF socket for accepting devices with LVP (Low Voltage Programming) mode. Information about "VPP before VDD" is available in my homepage.

Before you build this "PIC programmer", I recommend checking to see if there is enough output voltage at the serial port your personal computer. If TxD, DTR, and RTS do not have more than +7.5V(or -7.5V), this programmer will not work well, especially, with the latest laptop computers that using low power RS232 interface ICs.

Other important matters are as:

  1. The GND line of a serial port forms relative VDD on a PIC programmer. All the GND symbols in a circuit diagram are a PIC programmer's GND. Never connect them with GND line of a serial port
  2. This PIC programmer changes VPP in accordance with the device selected (8-18pin) or (28-40pin) with one sliding switch. So, if the insertion position of a device and slide switch is not set correctly, your PIC may be damaged by over voltage.
  3. This PIC programmer does not support all PIC MCUs. (PIC16C5x is not programmable with this programmer By using an adapter, the 20 pin PIC 16C770/771 can be programmed.
  4. I did not try all PICs since and I do not have all them. The PICs, which I successfully programmed and verified, are PIC12F629, PIC12F675, PIC16F627, PIC16F628, PIC16F630, PIC16F676, PIC16F818, PIC16F819, PIC16F84A, PIC16F873, PIC16F877A, PIC18F2320, PIC18F452.
  5. The programming software used is IC-Prog( of Bonny Gijzen. Go to the following link to download the software.
  6. (

  1. Hardware settings" of IC-Prog are the same as the JDM programmer.

I am publishing this circuit diagram and the PCB for the first times for the benefit my friends in of India.

Download PDF files (PCB designs).

Since the question about which I am often asked had many things about PCB and P channel MOS-FET, I drew the following PCB and others. PCB size is 100 mm x 37.5 mm. The spacing of first pin and No.20 pin of ZIF Socket is 48.26mm. If a PDF file prints smaller or larger than expected (for example, 90% of the original size) from an Adobe Acrobat product, do one or more of the following:

Print using different paper source options.
Choose File > Print, and then do one of the following:

  • In an Acrobat 6.x product, select Choose Paper Source by PDF Page Size, and then click OK.
  • In an Acrobat 5.x product:
    1. Click Advanced.
    2. Select Choose Output Tray by PDF Page Size.
    3. Click OK to close the Print Settings dialog box, and then click OK to print.

Modifications on Multi PIC Programmer 5v2

One problem of Multi PIC Programmer 5V2 is that it is difficult to find a 2SJ377 and its substitutes. 2SJ377 can be bought from RS Components. IRFR9024(D-PAK) can be bought from Digi-key. About BSP254A, it is uncertain whether it works well even if it is found.

Therefore, I improved Multi PIC Programmer 5V2 only a little at the end of last year. It is a circuit that can use a general purpose PNP transistor instead of a P-channel MOSFET.

SW2 is a board mount Post Header(3 or 2 posts, single row male) and a Post Shunt(Shorting Jumper).

This Multi PIC Programmer works as a usual JDM Programmer. When the switch-2 is on, this Multi PIC Programmer changes into VPP-FIRST mode

The switch-2 will be used only when both INTOSC and internal MCLR options are selected (PIC12Cxxx,PIC12CExxx,PIC12F629, and PIC12F675,etc. Please refer to the data sheet of each PICs for more details.)

I built it by using components that would be able to be bought even in your country. Though I have tested a few devices, it works well for now.

In the schematics and PCB layouts, there are somethings with a different connection of R5. Please disregard it because it must be not unrelated to function of hardware.

Download the Circuits and PCB layouts for the modified version (

Your questions and comments on this project may be put to the Forums on this web.