|Flipped reverse side photo to match component side|
|MINI FM RADIO STATION Note top side component placement. Top two holes are for the 9-volt battery clip leads with ground on the left side. The left bottom hole and the bottom right hole are for the antenna connection.|
|Connections are easily seen when the printed circuit board is back lit, showing the circuit board traces on the reverse side. This makes it easier to match component locations to the schematic diagram.|
IN-HOUSE DIY RADIO STATION PART 2
|Rotated left to right view for component placement|
Work is progressing on the electronic construction of the Lab's two stage exampling FM radio station. Stay tuned to this series of blogs as we supply the details of going on the air, as well as technical info so you can roll your own in-house radio station for fun.
The test transmitter printed circuit board has 17 components mounted and ready for soldering. This blog details the component placement and the circuit traces on the printed circuit board and includes transistor placement guides and a schematic for assembly. Note the two transistor identifications in the illustration showing keyed emitter, base and collector locations.
|Verified leg identification ok|
Note that some countries and municipalities allow short range transmitters of this type and some do not. Be sure to first check local laws and regulations before proceeding with the project.
|The copper printed circuit side of the board with through hole leads ready for hot soldering|
|Ok to Use: MICRO Data/Japan data|
Frequency trimming is accomplished by stretching or compressing the coil or modifying the value of the ceramic parallel 10 pF capacitor.
Initially the frequency should be in the range of 88 to 108 mHz on the FM band.
|Warning - do NOT use USHA India/LGE leg positions|
The cost of the first set of parts is NT$132 (US$4.42) and the backup duplicate parts are NT$120 (US$4.00). Thus far, combined cost is US$8.42 for the hardware.
The transistor leg identification does not agree from one data sheet to the next. See diagrams.
Careful with data sheets for the 2sc1675 transistor as there are discrepancies between the TO92 and TO92b case versions. For example, the equivalent Panasonic 2sc 829 equal to 2sc 1675 as a substitute is in agreement with the transistor placement of emitter, collector, base, therefore this is the arrangement to use.
FM Radio Station Part 5 Index