can anyone tell me hoe to do a technical paper.......
what s expected from engineering students,...
and what brings the winning strategy...
All semiconductor manufacturers make many low dropout 5V regulators. The 78L05 will stop regulating when the battery voltage drops to about 7V which will happen soon.Hi all,
I have built the FMTx Mod4..
and after finishing it I encountered a couple of issues..
1. as I could not get the low dropout V regulator I used an LM78L05.. That gets heated in less than 50 secs and shuts down.
Since the 78L05 got hot but the LM317 did not then maybe the pins on the 78L05 were connected backwards.So now I am replacing the V regulator with a regular LM317T circuit (set for 5V). Hopefully that will cure the heating issue. (done while wrting this email..) working perfectly
I don't know what is a peaking circuit. I made a "field strength meter" with an antenna and a detector diode for tuning my output.2. I constructed a simple peaking circuit and attached it to the antenna output .. I am not getting an reading on the DVM from the circuit.
Wrong. The base to emitter voltage of a 2n3904 transistor is about 0.7V, not 3.6V. Maybe its pins are connected backwards.Here are differnt voltage readings that I have taken along the way..
Supply regulated and filtered 9.60V
Q3-Vc = 9.60V
Q3-Vb = 3.6V
Q3-Ve = 8.1mV
Wrong. It is saturated. I don't think it is oscillating.Q2-Vc = 5.05V
Q2-Vb = 4.19V
Q2-Ve = 4.17V
Wrong. The collector voltage should be about 2.0V. The emitter voltage should be about 0.044V and the base voltage should be about 0.61V.Q1-Vc = .860V
Q1-Vb = .211V
Q1-Ve = .209
That is fine.Mic+ = 2.03V
Too many voltages are wrong in your circuit so it does not work.How do I tune the circuit .. what sequence would I apply. The circuit is made on a pcb to spec with no component alternates at all...
You should not connect your Field-Strength-Meter to the circuit because its capacitance changes the tuned frequency. Have the FSM at least 1m away from the circuit and have the circuit at least 2cm away from anything. The circuit can be spaced inside a metal box and then connect the box to 0V.1. Can the tuning process be made any simpler? For now I connected my FSM to each output of the stage and tuned it for max.
I think Q3 would get too hot.2. What would be the affect on the circuit if the 9V rail was upped to 12V leaving 5V rail as is?
I think it would just make interference on many frequencies (its harmonics).An another stage identical to the Q3 stage was added to the circuit after Q3?
I didn't measure the signal level. It is pretty low for an FM radio to produce the same output as an FM radio station playing loudly.3. last but not least. as I forget to write it down, what voltage should I be feeding to C3 for the optimal performance of Q2 stage.
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