cordless mike

[RAMAN KAPOOR]

can any body help me in making cordless mike

 

[audioguru]

1MHz AM?
100MHz FM?
How much RF power?

 

[RAMAN KAPOOR]

1MHz AM?
100MHz FM?
How much RF power?

i need it of 100mhz fm sir.

 

[i_build_stuff]

.s

 

[audioguru]

My FM transmitter works much better than all the toy transmitters on the web:

 

[RAMAN KAPOOR]

My FM transmitter works much better than all the toy transmitters on the web:

sir i have recived the circut many thanks for that but con you explin the circut because i am new to electronics.

 

[audioguru]

You must learn about electronics or you won't understand what I say about the circuit. When you know electronics then the circuit will be obvious.

 

[moody07747]

not busting your chops here but just for the record its spelled mic

 

[RAMAN KAPOOR]

You must learn about electronics or you won't understand what I say about the circuit. When you know electronics then the circuit will be obvious.

sir i am not too new to this line. i am little bit able to understand the circut but not completly or rather give me the components list relevant to your circut . which are not clear in you circut . thanku i shall be obliged

 

[audioguru]

give me the components list relevant to your circut . which are not clear in you circut

Sorry, I don't have a parts list. The schematic looks clear. Which parts aren't clear to you?

Q1 is a microphone preamp with pre-emphasis. Q2 is an RF oscillator with AM and FM modulation from the preamp. Q3 is an RF amplifier that isolates the antenna from the oscillator. The LM2931 is a low-dropout 5V regulator that still works fine when the 9V battery drops to 6V over its life.
Capacitors marked pF are ceramic disc, nF are metalized plastic film, uF are electrolytic. The coils are easy to make.

Its range is more than 2km line-of-sight to a pretty good FM radio.
Is there anything more you need to know?

 

[TronicBrain]

Nice schematic audioguru

and I have a quistion

can I replace LM2931 with 7805?

and What is the function of c6 & c13 ?

thanks

 

[audioguru]

Nice schematic audioguru

Thanks.

can I replace LM2931 with 7805?

A 7805 needs a minimum input voltage of about 7.5V. A 9V alkaline battery's voltage drops quickly to about 7.2V then a 7805 might not work. I chose the LM2931 becauase it is a low-dropout regulator that works fine with an input voltage of only about 5.5V when the 9V battery is dead.

What is the function of c6 & c13 ?

C6 tunes the transmitter's RF frequency. C13 peaks the max power at the frequency of the oscillator but its peak is very broad.