OK2PEN's home made electronics     (c)OK2PEN
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Inteligent NiMH/NiCd charger
70cm UHF Mini yagi


GPS antena for GARMIN RCVR
Audio amplifier with TDA2009A


Car hermetic battery charger
Programmer for Microchip's PICs


Tinytrak3 - GPS position tracker
Mini FM transmiter


Compact FM_PLL transmiter






INTELIGENT NiMH/NiCd CHARGER

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Below there is one description of my NiMH/NiCd battery charger which is comparable with the expensive charger from fa ANSMAN GmbH but costs just about a quarter of their market price. The charger uses U2402B chip from fa TEMIC. The chip is described on the WEB and has more modified equivalents like U2405B and U2407B. Each of them are practically same only with small differences. One of quite good sources to look for are on ASICentrum pages http://www.asicentrum.cz and my version was developed on basis of these pages.


SCHEMATIC
BOARD TOP
BOARD BOTTOM
DEVELOPMENT
PROTOTYPE
FINAL PRODUCT




SCHEMATIC DIAGRAM

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CIRCUIT BOARD - TOP SIDE

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CIRCUIT BOARD - BOTTOM SIDE

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DEVELOPMENT AND TESTINGS

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PROTOTYPE

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FINAL PRODUCT (6 fotos below)

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Printed circut board "hand drawn" :)


Charger part view


Discharger part view


View of all circuit


Case top view


View inside the case from bottom


70cm UHF Mini Yagi antenna

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Below there is one description of my mini yagi UHF 430-440 MHz Yagi antenna. The center frequency is 434 MHz. The antenna is used for packet radio on that band and has the gain of about 13 dB. The antenna is pretty directional (horizontal angle +/- 10 degrees) and with good polarization surpression. If you will built it, please make exact dimmensions as shown on the drawing. The decimals of mm can be omitted.


DRAWING
DRIVEN ELEMENT
BALUN
FEEDING DETAIL 1
FEEDING DETAIL 2
OVERALL VIEW




ANTENNA DRAWING

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DRIVEN ELEMENT

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View of driven element with matching wires

SYMETRIZATION BALUN

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Symetrization balun from a piece of RG-58 full shield coax cable

FEED DETAIL 1

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Driven element feeding assembly in detail 1

FEED DETAIL 2

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Driven element feeding assembly in detail 2

OVERALL VIEW

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Overall view of the antenna. It's only 55 cm long.

GPS external antena and coupling to the GARMIN GPS receiver

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Below fotos of GPS turn-style miniantena and its coupling to GARMIN GPS receiver which has no any connector for external antenna. Also shown DB-9 adaper to output GPS pins. The pins are +3V RXD TXD and GROUND. Placing the antenna under the front window of the car I receive minimum 7-9 satellites in one moment depending on surrounding country side.


DB-9 Adapter - top
DB-9 Adapter - bottom
Antenna coupler
Antenna coupler with GPS
GPS antenna - pic 1
GPS antenna - pic 2
GPS antenna - pic 3
GPS antenna - pic 4







Connector adapter - top view

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Connector adapter - bottom view

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Antenna coupler with BNC connetor

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Antenna coupler mounted

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Driven element feeding assembly in detail 1

Antenna detail - coax connection

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Antenna detail - elements

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Antenna view from side

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Antenna overall view

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Audio amplifier with TDA2009A

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Below here is the description of my stereo audio amplifier using the chip TDA2009A. This amplifier must have both speakers connected otherwise it is drawing high current more then 1 A. Although the chip has the temperature protection inside it is not recommended to switch the circuit without both speakers connected. With the input signal the supply current at 12 Volts can reach upto 5 Ampers so good 12V/5 Amper power supply is needed. It can be supplied from the switched AT pc supply as well. That's why also good radiator to be mounted to the amp case (not shown on photos).


SCHEMATIC
VIEW 1
VIEW 2
VIEW 3




SCHEMATIC DIAGRAM

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View 1

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View 1

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View 1

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CAR HERMETIC BATTERY CHARGER

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Below is the description and photos of the automatic car hermetic battery charger. The charger is charging in mode of constant current of about 1 Amper. There is LM350 voltage regulator working as constant current supply. The charging process is fully automatic. When the charge voltage reaches about 13.8 Volts the charging process is changed into trickle mode and keeps the battery loaded with a periodical current impulses. The charger is here built with the simple digital panel meter showing charge voltage or current.


