Circuit analysis

Thread Starter

N0t_S0_Sm4rt

Joined Apr 6, 2019
13
Hello,

please, would some good person help me with analysis of this circuit (my guess it's a FM radio). My task is to revive it, however I don't quite know how.
circuit.jpg
What I'd do:
1. Connect the circuit to 9 V voltage source
2. Divide the circuit to 2 parts - AC and DC
3. Search for voltage dividers in DC part

I don't possess much knowledge about transistors. What would you do to make this circuit alive and check whether everything works. How would you calculate certain important values.

THANK YOU, any help or advice is highly APPRECIATED!!!!
Have a nice day!
RN
 

dl324

Joined Mar 30, 2015
11,845
What I'd do:
1. Connect the circuit to 9 V voltage source
2. Divide the circuit to 2 parts - AC and DC
3. Search for voltage dividers in DC part
You're on the right track. Since the stages are AC coupled, it's straightforward to determine the correct bias voltages.

The input looks like a microphone to me.
 

Thread Starter

N0t_S0_Sm4rt

Joined Apr 6, 2019
13
It is not an FM radio, in other words, it is not a receiver.
It is a microphone FM transmitter.

Is this homework?
Thank you! It's not a homework :D but we're likely to get it on an exam...

You're on the right track. Since the stages are AC coupled, it's straightforward to determine the correct bias voltages.

The input looks like a microphone to me.
Thank you!
 

WBahn

Joined Mar 31, 2012
26,273
What does it mean to "revive" a schematic and why are you trying to revive a schematic for something when you don't even know what the something is? o_O
 

Thread Starter

N0t_S0_Sm4rt

Joined Apr 6, 2019
13
What does it mean to "revive" a schematic and why are you trying to revive a schematic for something when you don't even know what the something is?
Revive - to make it working. I'm asking for a procedure - theoretically, if you'd see this circuit, what would you do... I'm well aware that I perhaps want too much... It's just the way it works on our school, you're given a circuit without explanation what it is...
 

MrChips

Joined Oct 2, 2009
22,068
This is a practice question that you could be asked in an exam. That makes it homework.
Since this is course related material, you ought to have covered most of it in class.
Hence, tell us everything you know from looking at the circuit. You cannot expect us to be there by your side in an exam or job interview.
 

jtn

Joined Mar 27, 2017
22
Try to build this circuit using Spice program such as Simetrix Spice. You should be able to decode and understand circuit once you see the analysis results in Spice. Study BJT amplifier circuit, Ohm law...
 

MrAl

Joined Jun 17, 2014
7,849
Hello,

please, would some good person help me with analysis of this circuit (my guess it's a FM radio). My task is to revive it, however I don't quite know how.
View attachment 219504
What I'd do:
1. Connect the circuit to 9 V voltage source
2. Divide the circuit to 2 parts - AC and DC
3. Search for voltage dividers in DC part

I don't possess much knowledge about transistors. What would you do to make this circuit alive and check whether everything works. How would you calculate certain important values.

THANK YOU, any help or advice is highly APPRECIATED!!!!
Have a nice day!
RN
Just a quick tip.

If you really want to understand this circuit and dont have much experience with transistors you should probably start with a simpler circuit and work your way to this circuit. Start with say an audio amplifier, they are much much simpler to understand and get a rough idea how transistors work in circuits in general.
 
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