8/17/2019 9e0f1003-ddcb-4eee-98f1-f69098a6f89e-150611180832-lva1-app6892

1/5

8/17/2019 9e0f1003-ddcb-4eee-98f1-f69098a6f89e-150611180832-lva1-app6892

2/5

ET 2530 FM Transmitter project

FM Transmitter %perations

T$e FM Transmitter is a FM mo&"lation Transmitter 'itc$ mo&"lates an intelligence

signal an& a carrier (re)"ency* T$e mo&"lation ta+es place in t$e MAX2606 c$ip* T$e t"ning is

accomplis$e& t$ro"g$ t$e (ilter circ"itry an& t$e "se o( t$e #00,000 o$m pot* T$e -ol"me is

controlle& .y t$e #0,000 o$m pot* T$e t"ning circ"itry is connecte& to pin 3 o( t$e MAX2606

c$ip* T$e -ol"me is also connecte& to pin 3* T$e o"tp"t is ta+en (rom pin 6 an& sent to an

antenna* /egati-e (ee&.ac+ is s"pplie& to pin (rom t$e o"tp"t* Pin 5 is set (or 1cc at 51

t$ro"g$ t$e "se o( a -oltage reg"lator* T$e inp"t signal is s"pplie& t$ro"g$ t$e "se o( 2 !A

 jac+s*

From my eperience t$e project 'as a s"ccess, I $a& no &i((ic"lties p"tting t$e circ"it

toget$er* I enjoye& sol&ering t$e components to t$e .oar&4 t$is ga-e me m"c$ nee&e& practice* I

 .elie-e t$e so"n& 'as a&e)"ate (or t$e po'er le-el o( t$e transmitter* T$e only t$ing is '$en t$e

-ol"me o( t$e transmitter 'as too lo"& I got a little &istortion*

T$eory o( operation

2

8/17/2019 9e0f1003-ddcb-4eee-98f1-f69098a6f89e-150611180832-lva1-app6892

3/5

ET 2530 FM Transmitter project

T$e FM transmitter 'or+s as (ollo's (irst po'er is s"pplie& t$ro"g$ t$e -oltage reg"lator 

t$at steps &o'n t$e -oltage to 5 -olts* econ& pin 5 is s"pplie& 5 -olts (rom t$e -oltage reg"lator*

Pin 6 is t$e o"tp"t (rom t$e MAX2606 'itc$ is s"pplie& t$ro"g$ a capacitor to remo-e any !

element in t$e signal, an& t$en t$e signal is sent to an antenna* Pin 6 t$ro"g$ a -oltage &i-i&er

t$e t'o #,000 o$m resistors sen&s negati-e (ee&.ac+ to pin (or (re)"ency sta.ility* Fi-e -olts is

sent to t$e #00,000 o$m* Pot t set a &i((erential .et'een gro"n& an& 1cc in t$e pot* T"ning is

accomplis$e& at pin 3 t$ro"g$ t$e "se o( a 2 pole lo' pass (ilter t$e #00,000 o$m pot accomplis$

t$at jo. .y c$anging t$e ! circ"it -al"e* 1ol"me is controlle& .y t$e #0,000 o$m pot .y

limiting t$e c"rrent s"pplie& .y t$e !A jac+s* T$e in&"ctance is "se& .y t$e c$ip to create a

7! circ"it 'it$ in (act is part o( t$e t"ning circ"it* T$e MAX2606 also ampli(ies t$e signal (or

transmission t$ro"g$ t$e antenna*

7ist o( parts

3

8/17/2019 9e0f1003-ddcb-4eee-98f1-f69098a6f89e-150611180832-lva1-app6892

4/5

ET 2530 FM Transmitter project

  8905 1oltage reg"lator I!

FM transmitter sc$ematic

4

8/17/2019 9e0f1003-ddcb-4eee-98f1-f69098a6f89e-150611180832-lva1-app6892

5/5

ET 2530 FM Transmitter project

5