Schema of charger
PCB of charger
Development
PCB bottom
View from top
View from bottom
Front panel mounting
Common view
Schema of meter
PCB of meter







Schema of the charger

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PCB of charger

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Development

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PCB bottom

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View from top

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View from bottom

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Front panel mounting (rear side)

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Overall view

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Schema of panel meter

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PCB of panel meter

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"JDM" Programmer for Microchip's PICs

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Below here is the description of a simple Microchip PIC "JDM" programmer. This programmer cooperates with the soft in Windows. The programmer is connected to COM port of the pc. Programmer can burn or erase most of types of the Microchip PICs. The software "pp4u_082_en.zip" you can download in the section Downloads. Case you will have problems with the installation of the soft please see webpage http://feng3.cool.ne.jp/en/rcd.html
The programmer works also with Linux soft "picprog-1.8.3.tar.gz" which you can also download from section Downloads but the author gives no function garantee.
The circuit board is 37x49 mm.


SCHEMATIC
BOARD
TOP VIEW
BOTTOM VIEW




SCHEMATIC DIAGRAM

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CIRCUIT BOARD

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TOP VIEW

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BOTTOM VIEW

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"TINYTRAK3 position tracker"

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Below is one of known constructions of the Tinytrak3 which is simple geografical position tracker enabling transfer of GPS data to be transmited by amateur radio into APRS net via APRS Digis. The Tinytrack is supplied by car voltage and switched between the GPS and any type of ham radio. This construction can be made more small as this one was made for test purposes. The radio on the Test picture is not connected.
The Tinytrak program for setting callsign etc. you can download in the section Downloads as well as the firmware for the PIC16F84-04/P. During programming the PC is connected via Null modem to the GPS connector.
Tinytrack3 has here PIC16F84A-04/P with 10 MHz crystal and old Tinytrak (not Tinytrak3) firmware. When Tinytrak3 firmware is available (the author has not released it and sells only the programmed PIC) PIC16F628A or PIC16F628-10 should be used and also setting program is different.
The circuit board is 71x49 mm.


SCHEMATIC
BOARD
TOP VIEW
BOTTOM VIEW
TEST PICTURE




SCHEMATIC DIAGRAM

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CIRCUIT BOARD

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TOP VIEW

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BOTTOM VIEW

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TESTS

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"Mini FM transmiter"

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Below is a small simple FM transmiter for a ship or home use to transmit for example some news from HF radio to ship's FM receivers in the high seas. Its range is about 100 meters.
The circuit board is 55x55 mm. R84 is 47 oHm.


SCHEMATIC
BOARD
BOTTOM VIEW
TOP VIEW
BOX VIEW




SCHEMATIC DIAGRAM

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CIRCUIT BOARD

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BOTTOM VIEW

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TOP VIEW

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BOX VIEW

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"Compact FM transmiter with PLL tuning"

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Below is a FM transmiter with PLL tuning for a ship or home use to transmit for example some news from HF radio to ship's FM receivers in the high seas. Its range is about 1 km with GP antenna. Firmware for PIC16F84 in asm and hex format you can download as pll_soft.zip in the section Downloads.
The circuit boards are joined into one board - see picture.


SCHEMATIC_TX
BOARD_TX
SCHEMATIC_PLL
BOARD_PLL
SCHEMATIC_MOD
BOARD_MOD

TX PART VIEW
PLL PART VIEW
MODULATOR PART VIEW
COMPLET VIEW




TX SCHEMATIC DIAGRAM

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TX BOARD DIAGRAM

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PLL SCHEMATIC DIAGRAM

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PLL BOARD DIAGRAM

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MODULATOR SCHEMATIC DIAGRAM

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MODULATOR BOARD DIAGRAM

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TX PART VIEW

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PLL PART VIEW

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MODULATOR PART VIEW

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COMPLET VIEW

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Best 73 de Libor OK2PEN

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